CN113376309B - Method for determining starting scheme of hydrogen peroxide rocket engine catalytic bed - Google Patents

Abstract

The invention provides a method for determining a starting plan for a catalytic bed of a hydrogen peroxide rocket engine, which includes performing a bubble test, designing a starting sequence, conducting a catalytic test, correcting the starting sequence and obtaining a starting plan. Use the bubble sheet test to simulate the decomposition of hydrogen peroxide in the rocket engine, design the valve start sequence according to the result of the bubble sheet test, conduct the catalytic test in the rocket engine according to the start sequence, and then correct the next group of catalytic tests according to the results of the catalytic test. The start-up sequence corresponding to the test will gradually improve the start-up sequence. Finally, the last startup sequence is revised again and used as the startup scheme. The above process can specifically design a start-up scheme that completely matches the catalytic bed of the rocket engine, improve the start-up speed of the catalytic bed, and avoid excessive ignition pressure peaks in the combustion chamber during the ignition stage, thereby eliminating the risk of deflagration.

Description

Determination method of catalyst bed start-up plan for hydrogen peroxide rocket engine

technical field

The invention relates to the field of rocket engines, in particular to a method for determining a starting plan for a catalytic bed of a hydrogen peroxide rocket engine.

Background technique

As a propellant, hydrogen peroxide has excellent characteristics such as green and non-toxic, so it is widely used in rocket engines, and its main function is to act as an oxidant. At present, a series of studies have been made on the ignition scheme of rocket engines using hydrogen peroxide as propellant, and catalytic ignition has also been widely adopted as a kind of ignition scheme and has been widely used.

Compared with other schemes, the catalytic ignition scheme uses a catalytic bed, and liquid hydrogen peroxide is rapidly decomposed into water and oxygen when flowing through the catalytic bed, and is added to the combustion chamber in the form of a gas phase at the outlet of the catalytic bed, compared to Liquid direct injection is more conducive to ignition start and full combustion.

At present, for the catalytic ignition scheme, there have been many studies on the hydrogen peroxide catalytic bed, the main purpose of which is to improve the performance of the catalytic bed, improve the catalytic efficiency, and thus improve the performance of the engine. However, the research on the start-up scheme of the catalytic bed has hardly been carried out, such as the time interval for supplying hydrogen peroxide to the catalytic bed, the amount of hydrogen peroxide supplied each time, and the like.

On the one hand, the start-up speed of the catalyst bed is an important index to measure the performance of the catalyst bed, and the size of the start-up speed depends on the perfection of the start-up scheme. On the other hand, if the hydrogen peroxide catalytic bed does not adopt a reasonable start-up plan, a large amount of uncatalyzed liquid hydrogen peroxide will exist in the outlet product of the catalytic bed, causing the ignition pressure peak in the combustion chamber in the ignition stage, and the danger of deflagration .

Different catalyst beds are suitable for different start-up schemes, and the existing catalyst beds cannot be designed to completely match the start-up scheme in the working process.

SUMMARY OF THE INVENTION

In order to solve the problem in the prior art that a startup scheme that completely matches the catalytic bed cannot be designed in a targeted manner, the purpose of the present invention is to provide a method for determining the startup scheme of the catalytic bed of a hydrogen peroxide rocket engine.

The present invention provides the following technical solutions:

A method for determining a starting plan for a catalytic bed of a hydrogen peroxide rocket engine, applied to a rocket engine, the rocket engine includes a catalytic bed assembly, the catalytic bed assembly includes a casing and a catalytic bed body made of silver mesh, the The inlet end of the casing is connected with a head cavity, the outlet end of the casing is connected with a combustion chamber, the catalytic bed body is located in the casing, and the inlet end of the head cavity is connected with a supply system through a valve;

The determination method of the hydrogen peroxide rocket engine catalytic bed startup scheme includes:

Carry out multiple groups of blister tests on the silver net;

Design a first start-up sequence for the valve according to the results of the first group of the blister tests, the start-up sequence includes an opening duration, a closing duration and a number of closings, and the opening duration and the closing duration are alternately set;

According to the first described starting sequence, the valve is controlled to be opened within the time period corresponding to the opening duration, and closed within the time period corresponding to the closing duration, so as to supply hydrogen peroxide into the housing for the first step. A set of catalytic tests, and observe the flow and accumulation of the product at the outlet end of the casing inside the combustion chamber;

By analogy, according to the results of the n+1 group of the bubble sheet test, the n+1th start sequence is designed for the valve, and the nth group is revised according to the flow and accumulation in the nth group of the catalytic test. n+1 said start-up sequences, and perform the n+1th group of said catalytic tests according to the n+1th start-up sequence, where n is a positive integer; and

According to the flow and accumulation conditions in the last group of the catalytic tests, the last start-up sequence is revised again, and the revised last start-up sequence is used as the start-up scheme.

