CN112179664A - Adjustable low-pressure ignition experimental system for researching sub-super mixed flow - Google Patents
Adjustable low-pressure ignition experimental system for researching sub-super mixed flow Download PDFInfo
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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Abstract
The invention discloses an adjustable low-pressure ignition experimental system for researching sub-super mixed flow, which comprises an experimental section, a gas inlet, a gas outlet and a gas outlet, wherein a through mixed gas flow channel is arranged between the gas inlet and the gas outlet; the gas outlet end of the subsonic gas flow passage is connected with a first inlet of the gas inlet; the air inlet joint is connected with the air inlet end of the subsonic gas flow passage; the gas outlet end of the supersonic gas flow channel is connected with a second inlet of the gas inlet; the combustion chamber is connected with the air inlet end of the supersonic gas flow passage; the outlet flow channel is connected with the gas outlet and is provided with a heat exchange section; the back pressure adjusting mechanism is connected with the gas outlet of the outlet flow channel and is used for adjusting the back pressure of the experiment system in the experiment process in a vacuumizing mode; according to the invention, the back pressure adjusting mechanism is connected on the outlet runner, so that the back pressure of the experiment system can be adjusted according to experiment needs, the working environment of the rocket engine can be better simulated, and the back pressure adjustment of the experiment system is more accurate.
Description
Technical Field
The invention belongs to the technical field of aerospace experimental instruments, and particularly relates to an adjustable low-pressure ignition experimental system for researching sub-ultra mixed flow.
Background
In the combustion chamber of the embedded rocket type ramjet, the mixing of main rocket gas and incoming flow air is typical large-gradient sub-super-shear mixing flow, the thickness of a shear mixing layer formed between two jets is abnormally slow along with the increase of the flow direction due to large speed difference and large temperature difference between the two jets, the energy and momentum transfer between the two jets can be influenced, the overall combustion efficiency of the main rocket type ramjet is low, the fuel energy cannot be fully exerted, the working characteristics of the ramjet combined engine can be seriously influenced, and the combustion chamber becomes one of technical bottlenecks in the development of the ramjet combined engine.
Inside rocket ramjets, the convection mach number of the sub-super-shear mixed flow formed by the rocket jet and the ram-incoming flow is often above 1. The requirements of the sub-ultra shear mixing flow on the experimental device are far higher than those of the incompressible shear mixing flow, and the flow field structure of the shear mixing flow can be changed by the small disturbance of the boundary condition, which provides a serious challenge for the design of the shear mixing flow experimental device.
The commonly used experimental device is generally a sub-super shear mixed flow experimental device under the condition of normal back pressure, can carry out schlieren technical measurement on the sub-super shear mixed flow, and directly obtains the flow field structure of the sub-super shear mixed flow through the schlieren technology
However, the existing experimental device for measuring the sub-ultra-shear mixed flow is only under the condition of normal back pressure, and the high-altitude engine actually works under the condition of low back pressure, so that the existing experimental device has little reference significance for obtaining the flow field structure and the characteristics of the sub-ultra-shear mixed flow under the condition of low back pressure.
Disclosure of Invention
The invention aims to provide an adjustable low-pressure ignition experimental system for researching sub-super mixed flow, so as to provide a real simulation low back pressure condition for a sub-super shear layer in a rocket engine and improve the accuracy of experimental data.
The invention adopts the following technical scheme: an adjustable low-pressure ignition experimental system for researching sub-ultra mixed flow, comprising:
the experimental section is provided with a gas inlet and a gas outlet, and a through mixed gas flow channel is arranged between the gas inlet and the gas outlet; wherein the gas inlet comprises a first inlet and a second inlet;
the gas outlet end of the subsonic gas flow passage is connected with the first inlet;
the air inlet joint is connected with the air inlet end of the subsonic gas flow passage;
the gas outlet end of the supersonic gas flow channel is connected with the second inlet;
the combustion chamber is connected with the air inlet end of the supersonic gas flow channel and is used for providing supersonic gas;
the outlet flow passage is connected with the gas outlet of the experimental section and is provided with a heat exchange section, and the heat exchange section is used for cooling the mixed gas flowing out of the gas outlet; and
and the back pressure adjusting mechanism is connected with the gas outlet of the outlet flow channel and is used for adjusting the back pressure of the experiment system in the experiment process in a vacuumizing mode.
