CN103743571B - Air Heating Apparatus for Long-Term Supersonic Combustion - Google Patents

Abstract

The invention discloses an air heating device for long-time supersonic combustion, which includes a nozzle plate, a combustion chamber, a round-to-square contraction tube, a nozzle pipe and an igniter. Several nozzles are arranged on the nozzle plate for injecting hydrogen into the combustion chamber and the coaxial jet nozzle of oxygen-enriched air, the combustion chamber is in the shape of a tube, the two ends of which are respectively equipped with a nozzle plate and a round-to-square shrinkage tube, and a nozzle pipe is installed on the square end of the round-to-square shrinkage tube, and the combustion chamber An igniter nozzle is provided on the tube wall close to the nozzle plate, and the igniter communicates with the combustion chamber through the igniter nozzle to spray the ignition flame into the combustion chamber. There are cooling water circulation channels between the two layers of tube walls, and the outer tube walls of the two are equipped with water inlets and outlets, and the nozzles are also provided with cooling water circulation channels, water inlets and outlets. . The invention solves the unsatisfactory problems of the existing air heating device in terms of duration and the like.

Description

Air Heating Apparatus for Long-Term Supersonic Combustion

technical field

The invention relates to an air heating device for long-term supersonic combustion.

Background technique

The scramjet engine is the core of hypersonic air-breathing propulsion technology, and has good application prospects in the fields of aerospace and national defense. At present, scramjet technology is going from laboratory research to engineering development and flight demonstration stage, which requires scramjet to conduct a large number of long-term demonstration experiments on the ground.

At present, research on supersonic combustion is mainly carried out with direct-coupled scram model engines, usually using passive cooling of thick-walled metal materials to cool the temperature of the mechanism, and the running time is relatively short, generally no more than 10 seconds.

The supersonic combustion test bench is the basic tool for supersonic combustion experiment research. The ability and level of the test bench are mainly reflected in the total temperature, total pressure conditions, duration, flow scale and operation control accuracy, reliability and automation degree that the air heating device can provide; Spontaneous ignition requires a certain range of Mach number, static pressure, static temperature and total temperature and total pressure of the gas in the combustion chamber, but the existing air heating device is not ideal in terms of duration.

Contents of the invention

Aiming at the problem that the existing air heating device is not ideal in terms of duration, etc., the present invention provides an air heating device for long-term supersonic combustion.

In order to achieve the above object, the technical scheme of the present invention is as follows:

An air heating device for long-time supersonic combustion, which includes a nozzle plate, a combustion chamber, a round-to-square contraction tube, a nozzle and an igniter. The nozzle plate is provided with several nozzles for injecting hydrogen into the combustion chamber and A coaxial jet nozzle for oxygen-enriched air, the combustion chamber is in the shape of a tube, and a nozzle plate and a round-to-square shrink tube are respectively installed at both ends of the round-to-square shrink tube. An igniter nozzle is provided on the tube wall of the chamber near the nozzle plate, and the igniter communicates with the combustion chamber through the igniter nozzle to spray the ignition flame into the combustion chamber. The combustion chamber and the round variable square shrinkage tube are both Double-layer tube wall structure, there are cooling water circulation channels between the two layers of tube walls, and the outer tube walls of both are provided with water inlets and water outlets, and the nozzles are also provided with cooling water circulation channels and Water inlet and outlet.

In order to ensure sufficient mixing and high-efficiency combustion of hydrogen and air, preferably, the length of the combustion chamber is 1 to 2 times the turbulent mixing length of adjacent nozzles on the nozzle plate in a non-combustion state.

Preferably, the igniter includes an air inlet disk, a mixed combustion tube and a flame outlet section, the air inlet disk and the flame outlet section are respectively installed at both ends of the mixed combustion pipe, and a spark plug, Five air inlets and one hydrogen inlet, the spark plug is located in the center of the intake disk, five air inlets and one hydrogen inlet are located on the same circle centered on the spark plug, one of the air inlets is on the center line of the tail hole The centerlines of the tailholes of the hydrogen inlet and one hydrogen inlet are all at an angle of 45° to the axis of the mixed combustion tube, and the centerlines of the two tailholes intersect, and the centerlines of the tailholes of the other four air inlets are all at an angle of 21° angle, and the center lines of the four tail holes intersect, the flame outlet section is trumpet-shaped, and its small end is provided with a flame outlet, and the flame outlet is connected to the igniter nozzle on the combustion chamber.

