CN106568802A - A free-jet type supersonic gas flow enthalpy steady-state measuring device - Google Patents

Abstract

The invention discloses a free-jet type supersonic gas flow enthalpy steady-state measurement device comprising: the test device and the protective cover; wherein, the test device is connected with the protective cover, and the test device is used for The gas flow enthalpy value is measured, and the protective cover is used to protect the test device. The measuring device of the invention can work for a long time in a harsh thermal environment where the total incoming flow temperature is greater than 3000K and the heat flux density is greater ^than 20MW/m2.

Description

A free-jet type supersonic gas flow enthalpy steady-state measuring device

technical field

The invention relates to the field of aircraft thermal protection systems, in particular to a free-jet type supersonic gas flow enthalpy steady-state measuring device.

Background technique

With the rapid development of my country's hypersonic vehicle industry, the design reliability of the vehicle's thermal protection system has gradually become a key issue restricting the success of the hypersonic vehicle design. The verification of the design reliability of the thermal protection system largely depends on the ground heat protection test as technical support. As one of the most important assessment methods for ground heat protection tests, the high-temperature gas flow test can generate a high-temperature supersonic gas flow free jet flow field, which has a large flow field area and low test cost. Scheme screening, performance assessment and product acceptance test. The free jet flow field of hypersonic gas flow is a non-uniform flow field, and it is very important to understand the characteristics of the flow field for the formulation of the verification test scheme and the analysis of the test results for the reliability of the thermal protection system design. The main simulation parameters of free jet flow field of hypersonic gas flow are heat flux density, pressure and enthalpy. The high temperature and high pressure environment in the flow field will cause serious damage to the measuring device, and it is relatively difficult to measure the enthalpy under the condition that the total temperature of the incoming gas flow is greater than 3000K and the heat flux density is greater than 20MW/m ² . How to ensure the survivability of the enthalpy test equipment under the condition of free jet flow of gas flow, minimize the impact of the test model on the shape and quality of the flow field, and obtain more accurate test results is an urgent problem for the designers of the ground heat protection test plan question.

At present, the enthalpy test methods and equipment for high temperature supersonic air flow are mostly used in the environment of high temperature supersonic air flow generated by arc heaters. For air, the enthalpy is only a function of temperature and pressure, which can be easily obtained with existing thermodynamic data tables or approximate formulas. For gas, the enthalpy value is not only related to temperature and pressure, but also related to the composition of the fuel and the residual oxygen coefficient. At the same time, the hypersonic free-jet gas flow generation equipment used to carry out aircraft heat insulation tests is still blank.

Contents of the invention

The technical problem solved by the present invention is: compared with the prior art, a free-jet type supersonic gas flow enthalpy steady-state measurement device is provided, so that the measurement device can work for a long time when the total temperature of the incoming flow is greater than 3000K and the heat flux density is greater than 20MW/ ^m2 harsh thermal environment.

The object of the present invention is achieved through the following technical solutions: a free-jet type supersonic gas flow enthalpy steady-state measuring device, comprising: a test device and a protective cover; wherein, the test device is connected with the protective cover, and the test The device is used to measure the gas flow enthalpy value, and the protective cover is used to protect the test device.

In the free-jet type supersonic gas flow enthalpy steady-state measurement device, the test device includes a head water jacket, a water inlet ring, a gas sampling tube, a cooling water insulation jacket for the sampling tube, a water outlet ring, a sonic nozzle, a first thermocouple , a pressure sensor, a second thermocouple, a third thermocouple and an exhaust pipe; wherein, one end of the gas sampling pipe is connected to the center of the head water jacket, and the other end is connected to the gas resident chamber; The front end interface of the water inlet ring is connected to the head water jacket, wherein the water inlet ring is sleeved on the gas sampling pipe; one end of the cooling water insulation sleeve of the sampling pipe is connected to the rear end of the water inlet ring The interface is connected, wherein, the cooling water insulation sleeve of the sampling pipe is set on the gas sampling pipe; the water outlet ring is connected with the other end of the cooling water insulation sleeve of the sampling pipe; the second thermocouple is arranged on the sampling pipe The third water channel between the inner side of the insulating water jacket and the outer side of the gas sampling pipe is connected to the first water pipe in the water outlet ring; the third thermocouple is arranged on the inner side of the insulating water jacket of the sampling pipe and the outer side of the gas sampling pipe The position where the third water channel between is connected with the second water pipe in the head water jacket, wherein the second water pipe in the head water jacket is connected with the third water pipe in the water inlet ring ; One end of the sonic nozzle is connected to the gas chamber on the rear side of the water outlet ring, and the other end is connected to the exhaust pipe; the first thermocouple is connected to the gas chamber on the rear side of the water outlet ring; the pressure sensor It is connected with the gas chamber on the rear side of the water outlet ring.