Furthermore, the outlet flow passage comprises a folding section and an exhaust section which are integrally formed along the flowing direction of the mixed gas, and the heat exchange section is positioned in the middle of the exhaust section;
wherein, the furling section is in a round table shape, and the cross sectional area of the inlet is larger than that of the outlet.
Furthermore, a condensation pipe is arranged in the inner cavity of the heat exchange section, the condensation pipe is a coiled pipe, and the water inlet end and the water outlet end of the condensation pipe are both arranged on the outer wall of the heat exchange section.
Furthermore, the experimental section is cuboid and is internally provided with a cavity;
the first inlet is arranged at the front end part of the chamber, and the second inlet is arranged on one side surface of the front section of the chamber;
the second inlet is provided with a flow guide pipe which is L-shaped and is positioned in the cavity, the first section of the flow guide pipe is vertical to the central line of the cavity and is connected with the outlet end of the supersonic gas flow passage, the second section of the flow guide pipe is superposed with the central line of the cavity, and the outlet of the second section of the flow guide pipe faces the gas outlet;
the second section includes relative roof and bottom plate that sets up, and roof and bottom plate extend to relative another inner wall by one inner wall of experiment section.
Furthermore, a baffle is arranged on the side wall of the experimental section, and a temperature measuring device and a pressure measuring device are installed on the baffle.
Further, the backpressure regulating mechanism comprises a vacuum tank connected with the outlet flow passage, and the vacuum tank is further connected with a vacuum pump and an exhaust pump.
Further, roof and bottom plate are the flat board, and all are provided with the arch near the honeycomb duct exit on the medial surface of roof and bottom plate, every arch to its equal smooth transition in front and back.
Further, the inlet area of the subsonic gas flow passage is smaller than the outlet area.
Further, an air inlet of the combustion chamber is connected with an air supply system;
the gas supply system comprises a first gas supply pipeline and a second gas supply pipeline which are connected in parallel, the first gas supply pipeline is used for providing oxygen for the combustion chamber, and the second gas supply pipeline is used for providing ethylene for the combustion chamber;
the first air supply pipeline and the second air supply pipeline are both connected to the same third air supply pipeline, and the third air supply pipeline is used for providing flushing gas for the air supply system.
The invention has the beneficial effects that: the invention provides supersonic gas through the combustion chamber, provides subsonic gas through the air inlet joint, mixes in the experimental section to form sub-super shear mixed flow, and is connected with the back pressure adjusting mechanism on the outlet flow passage, so that the back pressure of the experimental system can be adjusted according to experimental needs, the working environment of the rocket engine can be better simulated, and the temperature of the mixed gas discharged from the experimental section is reduced through the heat exchange section, thereby reducing the influence of the high temperature of the mixed gas on the back pressure in the experimental system, and leading the back pressure adjustment of the experimental system to be more accurate.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of the present invention;
FIG. 2 is a schematic view of another view angle corresponding to FIG. 1;
FIG. 3 is a schematic perspective view corresponding to FIG. 1;
FIG. 4 is a schematic diagram of the internal structure of an experimental section in the embodiment of the present invention;
FIG. 5 is a schematic view of a gas supply line according to an embodiment of the present invention;
fig. 6 is a schematic structural view of a draft tube in an embodiment of the invention.