Preferably, the nozzle plate, the combustion chamber, the round-to-square contraction tube, the nozzle pipe and the igniter are all made of stainless steel with a Chinese brand name of 1Cr18Ni9C.

In order to measure the temperature and pressure in the igniter, preferably, a temperature measuring port and a pressure measuring port are also provided on the flame outlet section.

In order to measure the temperature and pressure in the air heating device, preferably, a temperature measuring nozzle and a pressure measuring nozzle are also provided on the transition section of the round-to-square shrink tube.

In order to shorten the length of the nozzle and reduce the heat loss of the air flow, preferably, the profile of the supersonic section of the nozzle is designed using the Foelsch method.

The nozzle plate of the present invention uses coaxial jet nozzles to spray hydrogen and oxygen-enriched air to the combustion chamber, which can not only cool the nozzle, but also form a distance between the flame and the wall surface, which can effectively reduce the heat flow of the wall surface; the combustion chamber, the circle and the square shrink The cooling effect of the circulating water active cooling structure of the pipe and nozzle can meet the long-term supersonic combustion ground test; The loss is small, which solves the problem that the existing air heating device is not ideal in terms of duration and the like.

Description of drawings

Fig. 1 is the structural representation of an embodiment of the air heating device for long-time supersonic combustion of the present invention;

Fig. 2 is a schematic structural view of the nozzle plate shown in Fig. 1;

Fig. 3 is a schematic structural view of the coaxial jet nozzle shown in Fig. 2;

Fig. 4 is the schematic diagram of the combustion chamber shown in Fig. 1;

Fig. 5 is a schematic diagram of the round-to-square shrink tube shown in Fig. 1;

Fig. 6 is the schematic diagram of nozzle shown in Fig. 1;

Fig. 7 is a schematic diagram of the igniter shown in Fig. 1;

In the figure: 1. Nozzle disc; 11. Coaxial jet nozzle; 111. Nozzle center; 112. Annular channel; 2. Combustion chamber; 21. Ignition nozzle; Nozzle; 32, pressure measuring nozzle; 4, nozzle; 5, igniter; 51, intake disk; 510, spark plug; 511, air inlet; 512, hydrogen inlet; 52, mixed combustion tube; 53, outlet Flame section; 530, flame outlet; 531, temperature measuring port; 532, pressure measuring port.

detailed description

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined arbitrarily with each other.

As shown in Figure 1, the air heating device for long-time supersonic combustion of the present embodiment includes a nozzle plate 1, a combustion chamber 2, a round-to-square contraction tube 3, a nozzle 4 and an igniter 5, and the nozzle plate is provided with There are several coaxial jet nozzles for injecting hydrogen and oxygen-enriched air into the combustion chamber. The combustion chamber 2 is in the shape of a tube, and its two ends are respectively equipped with a nozzle plate 1 and a round-to-square shrink tube 3. The round-to-square shrink tube 3 A nozzle 4 is installed at the square mouth end, and an igniter nozzle 21 is arranged on the tube wall of the combustion chamber 2 close to the nozzle plate 1, and the igniter 5 communicates with the combustion chamber 2 through the igniter nozzle 21 to spray into the combustion chamber 2. The ignition flame, the combustion chamber 2 and the round-to-square contraction tube 3 are all double-layer tube wall structures, and there are cooling water circulation channels between the two tube walls of the two, and the outer tube walls of the two are provided with water inlets and The water outlet and nozzle 4 are also provided with a cooling water circulation channel, a water inlet and a water outlet, and the combustion chamber 2, the round-to-square contraction tube 3 and the nozzle 4 are actively cooled by circulating water.

The air heating device adopts the method of "burning hydrogen and supplementing oxygen" to make the oxygen content in the syngas flow equal to that of normal air. The ignition method adopts a small fire to lead to a large fire. According to the requirements of simulated flight Mach number 6-7 and cooling loss, the technical indicators of the air heating device are set as follows: maximum total temperature T=2200K, maximum total pressure P=5MPa, maximum flow rate 2kg/s. Using CEA (chemical equilibrium with application) software to calculate, the composition and parameters of hydrogen-air combustion gas at various design total temperatures can be obtained, as shown in Table 1. It can be seen from the table that, for T=2200K, the molar ratio of air components after combustion is N ₂ :O ₂ :H ₂ O=47:20.9:29.5, the average molecular weight μ=26, and the gas constant R=320.