In the above-mentioned free-jet type supersonic gas flow enthalpy steady-state measuring device, the front-end interface of the water inlet ring is connected to the head water jacket, wherein, the front-end interface of the water inlet ring is connected to the head water jacket. A sealing ring is provided between them.

In the free-jet type supersonic gas flow enthalpy steady-state measurement device, one end of the cooling water insulation sleeve of the sampling tube is connected to the rear end of the water inlet ring, wherein one end of the cooling water insulation sleeve of the sampling tube is connected to the A sealing ring is arranged between the water inlet rings of the said heads.

In the free-jet type supersonic gas flow enthalpy steady-state measurement device, the water outlet ring is connected to the other end of the sampling tube cooling water insulation jacket, wherein the water outlet ring is connected to the other end of the sampling tube cooling water insulation jacket. A sealing ring is arranged between one end.

In the above-mentioned free-jet type supersonic gas flow enthalpy steady-state measuring device, the protective cover includes: a head water-cooling jacket, a body water-cooling jacket, a deflector and a connecting ring; wherein the head water-cooling jacket is sleeved on the The front end of the test device, and matches the outer contour of the head water jacket and the outer contour of the water outlet ring at the front end of the test device, and the head water cooling jacket is connected with the connecting ring welded on the water outlet ring, wherein the A first water channel is opened inside the head water-cooling jacket; the body water-cooling jacket is sleeved on the cooling water insulation jacket of the sampling tube, one end of the body water-cooling jacket is connected with the connecting ring of the water outlet ring, and the other end is connected with the The deflectors are connected, wherein a second water channel is opened inside the body water cooling jacket.

The free-jet type supersonic gas flow enthalpy steady-state measurement device further includes: a bracket; the bracket is connected to the protective cover.

In the free-jet type supersonic gas flow enthalpy steady-state measuring device, the test device further includes a cooling water flowmeter, wherein the cooling water flowmeter is connected to the first water pipe in the water outlet ring.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The free-jet type supersonic gas flow enthalpy steady-state measuring device of the present invention has stronger survivability, utilizes the flow field thermal environment isolation function of the outer layer head water-cooling jacket, body water-cooling jacket and deflector plate, can Work for a long time in harsh thermal environment conditions where the total temperature of the incoming gas flow is greater than 3000K and the heat flux density is greater ^than 20MW/m2;

(2) The free-jet type supersonic gas flow enthalpy steady-state measurement device designed by the present invention has a head water jacket and a heat-insulating sleeve heat protection assembly for the sampling tube, which can better shield the high-temperature gas flow field for gas sampling during the test process The interference of heat transfer heat of gas cooling water for sampling in the pipe improves the test accuracy.

(3) The guide cover of the free jet type supersonic gas flow enthalpy steady-state measurement device designed by the present invention can ensure that the quality of the flow field formed during the free jet flow of the gas flow is not damaged during the test process.

(4) The data results obtained by using the free-jet type supersonic gas flow enthalpy steady-state measuring device designed by the present invention can be used as the basis for judging the accuracy of the numerical calculation results of the high-temperature supersonic gas flow field.

(5) The data results obtained by using the free-jet type supersonic gas flow enthalpy steady-state measurement device designed in the present invention can be further used in the research of engineering calculation methods such as analyzing the thermophysical properties of gas.