As a further optional solution to the determination method of the hydrogen peroxide rocket engine catalytic bed start-up plan, the described silver net is subjected to multiple groups of blister tests, including:

Sampling the silver mesh from the same production batch as the catalytic bed body, and cutting the silver mesh into slices with the same size and quality;

Set up multiple groups of beakers, inject hydrogen peroxide into the beakers, and the concentration of the hydrogen peroxide injected into the beakers is the same as the concentration of hydrogen peroxide used by the rocket motor;

Put the slices into the first group of the beakers and start timing. When the hydrogen peroxide in the beaker is completely decomposed, the timing is ended. During the timing process, the overall quality information of the beaker is collected by the sensor, and the mass change is obtained. curve;

By analogy, put the slices after catalysis in the beakers of the mth group into the beakers of the m+1th group, where m is a positive integer, repeat the process of timing and collecting quality information, and obtain the corresponding the mass change curve; and

A first critical value is set, and the blister test ends when the difference between the time lengths required for complete decomposition of the hydrogen peroxide in the adjacent two groups of the beakers is less than or equal to the first critical value.

As a further optional solution to the method for determining the start-up plan of the catalytic bed of the hydrogen peroxide rocket engine, the n-th start-up sequence is designed for the valve according to the result of the n-th group of the blister tests, n is a positive integer, including:

则所述开启时长为

Denote the volume flow of the valve as Q _v , denote the volume of the catalytic bed body as V _t1 , denote the volume of the head cavity as V _s , according to the porosity parameter of the silver mesh provided by the manufacturer

Then the opening time is

根据所述质量变化曲线，计算出自开启计时起所述烧杯的整体质量每减少Δm所需的时间作为多个t₂，最终得到多个所述关闭时长t₃＝t₂-t₁；和Denote the mass of the slice as m ₁ , denote the mass of the catalytic bed body as m _c , and denote the density of hydrogen peroxide as ρ, then the time t ₂ required for the complete decomposition of hydrogen peroxide in the rocket engine is equal to the the time required for the overall mass of the beaker to decrease by Δm, and

According to the mass change curve, the time required for each decrease of Δm in the overall mass of the beaker since the time of opening is calculated as a plurality of t ₂ , and finally a plurality of the closing time lengths t ₃ =t ₂ −t ₁ are obtained; and

A second critical value is set, and only the shutdown duration that is not less than the second critical value is selected, and the number of shutdowns is equal to the number of the selected shutdown durations.

As a further optional solution to the method for determining the start-up solution of the hydrogen peroxide rocket engine catalytic bed, the second critical value is 100ms.

As a further optional solution to the method for determining the start-up plan of the catalytic bed of the hydrogen peroxide rocket engine, the n+1th start-up is corrected according to the flow and accumulation conditions in the n-th group of catalytic tests. Timing, including:

In the nth group of the catalytic test, when the product at the outlet of the shell is completely converted into pure gas phase, the number of times the valve has been closed is recorded as a, if a is less than the n+1th start-up sequence is the number of shutdowns, then the number of shutdowns in the n+1th startup sequence is modified to a, otherwise the number of shutdowns remains unchanged.

As a further optional solution to the method for determining the start-up plan of the catalytic bed of the hydrogen peroxide rocket engine, the last start-up sequence is revised again according to the flow and accumulation conditions in the last group of the catalytic tests ,include:

In the last group of the catalytic tests, when the product at the outlet of the shell is completely converted into pure gas phase, the number of times the valve has been closed is denoted as b, if b is less than the number of times in the last start-up sequence the number of shutdowns, the number of shutdowns in the last startup sequence is modified to b, otherwise the number of shutdowns remains unchanged.

As a further optional solution to the method for determining the start-up plan of the catalytic bed of the hydrogen peroxide rocket engine, the observation of the flow and accumulation of the product at the outlet end of the casing in the combustion chamber includes:

A transparent quartz glass thrust chamber is used as the combustion chamber;

arranging a high-speed camera at the exit of the combustion chamber; and

The flow and accumulation of the product at the outlet end of the casing inside the combustion chamber are observed by the high-speed camera.

As a further optional solution to the method for determining the start-up plan of the catalytic bed of the hydrogen peroxide rocket engine, after observing the flow and accumulation of the product at the outlet end of the casing in the combustion chamber, the method further includes:

A thermal imaging camera is arranged at the exit of the combustion chamber, the thermal imaging camera is the same height as the high-speed camera; and

An infrared thermal imager is used to measure the temperature distribution of the outlet of the casing and the interior of the combustion chamber.