Table 1 Hydrogen air combustion parameter table (2kg/s flow rate)

Preferably, the nozzle plate 1, the combustion chamber 2, the round-to-square contraction tube 3, the nozzle 4 and the igniter 5 are all made of stainless steel with a Chinese brand name of 1Cr18Ni9C.

Nozzle plate 1

Due to the high overall temperature of the air, the fuel and air injection mechanism adopted by the conventional air heating device is difficult to withstand a long period of operation. For this reason, the present invention adopts the coaxial jet nozzle design, hydrogen is injected through the nozzle center 111 of the coaxial jet nozzle 11, and the oxygen-enriched air mixed with oxygen is injected into the combustion chamber through the outer annular passage 112. In this way, on the one hand, the nozzle can be cooled by the air and hydrogen flow, and at the same time, the combustion flame formed by the mixing of the two air flows has a certain distance from the wall surface, which can effectively reduce the heat flux on the wall surface. In order to reduce the heat load of a single nozzle, multiple nozzles are actually used to form a nozzle plate, as shown in Figure 2-3.

combustion chamber 2

In order to ensure sufficient mixing and high-efficiency combustion of hydrogen and air, the length of the combustion chamber 2 is 1 to 2 times the length of the turbulent mixing of adjacent nozzles on the nozzle plate in the non-combustion state. In this embodiment, the combustion chamber 2 adopts a circular tube design with an inner diameter of Φ220 mm and a length of 600 mm, as shown in FIG. 4 .

Round to square shrink tube 3

From a round mouth of Φ220mm to a square mouth of 70mm×70mm; in order to measure the temperature and pressure in the air heating device, a temperature measuring nozzle 31 and a pressure measuring nozzle 32 are also provided on the transition section of the round to square shrink tube 3, As shown in Figure 5.

Nozzle 4

The entire nozzle is designed in two dimensions.

Assuming that the total air temperature loss due to the cooling of the mixed combustion tube and the round-to-square contraction tube is about 300-400K, the total temperature at the throat of the nozzle is about 1800K, and the static temperature is about 850K. Using the CEA (chemical equilibrium with application) program to further calculate, the mixture is in the temperature range (800-1800K), and the air specific heat ratio γ from the heater is about 1.26-1.33. When actually designing a supersonic nozzle, take the average value γ=1.3. According to the isentropic flow relationship, the flow field parameters under the design Mach number condition can be obtained, as shown in Table 2. The actual design parameters of this embodiment are the combustion chamber inlet height of 50mm, the nominal throat height of 16.93mm, and the corresponding nozzle outlet size (H×W) of 50mm×70mm. According to the isentropic relationship, the nominal throat size of the supersonic nozzle can be obtained as shown in Table 2.

Table 2 isentropic flow parameter table, γ=1.3

Calculated at a total temperature of 1800K, the flow rate per unit area (mm ² ) of the throat under unit total pressure (MPa) is:

m＝0.6673×106× ^10－6 /(319.8×1800) ^0.5 ＝ ^0.8795 × ^10－3 kg/s

From this, the flow rates of combustion chambers with various cross-sectional sizes and Mach numbers under various incoming total pressures can be calculated, as shown in Table 3. Under the total incoming pressure of 1.13 MPa and 1.8 MPa, the air flow rate of the nozzle is about 1.2 and 1.9 kg/s, respectively. Since the air heat loss cannot be accurately predicted, the air flow rate is subject to the actual measurement value.

Table 3 Flow relationship table of supersonic nozzle

M=2.5 nozzle is used, and the nozzle outlet size (H×W) is 50mm×70mm. The profile of the supersonic section of the nozzle is designed by the Foelsch method to shorten the length of the nozzle and reduce the heat loss of the airflow; the design of the subsonic section adopts a monotonous contraction method, as shown in Figure 6. The total length of the nozzle is 200mm.

Igniter 5

As shown in Figure 7, the igniter 5 includes an air intake disk 51, a mixed combustion tube 52 and a flame outlet section 53, the mixed combustion tube 52 is tubular, and the air intake disk 51 and the flame outlet section 53 are installed on both sides of the mixed combustion tube 52 respectively. At the air intake disk 51, there are a spark plug 510, five air intake ports 511 and a hydrogen intake port 512. On the same circle with the spark plug 510 as the center, the center line of the tail hole of one of the air inlet 511 and the center line of the tail hole of a hydrogen inlet 512 are at an angle of 45° with the axis of the mixed combustion tube 52, and the two tail holes The center lines intersect, and the center lines of the tail holes of the other four air inlets 511 form an angle of 21° with the axis of the mixing combustion tube 52, and the center lines of the four tail holes intersect, and the flame outlet section 53 is trumpet-shaped, and its small end is set A flame outlet 530 is provided, and the flame outlet 530 is connected with the igniter nozzle 21 on the combustion chamber 2 .