Description of drawings

Fig. 1 is the structural representation of the free-jet type supersonic gas flow enthalpy steady-state measuring device of the present invention;

Fig. 2 is the structural representation of testing device of the present invention;

Fig. 3 is the structural representation of protective cover of the present invention;

Fig. 4 is a schematic diagram of the principle of the free-jet hypersonic gas flow test of the present invention.

detailed description

Below in conjunction with accompanying drawing, the present invention is described in further detail:

Fig. 1 is a structural schematic diagram of a free-jet type supersonic gas flow enthalpy steady-state measuring device of the present invention. As shown in FIG. 1 , the free-jet type supersonic gas flow enthalpy steady-state measurement device includes: a test device 5 and a protective cover 6 ; wherein the test device 5 is connected to the protective cover 6 .

The free-jet type supersonic gas flow enthalpy steady-state measuring device of this embodiment is based on the principle of a total calorimeter, an endothermic calorimeter that takes a small amount of gas samples from the measured high-temperature gas flow. Among them, the test device 5 is used to capture and cool a small amount of gas samples, and indirectly measure parameters such as the temperature rise of the cooling water of the gas sampling pipe 9, the flow rate of the gas samples, the total pressure and the total temperature of the gas samples, which is the core part of the test device. The protective cover 6 is used to protect the internal test device 5, so that it can work for a long time in a harsh thermal environment where the total incoming temperature is greater than 3000K and the heat flux is greater than 20MW/m ² .

The free-jet type supersonic gas flow enthalpy steady-state measurement device in this embodiment is suitable for the heat-proof structure in the high-temperature supersonic gas flow field environment: a multi-layer water-cooled structure is used during the test to ensure that the measurement device can work for a long time at the total temperature of the incoming flow. Severe thermal environment greater than 3000K and heat flux greater than 20MW/m ² .

In the above embodiment, as shown in Figure 2, the test device 5 includes a head water jacket 7, a water inlet ring 8, a gas sampling pipe 9, a cooling water insulation jacket 10 for the sampling pipe, a water outlet ring 11, a sonic nozzle 12, a first thermoelectric Couple 13, pressure sensor 14, second thermocouple 15 and third thermocouple 16; wherein, one end of the gas sampling pipe 9 is connected with the center of the head water jacket 7, and the other end is connected with the gas station 111; The front end interface of the ring 8 is connected to the head water jacket 7, wherein the water inlet ring 8 is set on the gas sampling pipe 9; one end of the cooling water insulation jacket 10 of the sampling pipe is connected to the rear end interface of the water inlet ring 8, wherein, The sampling pipe cooling water heat insulation jacket 10 is set on the gas sampling pipe 9; the water outlet ring 11 is connected with the other end of the sampling pipe cooling water heat insulation jacket 10;

The second thermocouple 15 is arranged at the position where the third water channel 190 between the inner side of the insulating water jacket 10 of the sampling tube and the outer side of the gas sampling tube 9 is connected to the first water tube 110 in the water outlet ring 11 . Specifically, the second thermocouple 15 is installed at the outlet of the cooling water downstream of the third water channel 190 between the inner side of the insulating water jacket 10 of the sampling pipe and the outer side of the gas sampling pipe 9, and is also located in the first water pipe 110 in the water outlet ring 11. , the temperature of the cooling water flowing through the position of the second thermocouple 15 can be measured by using the second thermocouple 15 .

The third thermocouple 16 is arranged at the position where the third water passage 190 between the inner side of the sampling pipe insulating water jacket 10 and the outer side of the gas sampling pipe 9 is connected to the second water pipe 710 in the head water jacket 7, wherein the head The second water pipe 710 in the water jacket 7 is connected with the third water pipe 810 in the water inlet ring 8 . Specifically, the temperature of the cooling water flowing through the position of the third thermocouple 16 can be measured by using the third thermocouple 16 .

One end of the sonic nozzle 12 is connected with the gas storage chamber 111 on the rear side of the water outlet ring 11 , and the other end is connected with the exhaust pipe 21 . Specifically, the left end of the sonic nozzle 12 is connected to the gas storage chamber 111 at the rear side of the water outlet ring 11 , and the right end of the sonic nozzle 12 is connected to the inlet of the exhaust pipe 21 .

The first thermocouple 13 is connected to the gas storage chamber 111 on the rear side of the water outlet ring 11 . As shown in FIG. 2 , the first thermocouple 13 is arranged in the test port 1111 of the gas storage chamber 111 , and the first thermocouple 13 is used to measure the temperature of the gas entering the test port 1111 from the gas storage chamber 111 .