As a further optional solution to the method for determining the start-up plan of the catalytic bed of the hydrogen peroxide rocket engine, after observing the flow and accumulation of the product at the outlet end of the casing in the combustion chamber, the method further includes:

A plurality of temperature sensors are used to measure the temperature distribution inside the head cavity and the housing.

As a further optional solution to the method for determining the start-up plan of the catalytic bed of the hydrogen peroxide rocket engine, a plurality of the temperature sensors are respectively arranged on the head cavity and the outer wall of the casing, and are located in the casing. The temperature sensors above are symmetrically distributed with respect to the axis of the housing.

The embodiments of the present invention have the following beneficial effects:

Use the bubble sheet test to simulate the decomposition of hydrogen peroxide in the rocket engine, design the valve start sequence according to the results of the bubble sheet test, conduct a catalytic test in the rocket engine according to the start sequence, and then correct the next group of catalysts according to the results of the catalytic test. The start-up sequence corresponding to the test will gradually improve the start-up sequence. Finally, the last startup sequence is revised again and used as the startup scheme. The above process can design a start-up scheme that completely matches the catalyst bed of the rocket engine, improve the start-up speed of the catalyst bed, and avoid excessive ignition pressure peaks in the combustion chamber during the ignition stage, thereby eliminating the risk of deflagration.

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, preferred embodiments are hereinafter described in detail together with the accompanying drawings.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 shows the schematic flow chart of the determination method of the hydrogen peroxide rocket engine catalytic bed startup scheme provided by the embodiment of the present invention;

2 shows a schematic flowchart of step S101 in the method for determining a hydrogen peroxide rocket engine catalytic bed startup scheme provided by an embodiment of the present invention;

3 shows a schematic structural diagram of a rocket engine provided by an embodiment of the present invention;

Fig. 4 shows the position distribution schematic diagram of observation and measurement equipment in the determination method of the hydrogen peroxide rocket engine catalytic bed startup scheme provided by the embodiment of the present invention;

FIG. 5 shows a schematic diagram of the position distribution of temperature sensors in the method for determining the starting scheme of the catalytic bed of a hydrogen peroxide rocket engine provided by an embodiment of the present invention.

Description of main component symbols:

1-head chamber; 11-pressure measuring joint; 2-catalyst bed assembly; 21-shell; 211-catalyst bed outer layer; 212-support shell; 22-catalyst bed body; 23-even flow plate; 24-baffle plate ;25-adjustment retaining ring;26-flange plate;27-sealing ring;28-head insulation ring;3-combustion chamber;4-high-speed camera;5-infrared thermal imager;6-temperature sensor;7- DV camera.

Detailed ways

The following describes in detail the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, only used to explain the present invention, and should not be construed as a limitation of the present invention.

It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. The terms "vertical," "horizontal," "left," "right," and similar expressions are used herein for illustrative purposes only.

In the present invention, unless otherwise expressly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , or integrated; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of the two elements or the interaction relationship between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terminology used herein in the specification of the template is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Example 1

Please refer to FIG. 1 and FIG. 2 together, the present embodiment provides a method for determining the start-up scheme of a hydrogen peroxide rocket engine catalytic bed (hereinafter referred to as "determination method"), and the determination method is suitable for hydrogen peroxide rocket engines with different working heights. The rocket engine with hydrogen as the oxidant is also suitable for the rocket engine with different concentrations of hydrogen peroxide as the oxidant. It can design a startup plan that completely matches the catalyst bed of the rocket engine, improve the startup speed of the catalyst bed, and avoid ignition. The combustion chamber 3 of the stage has an excessively high ignition pressure peak, thereby eliminating the risk of detonation.

Referring to FIG. 3 , the rocket engine includes a head chamber 1 , a catalytic bed assembly 2 and a combustion chamber 3 .

A pressure measuring joint 11 is arranged on the side wall of the head cavity 1 , and the pressure measuring joint 11 is hollow and tubular, and communicates with the inside of the head cavity 1 , so as to facilitate the measurement of the pressure inside the head cavity 1 . The outlet end of the head chamber 1 is directly opposite to the inlet end of the catalytic bed assembly 2, and a flow equalizing plate 23 is arranged at the boundary between the two, so that the hydrogen peroxide in the head chamber 1 can flow into the catalytic bed assembly 2 uniformly.

In addition, the inlet end of the head chamber 1 is also connected to a hydrogen peroxide supply system through a valve, and the supply system supplies hydrogen peroxide into the head chamber 1 and the catalytic bed assembly 2 . A flow regulating valve or a venturi is arranged in the supply system to regulate the volume flow of hydrogen peroxide at the valve, which are not shown in the figures.