Preferably, the flame outlet section 53 is also provided with a temperature measuring port 531 and a pressure measuring port 532 .

The above-mentioned igniter 5 refers to the design of the liquid rocket engine, and has stable performance. The air intake disk 51 adopts jet nozzles that collide with each other, and mutual collision is beneficial to mixing and complete combustion. A small stream of hydrogen and air inlets for ignition is located next to the inner layer of the spark plug 510 , and the two streams intersect in front of the spark plug 510 . In order to prevent the spark match 510 and the intake disc 51 from being burned out, the intersecting place of hydrogen gas and air for ignition has a certain distance from the intake disc 51. Air enters through five connected Φ2mm air inlets 511, and hydrogen enters the mixed combustion tube through one Φ2mm hydrogen inlet 512.

The nozzle plate of the present invention uses coaxial jet nozzles to spray hydrogen and oxygen-enriched air to the combustion chamber, which can not only cool the nozzle, but also form a distance between the flame and the wall surface, which can effectively reduce the heat flow of the wall surface; the combustion chamber, the circle and the square shrink The cooling effect of the circulating water active cooling structure of the pipe and nozzle can meet the long-term supersonic combustion ground test; The loss is small, which solves the problem that the existing air heating device is not ideal in terms of duration and the like.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. the air heating apparatus for long-time supersonic combustion, it is characterized in that: comprise spray nozzle plate, firing chamber, circle change side collapsible tube, jet pipe and lighter, described spray nozzle plate is provided with several for spraying the coaxial jet nozzle of hydrogen and oxygen-enriched air in firing chamber, described firing chamber in a tubular form, its two ends are separately installed with spray nozzle plate and circle change side collapsible tube, the square opening end of described circle change side collapsible tube is provided with jet pipe, the tube wall of the close spray nozzle plate of described firing chamber is provided with lighter and connects mouth, described lighter connects mouth and combustion chamber by lighter, to spray into pyrophoric flame to firing chamber, described firing chamber, circle change side collapsible tube is double-layer tube wall structure, cooling water circulation passage is all had between the double-layer tube wall of the two, and the outer wall of the two is provided with water inlet and water delivering orifice, described jet pipe is also provided with cooling water circulation passage and water inlet and water delivering orifice.

2. the air heating apparatus for long-time supersonic combustion according to claim 1, it is characterized in that: described lighter comprises air inlet disk, mixed combustion pipe and go out flame section, described air inlet disk and go out the two ends that flame section is arranged on mixed combustion pipe respectively, described air inlet disk is provided with a spark plug, five enter air scoop and one enter hydrogen mouth, spark plug is positioned at the central authorities of air inlet disk, five are entered air scoop and one and enter on the same circle that hydrogen mouth is positioned at centered by spark plug, one of them enters the uropore center line angle all at 45 ° with the axis of mixed combustion pipe that the uropore center line of air scoop and enter hydrogen mouth, and this two uropores center line intersects, other four uropore center lines entering air scoop all become 21 ° of angles with the axis of mixed combustion pipe, and this four uropores center line intersects, described go out flame section flare, its small end is provided with flame-out port, and this flame-out port connects mouth with the lighter on firing chamber is connected.

3. the air heating apparatus for long-time supersonic combustion according to claim 1, is characterized in that: the length of described firing chamber is 1 ~ 2 times without adjacent nozzle turbulent closure scheme length on spray nozzle plate under fired state.

4. the air heating apparatus for long-time supersonic combustion according to claim 1, is characterized in that: described spray nozzle plate, firing chamber, circle change side collapsible tube, jet pipe and lighter are made by the stainless steel material that the Chinese trade mark is 1Cr18Ni9C.

5. the air heating apparatus for long-time supersonic combustion according to claim 2, is characterized in that: described in go out in flame section to be also provided with temperature-measuring port and pressure tap.

6. the air heating apparatus for long-time supersonic combustion according to claim 1, is characterized in that: the transition section of described circle change side collapsible tube is also provided with thermometric and connects mouth and pressure tap.

7. the air heating apparatus for long-time supersonic combustion according to claim 1, is characterized in that: described jet pipe supersonic speed segment type line adopts Foelsch method design.