The pressure sensor 14 is connected with the gas storage chamber 111 on the rear side of the water outlet ring 11 . Specifically, the pressure of the gas storage chamber 111 can be measured by the pressure sensor 14 .

Specifically, as shown in Figure 2, cooling water is poured into the opening at the lower end of the third water pipe 810 in the water inlet ring 8, and then enters the second water pipe 710 in the head water jacket 7. When the cooling water flows through the head water jacket 7 The position where the second water pipe 710 in the interior is connected with the third water channel 190 is divided into two branches, wherein, one stream flows upwards through the second water pipe 710 and the third water pipe 810 and finally is discharged from the opening at the upper end of the third water pipe 810; The branch flow flows into the third water channel 190 , flows backward into the first water pipe 110 in the water outlet ring 11 , and then is discharged from the upper and lower openings of the first water pipe 110 . Utilize the third thermocouple 16 to measure the temperature of the cooling water flowing through the third thermocouple 16 position, that is, the water inlet temperature T1, and utilize the second thermocouple 15 to measure the temperature of the cooling water flowing through the second thermocouple 15 position That is, the outlet water temperature T2. The cooling water temperature rise is calculated by the water inlet temperature and the water outlet temperature, and finally the specific heat capacity of the water is multiplied by the temperature rise of the cooling water and then multiplied by the mass flow rate of the water to obtain the heat transfer h1.

When working, that is, when the test device 5 is in the high-temperature gas flow field, part of the gas enters the gas sampling pipe 9, and first uses the third water channel 190 between the outside of the gas sampling pipe 9 and the inside of the sampling pipe cooling water insulation jacket 10 to cool. The water cools the high-temperature gas captured in the gas sampling pipe 9 , the cooled gas enters the gas storage chamber 111 , and uses the first thermocouple 13 to measure the temperature of the gas in the gas storage chamber 111 .

The captured high-temperature gas is cooled to a lower temperature that can be directly measured by the first thermocouple 13, and at the same time, the third thermocouple 16 and the second thermocouple 15 are used to measure the temperature of the gas taken away by reducing the temperature of the gas in the gas sampling pipe 9. Heat (the specific description process will be described below), and the superposition of the two is the enthalpy value of the high-temperature gas sample.

Due to the long response time of the temperature rise of the cooling water and the need for the enthalpy steady-state measurement device of this embodiment to be in a thermal equilibrium state, in order to avoid the test device being in the gas flow field with harsh conditions such as high temperature and high pressure for a long time, it is necessary to use cooling water to Its protective jacket 6 is cooled. The test method of this embodiment belongs to the steady-state measurement method. Therefore, this embodiment has a wider test range, and can perform steady-state measurement of the total enthalpy of the gas flow field under the condition of 5000-9000 kJ/kg.

The measurement process is divided into two parts: energy exchange h1 and energy residual h2. When measuring the energy exchange h1, firstly, the high-temperature gas enters the gas sampling pipe 9 to exchange heat with the cooling water in the third water channel 190 between the outside of the gas sampling pipe 9 and the inside of the sampling pipe cooling water heat insulation jacket 10, using the third The thermocouple 16 measures the inlet water temperature T1, and uses the second thermocouple 15 to measure the outlet water temperature T2. The difference between the two is the heat (cooling water temperature rise) taken away by the aforementioned reduction of the gas temperature in the gas sampling pipe 9 . Afterwards, the cooling water heat insulation jacket 10 of the sampling tube is used to protect the cooling water in the third water channel 190 from exchanging energy with the external environment during the above-mentioned cooling water temperature rise test, so that it can measure the first temperature under the condition of no heat loss and stable and balanced heat exchange. The cooling water flow Q flowing out of a water pipe 110, and the gas sample flow rate entering the gas resident chamber 111 is measured with the sonic nozzle 12 and the pressure sensor 14 Check the cooling water specific heat C _{p water} at the corresponding temperature, then you can get the enthalpy value of the energy exchange part When measuring the energy residual h2, use the first thermocouple 13 to measure the gas residual temperature T3, and combine the gas specific heat fitting formula to obtain the gas specific heat C _P that varies with the local gas flow field pressure, temperature and residual oxygen coefficient On the basis of _gas , the enthalpy value h2=C _{P gas} ·T3 of the residual part of energy can be obtained. The sum of the two is the enthalpy value H=h1+h2 of the incoming gas flow, and the unit is J/kg.