The catalytic bed assembly 2 is composed of a catalytic bed body 22 and a shell 21 , the catalytic bed body 22 is made of silver mesh, and the shell 21 is further divided into a catalytic bed outer layer 211 and a support shell 212 . The axes of the catalytic bed body 22, the catalytic bed outer layer 211 and the support shell 212 are coincident, and the catalytic bed outer layer 211 is directly wrapped on the side of the catalytic bed body 22, and the support shell 212 is sleeved on the catalytic bed outer layer 211, Play the role of connection and support.

A stepped surface is formed on the inner wall of the outer layer 211 of the catalytic bed facing away from the head cavity 1. One end of the catalytic bed body 22 is in contact with the flow equalizing plate 23, and the other end of the catalytic bed body 22 is connected to the step through the baffle plate 24 with holes. face to face. During use, the catalyst bed body 22 is stable in the outer layer 211 of the catalyst bed and will not deviate from its original position.

The inner wall of the end of the support shell 212 facing away from the head cavity 1 is also formed with a stepped surface. . The adjusting retaining ring 25 compensates for the difference between the lengths of the outer layer 211 of the catalytic bed and the supporting shell 212 , so that the outer layer 211 of the catalytic bed can be stabilized in the supporting shell 212 .

One end of the support shell 212 is fixedly connected to the head chamber 1 by welding or bolting, and the other end of the support shell 212 is fixedly connected with a flange 26 and is bolted to the combustion chamber 3 through the flange 26 . In addition, the inner edge of the flange 26 facing the combustion chamber 3 is embedded with a head heat insulating ring 28 , and the connection between the flange 26 and the combustion chamber 3 is provided with a sealing ring 27 .

The outer edge of the head insulation ring 28 facing the combustion chamber 3 is in contact with the end face of the combustion chamber 3 , and the inner edge of the head insulation ring 28 facing away from the combustion chamber 3 is in contact with the end surface of the support shell 212 to block the combustion chamber 3 The heat inside is transferred directly to the catalytic bed assembly 2 .

Please refer to Figure 1 and Figure 2 together, the above determination method includes the following steps:

S101, multiple groups of bubble sheet tests are performed on the silver mesh to simulate the catalytic reaction process in the rocket engine, and the steps are as follows:

S101-1, sampling the silver mesh from the same production batch as the catalytic bed body 22, and cutting the silver mesh into slices with the same size and quality.

Subtle differences in the production process will lead to differences in the catalytic capacity of the produced silver mesh. The silver mesh of the same production batch as the catalytic bed body 22 is used as a sample to maximize the accuracy of the test results of the foam tablet.

S101-2, set up multiple groups of beakers, inject hydrogen peroxide into the beakers, and the concentration of hydrogen peroxide injected into the beakers is the same as the concentration of hydrogen peroxide used by the rocket engine.

Specifically, the number of beakers in each group is 8. At the same time, the same amount of hydrogen peroxide was injected into 8 beakers, and a control experiment was carried out, which could eliminate errors as much as possible and further improve the accuracy of the results of the blister test.

S101-3, put the slices into the first group of the beakers and start timing, stop timing when the hydrogen peroxide in the beaker is completely decomposed, and collect the overall quality information of the beaker through the sensor during the timing process , to get the mass change curve.

Specifically, a slice is placed in each beaker, and the sensor uses a pressure sensor to measure the total mass of the beaker, slice and hydrogen peroxide.

At each moment, the pressure sensors under each beaker collect 8 data respectively. Calculate the mode, median and average of these 8 data, compare them, and select the two with closer values as the total mass, and finally combine the time information to form the mass change curve of the first group of blister tests.

S101-4, and so on, put the slices after catalysis in the beakers of the mth group into the beakers of the m+1th group, where m is a positive integer, and repeat the process of timing and collecting quality information, And obtain the corresponding mass change curve.

Specifically, put the slices after the first group of blister tests into the second group of beakers for the blister test, and put the slices after the second group of blister tests into the third group of beakers for the blister test. And so on.

In the process of catalytic decomposition of hydrogen peroxide, the catalytic ability of the silver mesh will first gradually increase, and then tend to be stable. The blister test using the slices after the previous group of blister tests can coherently reflect the change process of the catalytic capacity of the slices, which is consistent with the change process of the catalytic bed body 22 in the rocket engine.

S101-5, setting a first critical value, and when the difference between the time lengths required for complete decomposition of the hydrogen peroxide in the adjacent two groups of the beakers is less than or equal to the first critical value, the blister test is ended.