Both the test device 5 and the protective cover 6 are made of red copper with good thermal conductivity. Before use, the gas sampling pipe 9 should be welded on the sampling port at the center of the head water jacket 7, then the head water jacket 7 and the water inlet ring 8 should be connected through threads and sealing rings, and then the third thermocouple 16 and The sampling pipe cooling water insulation sleeve 10 of the second thermocouple 15 is screwed on the rear interface of the water inlet ring 8 through threads and sealing rings, and finally the water outlet ring 11 with the sonic nozzle 12, the first thermocouple 13 and the pressure sensor 14 is installed. The thread and sealing ring are screwed to the tail port of the cooling water heat insulation sleeve 10 of the sampling tube, and the internal test device 5 is assembled. In this embodiment, a sealing ring is provided so that the connection has good airtightness.

In the above-mentioned embodiment, as shown in Figure 3, the protective cover 6 includes: a head water cooling jacket 17, a body water cooling jacket 18 and a deflector 19; wherein,

The head water cooling jacket 17 is sleeved on the front end of the test device 5, and matches the outer contour of the head water jacket 7 at the front end of the test device 5 and the outer contour of the water outlet ring 8, and the head water cooling jacket 17 is welded on the water outlet ring 8. The connecting ring 22 is connected to each other, wherein a first water channel 171 is opened inside the head water cooling jacket 17 . Specifically, the inner wall of the head water cooling jacket 17 fits closely with the outer contour of the head water jacket 7 at the front end of the test device 5 and the outer contour of the water outlet ring 8, the connecting ring 22 is welded on the water outlet ring 8, and the connecting ring 22 is connected with the screw 23. The ring 22 is connected with the left end of the head water jacket 7 (as shown in FIG. 1 ). A first water channel 171 is provided inside the head water cooling jacket 17 , and cooling water is injected into the first water channel 171 to isolate the gas flow field from the test device 5 and provide thermal protection for the test device 5 . During the working process, the force direction of the incoming flow of high-temperature supersonic gas is perpendicular to the front surface of the head water cooling jacket 17, and the axial force generated by this force prevents the head water cooling jacket 17 from being separated from the internal test device 5 and firmly fits it. Water-cooled jacket 18 front ends at the body.

The body water cooling jacket 18 is sleeved on the sampling tube cooling water heat insulation jacket 10, one end of the body water cooling jacket 18 is connected with the connecting ring 22 of the water outlet ring 8, and the other end is connected with the deflector 19, wherein the body water cooling jacket The inside of 18 is provided with a second water channel 181 . Specifically, cooling water is injected from the second water channel 181 inside the body water-cooling jacket 18 , and the body water-cooling jacket 18 can isolate the gas flow field, thereby providing thermal protection for the test device 5 . The screw head at the bottom of the head water-cooling jacket 17 is inserted into a circle of connection holes reserved at the front end of the body water-cooling jacket 18 and is fixedly connected. During the test, under the frontal impact of the high-temperature, high-pressure supersonic gas flow, the axial force along the front surface of the head water-cooling jacket 17 makes the head water-cooling jacket 17 and body water-cooling jacket 18 tightly connected. The second water channel 181 inside the body water cooling jacket 18 passes through the through hole provided by the deflector 19 to weld the body water cooling jacket 18 and the deflector 19 . It should be understood that the body water cooling jacket 18 in FIG. Cooling water is injected into the opening of the second water channel 181, and then flows into the lower part of the second water channel 181 through the annular water channel, and then flows out from the opening at the bottom, as shown in Figure 3, the upper part of the second water channel 181 It is parallel to the lower part of the second water channel 181 .

Specifically, as shown in FIG. 1 , the protective sheath 6 wraps the test device 5 therein, thereby isolating the test device 5 from the gas flow field, and effectively protecting the test device 5 from heat.

The working principle of the protective cover 6 in this implementation is the water-cooled structure of the copper jacket, which provides thermal protection for the test device 5 and effectively isolates the high-temperature thermal environment of the high-temperature supersonic free-jet gas flow field, so that the test device 5 can work for a long time in harsh conditions. in a hot environment. The high thermal conductivity of copper is used to quickly transfer the high-temperature gas energy in the gas flow field to the cooling water, and the rapid flow of the cooling water is used to discharge the heat.