When the difference in the time required for the complete decomposition of hydrogen peroxide in the adjacent two groups of beakers is less than or equal to the first critical value, the mass change curves of the corresponding two groups of blister tests are almost the same, indicating that the catalytic ability of the slices has become stable at this time. , and remain unchanged for a long period of time without continuing the blister test.

S102, design a first start-up sequence for the valve according to the results of the first group of the blister tests, the start-up sequence includes an opening duration, a closing duration and a number of closings, and the opening duration and the closing duration are set alternately.

Specifically, when the rocket engine is started, the valve needs to be opened first, so that the supply system can fill the head chamber 1 and the casing 21 with hydrogen peroxide, and then the valve is closed. After the hydrogen peroxide in the head chamber 1 and the casing 21 is completely decomposed, the valve is opened again, the supply system fills the head chamber 1 and the casing 21 with hydrogen peroxide again, and then the valve is closed again.

As the catalytic process progresses, the catalytic capacity of the catalytic bed body 22 is gradually increased until the rate at which the catalytic bed body 22 catalyzes the decomposition of hydrogen peroxide is equal to the rate at which the supply system injects hydrogen peroxide. At this time, the valve is no longer closed and remains normally open.

Therefore, the start-up sequence for controlling the opening and closing of the valve includes alternately set opening durations and closing durations. Taking each opening and closing of the valve as a pulse, the number of pulses is equal to the number of times the valve is closed. After the valve is kept in a normally open state, the hydrogen peroxide is no longer injected into the head chamber 1 and the housing 21 in the form of pulses.

In the actual working process, the opening and closing of the valve will lag for a certain time compared with the issuing of control commands, which is the response time of the valve action, recorded as t _v , and t _v is a constant value. Due to the existence of t _v , there is an error between the actual action of the valve and the preset start sequence. However, the error of the valve during the opening process and the error during the closing process will cancel each other, so on the whole, _tv does not affect the corresponding control system to control the valve according to the starting sequence, so it is ignored.

计算出催化床本体22内部空隙的体积为

也是催化床本体22内所能容纳的过氧化氢的体积。因此，火箭发动机内可容纳的过氧化氢的体积为V_f＝V_s+V_t2，即供应系统在单次脉冲下向头腔1和壳体21内注入的过氧化氢的体积。According to the structural size of the rocket engine, the volume of the catalytic bed body 22 is calculated and denoted as V _t1 , and the volume of the head cavity 1 is calculated at the same time, denoted as V _s . According to the porosity parameters of the silver mesh provided by the manufacturer

The volume of the void inside the catalytic bed body 22 is calculated as

It is also the volume of hydrogen peroxide that can be contained in the catalytic bed body 22 . Therefore, the volume of hydrogen peroxide that can be accommodated in the rocket engine is V _f =V _s +V _t2 , that is, the volume of hydrogen peroxide injected into the head chamber 1 and the casing 21 by the supply system under a single pulse.

On the other hand, according to the opening degree of the aforementioned flow regulating valve, or the throat diameter of the aforementioned venturi, the volume flow rate of hydrogen peroxide at the valve is calculated, which is recorded as Q _v . Finally, the time required for the supply system to fill the head chamber 1 and the housing 21 with hydrogen peroxide is calculated as t ₁ =V _f /Q _v .

Therefore, in the startup sequence, the opening duration of the valve corresponding to each pulse is t ₁ , and

According to the density of the silver mesh, the mass of the catalyst bed body 22 is calculated, which is recorded as m _c . The mass of a single slice was measured and recorded as m ₁ . According to the density ρ of hydrogen peroxide, the mass of hydrogen peroxide that can be accommodated in the rocket engine is calculated as m _f =ρ*V _f .

Assuming that the slices per unit mass have the same catalytic capacity as the catalytic bed body 22, if the hydrogen peroxide in the rocket engine is completely decomposed in the same time, the hydrogen peroxide in the beaker decreases by Δm, where Δm is the mass, and

Therefore, according to the aforementioned mass change curve, the time required for the whole mass of the beaker to decrease by Δm from the start of timing is calculated and recorded as t ₂ . t ₂ has multiple values, corresponding to multiple pulses of the rocket engine in the start-up phase, and t ₂ is the time required for the complete decomposition of hydrogen peroxide in the rocket engine under the corresponding pulse. Finally, the closing duration of the valve corresponding to each pulse is calculated as t ₃ =t ₂ -t ₁ .

With the progress of the catalytic process, the catalytic ability of the silver mesh gradually increases, t ₂ gradually decreases, and the difference between t ₂ and t ₁ becomes smaller and smaller. 100ms is set as the second critical value. When t ₃ is less than the second critical value, the valve is no longer closed and remains in a normally open state. Therefore, only t ₃ not less than the second threshold value is reserved in the startup sequence, and the number of t ₃ that meets the requirements is the number of shutdowns.

S103 , according to the first starting sequence, control the valve to open within a time period corresponding to the opening time period, and close it within a time period corresponding to the closing time period, so as to supply peroxide into the housing 21 Hydrogen, conduct the first group of catalytic tests, and observe the flow and accumulation of the product at the outlet end of the casing 21 in the combustion chamber 3 .

Specifically, an example of the startup sequence is as follows:

Table 1 valve start sequence

Among them, t _ij represents the t _i of the jth pulse.

As shown in Table 1, when the absolute time is 1000 ms, the valve is opened, and the duration of the open state is t ₁₁ . When the absolute time is 1000ms+t ₁₁ , the valve is closed, and the duration of the closed state is t ₃₁ . And so on until the valve is normally open.

Referring to FIG. 4 , in order to observe the flow and accumulation of the product at the outlet end of the casing 21 in the combustion chamber 3 , in this embodiment, a transparent quartz glass thrust chamber is used as the combustion chamber 3 , and the outlet of the combustion chamber 3 is used as the combustion chamber 3 . A high-speed camera 4 is arranged at the place.

When the rocket engine is in the starting stage, through the high-speed camera 4, the experimenter can clearly observe the flow of the gas-liquid two-phase flow and the distribution of the liquid in the combustion chamber 3, and can also clearly observe the outlet end of the casing 21 The phase transformation process of the product in the combustion chamber 3 .

In addition to observing the above flow and accumulation conditions, in this embodiment, an infrared thermal imager 5 is also arranged at the exit of the combustion chamber 3. When the rocket engine is in the start-up stage, the experimenter uses the infrared thermal imager 5 to pair the shell. The temperature distribution at the outlet of 21 and the interior of the combustion chamber 3 is measured.

Specifically, the heights of the infrared thermal imager 5 and the high-speed camera 4 are equal to ensure that the temperature distribution collected by the infrared thermal imager 5 corresponds to the flow and accumulation conditions collected by the high-speed camera 4 . In addition, the infrared thermal imager 5 and the high-speed camera 4 can be arranged on the same side of the axis of the combustion chamber 3, or can be arranged on both sides of the axis of the combustion chamber 3, respectively, and the distance between the two and the axis of the combustion chamber 3 can also be determined according to Measurement needs to adjust.

Using the infrared thermal imager 5 to measure the temperature distribution at the outlet of the casing 21 and the interior of the combustion chamber 3 , the temperature distribution of the product at the outlet end of the casing 21 can be known. The temperature change of the product at the outlet end of the casing 21 occurs at the same time as the phase transition, so the measurement result of the infrared thermal imager 5 can be used as the evidence for the observation result of the high-speed camera 4 .

Referring to FIG. 5 , in addition to observing the above-mentioned flow, accumulation and temperature distribution, in this embodiment, a plurality of temperature sensors 6 are also used to measure the temperature distribution inside the head cavity 1 and the casing 21 .

Specifically, three patch-type temperature sensors 6 are arranged on the outer wall of the head cavity 1 for measuring the temperature of the outer wall that has been cast. One of the temperature sensors 6 is located on the side of the head cavity 1 , and the other two temperature sensors 6 are symmetrically arranged on both sides of the inlet end of the head cavity 1 .

In addition, eight patch-type temperature sensors 6 are arranged on the side wall of the casing 21 for measuring the axial temperature distribution of the catalytic bed assembly 2 and comparing the temperature differences between the two sides of the catalytic bed assembly 2 . The eight temperature sensors 6 are divided into two groups of four. The two groups of temperature sensors 6 are symmetrical about the axis of the casing 21 , and the four temperature sensors 6 in the same group are arranged along the axis of the casing 21 .

On the other hand, the temperature distribution collected by the aforementioned infrared thermal imager 5 can verify the rationality of the arrangement of the aforementioned temperature sensor 6 .

With the help of these temperature sensors 6, the temperature field distribution inside the head cavity 1 and the casing 21 can be obtained, and the temperature changes inside the head cavity 1 and the casing 21 can be accurately measured during the starting process of the rocket engine.

In this embodiment, a DV camera 7 is also arranged near the outlet of the combustion chamber 3 . Choose a suitable shooting angle, so that the DV camera 7 can record the test process as completely as possible.

S104, and so on, design the n+1th start sequence for the valve according to the result of the n+1th group of the blister test, and according to the flow and accumulation conditions in the nth group of the catalytic test The n+1th start-up sequence is revised, and the n+1th group of the catalytic tests is performed according to the n+1th start-up sequence, where n is a positive integer.