In the above embodiment, the free-jet type supersonic gas flow enthalpy steady-state measurement device further includes a bracket, the bracket is connected to the deflector, and the bracket is screwed to the deflector.

In the above embodiment, the test device 5 further includes a cooling water flow meter, wherein the cooling water flow meter is connected to the first water pipe 110 in the water outlet ring 11 . Specifically, the cooling water flowmeter is connected to the two openings of the first water pipe 110, and the water flow rate of the water outlet ring 11 is measured by the cooling water flowmeter. The mass flow rate of the cooling water of the sampling gas, and then the total energy h1 of the first part of the high-temperature gas taken away by the cooling water is calculated through the specific heat capacity of the cooling water at constant pressure and the temperature difference between the front and rear ends of the gas sampling pipe 9 .

Fig. 4 is a schematic diagram of the principle of the free-jet hypersonic gas flow test of the present invention. As shown in Figure 4, the free-jet type supersonic gas flow enthalpy steady-state measurement device is fixed at a fixed position in the gas flow field through a bracket 20, first connected to the liquid flow meter on the water outlet pipe downstream of the water outlet ring 11, and then connected to the pressure sensor 14 and supporting test cables for the first thermocouple 13, the second thermocouple 15, and the third thermocouple 16. When the oxidant and combustion agent flow through the injector 1 and are mixed and combusted in the combustion chamber 2, and the combustion products pass through the Laval nozzle 3 to generate a high-temperature free-jet supersonic gas flow, the free-jet supersonic gas flow enthalpy steady-state measuring device The required parameters can be measured, and the measured enthalpy value H can be calculated after post-processing to select the plateau data.

The fitting formula of gas specific heat is:

When T<1750K, the gas specific heat is:

Cp=578.78322+ ^126.19794T 0.29125-541.16222log(α);

When T≥1750K and Cp<2000J/kgK, the gas specific heat is:

In the formula, α is the gas residual oxygen coefficient, T is the gas temperature, and P is the gas pressure.

When T<1750K, the maximum relative error of gas specific heat is 5.035%, and when T>1750K, the maximum relative error of gas specific heat is 1.167%.

The free-jet type supersonic gas flow enthalpy steady-state measurement device of the present invention has strong survivability, and can work for a long time by utilizing the flow field thermal environment isolation function of the outer head water-cooling jacket, body water-cooling jacket and deflector ^In the harsh thermal environment conditions where the total temperature of the incoming gas flow is greater than 3000K and the heat flux density is greater than 20MW/m2; the free-jet type supersonic gas flow enthalpy steady-state measuring device designed by the present invention has a water jacket at the head and a thermal insulation jacket for the sampling tube The protective component can better shield the interference of the high-temperature gas flow field on the heat transfer heat of the sampling gas cooling water in the gas sampling pipe during the test, and improve the test accuracy; and the deflector of the present invention can ensure that the gas will not be damaged during the test. The quality of the flow field formed in the free jet flow process; the data results obtained by testing the free jet supersonic gas flow enthalpy steady-state measuring device in the present invention can be used as the basis for judging the accuracy of the numerical calculation results of the high temperature supersonic gas flow field; and the present invention The data obtained through the free-jet type supersonic gas flow enthalpy steady-state measurement device can be further used in the research of engineering calculation methods such as analyzing the thermophysical properties of gas.

The above-described embodiments are only preferred specific implementations of the present invention, and ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. The utility model provides a free jet formula supersonic speed gas flow enthalpy steady state measuring device which characterized in that includes: a testing device (5) and a protective sleeve (6); wherein,

the testing device (5) is connected with the protective sleeve (6), the testing device (5) is used for measuring the enthalpy value of the gas flow, and the protective sleeve (6) is used for protecting the testing device (5).