The same as the design process of the first start-up sequence, using the mass change curve obtained by the n+1 group of blister tests, a series of t ₂ values in the n+1th start-up sequence can be obtained, and then a series of Closing time.

Starting from the second start-up sequence, after the start-up sequence design is completed, the start-up sequence needs to be revised according to the flow and accumulation conditions in the previous group of catalytic tests.

Specifically, in the previous set of catalytic experiments, the supply system injected hydrogen peroxide into the head chamber 1 . After passing through the equalizing plate 23 , the hydrogen peroxide flows into the catalytic bed body 22 and is catalytically decomposed. The water and oxygen generated by the reaction pass through the baffle plate 24 and then enter the combustion chamber 3 .

Since the catalytic decomposition reaction releases a large amount of heat, the catalytic products and undecomposed hydrogen peroxide are gasified. With the gradual progress of the catalytic test, the product at the outlet end of the shell 21 is gradually transformed from the liquid phase to the gas phase, and finally becomes a pure gas phase.

The number of times the valve has been closed, a, is recorded when the product has just turned into a pure gas phase. If a is less than the number of shutdowns in the current startup sequence, modify the number of shutdowns in the current startup sequence to a, otherwise the number of shutdowns remains unchanged.

After adjusting the number of pulses in the current start-up sequence using the flow and accumulation conditions in the previous group of catalytic tests, the catalytic test is performed according to the current start-up sequence. This cycle repeats until the last set of catalytic tests are completed.

When the product at the outlet end of the shell 21 is completely converted into a pure gas phase, its temperature distribution tends to be stable. If the experimenter finds that the temperature of the product at the outlet end of the casing 21 is stable through the infrared thermal imager 5, it can be proved that the product at the outlet end of the casing 21 has been completely converted into a pure gas phase.

S105 , according to the flow and accumulation conditions in the last group of the catalytic tests, correct the last start-up sequence again, and use the revised last start-up sequence as the start-up scheme.

Similar to step S104, in the last set of catalytic experiments, when the product is just transformed into pure gas phase, the number of times the valve has been closed b is recorded. If b is less than the number of shutdowns in the last startup sequence, the number of shutdowns in the last startup sequence is modified to b, otherwise the number of shutdowns remains unchanged.

Finally, the hydrogen peroxide rocket engine catalytic bed startup scheme is obtained.

The startup scheme can not only effectively reduce the use of hydrogen peroxide in the startup phase of the rocket engine, but also effectively reduce or even eliminate the accumulation of hydrogen peroxide in the combustion chamber 3, thereby effectively improving the safety of the rocket engine.

In all examples shown and described herein, any specific value should be construed as merely exemplary and not as limiting, as other examples of exemplary embodiments may have different values.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as limiting the scope of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention.

Claims (8)

1. a determination method of hydrogen peroxide rocket engine catalytic bed start-up scheme, is characterized in that, is applied to rocket engine, and described rocket engine comprises catalytic bed assembly, and described catalytic bed assembly comprises shell and is made of silver net. A catalytic bed body, the inlet end of the casing is connected with a head cavity, the outlet end of the casing is connected with a combustion chamber, the catalytic bed body is located in the casing, and the inlet end of the head cavity is connected with a valve through a valve supply system; The determination method of the hydrogen peroxide rocket engine catalytic bed startup scheme includes: Carry out multiple groups of blister tests on the silver net; Design a first start-up sequence for the valve according to the results of the first group of the blister tests, the start-up sequence includes an opening duration, a closing duration and a number of closings, and the opening duration and the closing duration are alternately set; According to the first described starting sequence, the valve is controlled to be opened within the time period corresponding to the opening duration, and closed within the time period corresponding to the closing duration, so as to supply hydrogen peroxide into the housing for the first step. A set of catalytic tests, and observe the flow and accumulation of products at the outlet end of the casing inside the combustion chamber; By analogy, according to the results of the n+1 group of the bubble sheet test, the n+1th start sequence is designed for the valve, and the nth group is revised according to the flow and accumulation in the nth group of the catalytic test. n+1 said start-up sequences, and perform the n+1th group of said catalytic tests according to the n+1th start-up sequence, where n is a positive integer; and According to the flow and accumulation conditions in the last group of the catalytic tests, the last start-up sequence is revised again, and the revised last start-up sequence is used as the start-up scheme; The described silver net is subjected to multiple groups of blister tests, including: Sampling the silver mesh from the same production batch as the catalytic bed body, and cutting the silver mesh into slices with the same size and quality; Set up multiple groups of beakers, inject hydrogen peroxide into the beakers, and the concentration of the hydrogen peroxide injected into the beakers is the same as the concentration of hydrogen peroxide used by the rocket motor; Put the slices into the first group of the beakers and start timing. When the hydrogen peroxide in the beaker is completely decomposed, the timing is ended. During the timing process, the overall quality information of the beaker is collected by the sensor, and the mass change is obtained. curve; By analogy, put the slices after catalysis in the beakers of the mth group into the beakers of the m+1th group, where m is a positive integer, repeat the process of timing and collecting quality information, and obtain the corresponding the mass change curve; and A first critical value is set, and the blister test ends when the difference between the time lengths required for complete decomposition of the hydrogen peroxide in the adjacent two groups of the beakers is less than or equal to the first critical value; The result of the blister test according to the nth group is the nth start-up sequence of the valve design, where n is a positive integer, including: Denote the volume flow of the valve as Q _v , denote the volume of the catalytic bed body as V _t1 , denote the volume of the head cavity as V _s , and according to the porosity parameter ∅ of the silver mesh provided by the manufacturer, then The turn-on duration is t ₁ =(V _s +∅* V _t1 )/Q _v ; Denote the mass of the slice as m ₁ , denote the mass of the catalytic bed body as m _c , and denote the density of hydrogen peroxide as ρ, then the time t ₂ required for the complete decomposition of hydrogen peroxide in the rocket engine is equal to the The time required for the overall mass of the beaker to decrease by Δm, and Δm=ρ*(V _s +∅* V _t1 )* m ₁ /m _c , according to the mass change curve, calculate the overall mass of the beaker since the start timing The time required for each mass reduction Δm is taken as a plurality of t ₂ , and finally a plurality of the closing time lengths t ₃ =t ₂ -t ₁ are obtained; and A second critical value is set, and only the shutdown duration that is not less than the second critical value is selected, and the number of shutdowns is equal to the number of the selected shutdown durations. 2 . The method for determining a hydrogen peroxide rocket engine catalytic bed startup scheme according to claim 1 , wherein the second critical value is 100ms. 3 . 3. the determination method of hydrogen peroxide rocket engine catalytic bed start-up scheme according to claim 1, is characterized in that, described according to the described flow and accumulation situation in the described catalytic test of the nth group, amend the n+1th The startup sequence includes: In the nth group of the catalytic test, when the product at the outlet of the shell is completely converted into pure gas phase, the number of times the valve has been closed is recorded as a, if a is less than the n+1th start-up sequence is the number of shutdowns, then the number of shutdowns in the n+1th startup sequence is modified to a, otherwise the number of shutdowns remains unchanged. 4. the determination method of the hydrogen peroxide rocket engine catalytic bed start-up scheme according to claim 1, is characterized in that, described according to the described flow and the accumulation situation in the described catalytic test of the last group, revise the last one again again. The startup sequence described above includes: In the last group of the catalytic tests, when the product at the outlet of the shell is completely converted into pure gas phase, the number of times the valve has been closed is denoted as b, if b is less than the number of times in the last start-up sequence the number of shutdowns, the number of shutdowns in the last startup sequence is modified to b, otherwise the number of shutdowns remains unchanged. 5. The method for determining a hydrogen peroxide rocket engine catalytic bed start-up scheme according to claim 1, wherein the observation of the flow and accumulation of the product at the outlet end of the casing in the combustion chamber includes the following steps: : A transparent quartz glass thrust chamber is used as the combustion chamber; arranging a high-speed camera at the exit of the combustion chamber; and The flow and accumulation of the product at the outlet end of the casing inside the combustion chamber are observed by the high-speed camera. 6. The method for determining a hydrogen peroxide rocket engine catalytic bed start-up scheme according to claim 5, characterized in that, after said observation of the flow and accumulation of the product at the outlet end of the casing in the combustion chamber, Also includes: A thermal imaging camera is arranged at the exit of the combustion chamber, the thermal imaging camera is the same height as the high-speed camera; and An infrared thermal imager is used to measure the temperature distribution of the outlet of the casing and the interior of the combustion chamber. 7. The determination method of hydrogen peroxide rocket engine catalytic bed start-up scheme according to claim 1, characterized in that, after described observing the flow and accumulation situation of the outlet end product of the casing inside the combustion chamber, Also includes: A plurality of temperature sensors are used to measure the temperature distribution inside the head cavity and the housing. 8. The method for determining a hydrogen peroxide rocket engine catalytic bed startup scheme according to claim 7, wherein a plurality of the temperature sensors are respectively arranged on the outer walls of the head cavity and the casing, and are located in the The temperature sensors on the housing are symmetrically distributed about the axis of the housing.

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