2. The free jet supersonic gas flow enthalpy steady-state measuring device of claim 1, characterized in that: the testing device (5) comprises a head water jacket (7), a water inlet ring (8), a gas sampling tube (9), a sampling tube cooling water heat insulation sleeve (10), a water outlet ring (11), a sonic nozzle (12), a first thermocouple (13), a pressure sensor (14), a second thermocouple (15), a third thermocouple (16) and an exhaust pipe (21); wherein,

one end of the gas sampling pipe (9) is connected with the center of the head water jacket (7), and the other end of the gas sampling pipe is connected with a gas stagnation chamber (111);

the front end interface of the water inlet ring (8) is connected with the head water jacket (7), wherein the water inlet ring (8) is sleeved on the gas sampling pipe (9);

one end of the sampling pipe cooling water heat insulation sleeve (10) is connected with the rear end interface of the water inlet ring (8), wherein the sampling pipe cooling water heat insulation sleeve (10) is sleeved on the gas sampling pipe (9);

the water outlet ring (11) is connected with the other end of the sampling tube cooling water heat insulation sleeve (10);

the second thermocouple (15) is arranged at the position where a third water channel (190) between the inner side of the sampling tube heat insulation water jacket (10) and the outer side of the gas sampling tube (9) is connected with the first water pipe (110) in the water outlet ring (11);

the third thermocouple (16) is arranged at a position where a third water channel (190) between the inner side of the sampling tube heat insulation water jacket (10) and the outer side of the gas sampling tube (9) is connected with a second water pipe (710) in the head water jacket (7), wherein the second water pipe (710) in the head water jacket (7) is connected with a third water pipe (810) in the water inlet ring (8);

one end of the sonic nozzle (12) is connected with a gas resident chamber (111) at the rear side of the water outlet ring (11), and the other end of the sonic nozzle is connected with an exhaust pipe (21);

the first thermocouple (13) is connected with a fuel gas resident chamber (111) at the rear side of the water outlet ring (11);

the pressure sensor (14) is connected with a gas stagnation chamber (111) at the rear side of the water outlet ring (11).

3. The free jet supersonic gas flow enthalpy steady-state measuring device of claim 2, characterized in that: one end of the gas sampling pipe (9) is welded at the center of the head water jacket (7).

4. The free jet supersonic gas flow enthalpy steady-state measuring device of claim 2, characterized in that: the front end interface of the water inlet ring (8) is connected with the head water jacket (7), wherein a sealing ring is arranged between the front end interface of the water inlet ring (8) and the head water jacket (7).

5. The free jet supersonic gas flow enthalpy steady-state measuring device of claim 2, characterized in that: one end of the sampling tube cooling water heat insulation sleeve (10) is connected with the rear end of the water inlet ring (8), wherein a sealing ring is arranged between one end of the sampling tube cooling water heat insulation sleeve (10) and the water inlet ring (8).

6. The free jet supersonic gas flow enthalpy steady-state measuring device of claim 2, characterized in that: the water outlet ring (11) is connected with the other end of the sampling tube cooling water heat insulation sleeve (10), wherein a sealing ring is arranged between the water outlet ring (11) and the other end of the sampling tube cooling water heat insulation sleeve (10).

7. The free jet type supersonic gas flow enthalpy steady-state measuring device according to one of claims 1 to 6, characterized in that: the protective sleeve (6) comprises: a head water cooling jacket (17), a body water cooling jacket (18), a guide plate (19) and a connecting ring (22); wherein,

the head water cooling jacket (17) is sleeved at the front end of the testing device (5) and matched with the outer contour of the head water jacket (7) at the front end of the testing device (5) and the outer contour of the water outlet ring (8), the head water cooling jacket (17) is connected with a connecting ring (22) welded on the water outlet ring (8), and a first water channel (171) is formed in the head water cooling jacket (17);

the body water cooling jacket (18) is sleeved on the sampling pipe cooling water heat insulation jacket (10), one end of the body water cooling jacket (18) is connected with a connecting ring (22) of the water outlet ring (8), the other end of the body water cooling jacket is connected with the guide plate (19), and a second water channel (181) is formed in the body water cooling jacket (18).

8. The free jet type supersonic gas flow enthalpy steady-state measuring device according to any one of claims 1 to 6, further comprising: a support; the support is connected with the protective sleeve (6).

9. The free jet type supersonic gas flow enthalpy steady-state measuring device according to one of claims 2 to 6, characterized in that: the testing device (5) further comprises a cooling water flow meter, wherein the cooling water flow meter is connected with a first water pipe (110) in the water outlet ring (11).