Wherein: 1. an air inlet joint; 2. a first control valve; 3. a subsonic gas flow path; 4. an experimental section; 5. an outlet flow passage; 6. a second control valve; 7. a vacuum tank; 8. a combustion chamber; 9. a thermocouple; 10. a first pressure sensor;
41. a flow guide pipe; 42. mounting holes; 43. a flow guide channel; 51. a heat exchange section; 81. a second pressure sensor;
511. a water inlet; 512. a water outlet;
111. a first container; 112. a second container; 113. a third container; 114. a filter; 115. a pressure reducing valve; 116. a pneumatic valve; 117. a one-way valve; 118. an orifice plate; 119. a third pressure sensor.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The embodiment of the invention provides an adjustable low-pressure ignition experimental system for researching sub-super mixed flow, which is shown in figures 1, 2 and 3 and comprises an experimental section 4, a gas inlet and a gas outlet are arranged, and a through mixed gas flow channel is arranged between the gas inlet and the gas outlet; wherein the gas inlet comprises a first inlet and a second inlet; the gas outlet end of the subsonic gas flow passage 3 is connected with the first inlet; the air inlet joint 1 is connected with the air inlet end of the subsonic gas flow passage 3; the gas outlet end of the supersonic gas flow channel is connected with the second inlet; the combustion chamber 8 is connected with the air inlet end of the supersonic gas flow channel and used for providing supersonic gas; the outlet flow channel 5 is connected with a gas outlet of the experimental section 4, and is provided with a heat exchange section 51, and the heat exchange section 51 is used for cooling the mixed gas flowing out of the gas outlet; and the backpressure regulating mechanism is connected with the gas outlet of the outlet flow channel 5 and is used for regulating the backpressure of the experimental system in the experimental process in a vacuumizing mode.
According to the invention, supersonic gas is provided through the combustion chamber 8, subsonic gas is provided through the gas inlet joint, mixing is carried out in the experimental section to form shearing mixed flow, the back pressure adjusting mechanism is connected on the outlet runner 5, the back pressure of the experimental system can be adjusted according to experimental needs, the working environment of the rocket engine can be better simulated, and the mixed gas exhausted from the experimental section is cooled through the heat exchange section, so that the influence of the high temperature of the mixed gas on the back pressure in the experimental system is reduced, and the back pressure adjustment of the experimental system is more accurate.
The invention aims to establish an experimental system in a high-altitude low-backpressure environment to simulate the state of a rocket engine in a real working environment, and further research the flow field structure and characteristics in the environment. However, the experimental system has great difficulty, firstly, because the ground environment pressure is one standard atmosphere, it is very difficult to provide the working back pressure environment of igniting at high space time of about 0.1atm on the ground, and it is more difficult to realize the adjustment of different back pressures; secondly, the tail gas of the ignition experiment of the sub-super shear mixed flow needs to be introduced into a low-pressure environment, and the high-temperature and high-speed flow state of the tail gas has certain challenge on maintaining the back pressure environment.
Therefore, in order to fully understand the flow field characteristics of the sub-super shear mixed flow under the low back pressure condition, a low-pressure vacuum system and a circulating water cooling device are introduced, the former can provide different low-pressure environments of the sub-super shear mixed flow, and the latter can rapidly cool the gas passing through the shear flow experiment section, so that the vacuum system is more favorable for maintaining the low-pressure environment. In addition, but the quick assembly disassembly's of subsonic inlet front end setting air inlet joint, can realize carrying out the quick assembly disassembly function when different operating mode experiments. The method has important significance for deeply analyzing and researching the formation and development of the sub-super-shear mixed flow and the influence rule in the low-pressure environment.
In the embodiment of the invention, the outlet flow passage 5 comprises the closing section and the exhaust section which are integrally formed along the flowing direction of the mixed gas, the heat exchange section 51 is positioned in the middle of the exhaust section, and the mixed gas exhausted from the experiment section 4 can be rapidly cooled through the heat exchange section 51, so that the influence of high temperature on the gas pressure in the experiment system is reduced, and the vacuum system is more favorable for maintaining a low-pressure environment.
More specifically, in the embodiment, the mixed gas is cooled by a water-cooling heat exchange method, that is, a condenser pipe is arranged in an inner cavity of the heat exchange section 51, the condenser pipe is a coiled pipe, and a water inlet end and a water outlet end of the condenser pipe are both arranged on an outer wall of the heat exchange section 51 and are respectively connected to the water inlet 511 and the water outlet 512. Through the arrangement of the coiled pipe, the contact area of the mixed gas and the condensation pipe can be increased, and then the cooling efficiency is improved.
Air inlet joint 1 can adopt quick-operation joint, and its easy operation, it is convenient to change, can change different models when needing different low back pressures for the gaseous air input of subsonic speed is adjusted.
Adopt quick-operation joint for traditional control air input etc. such as through barometer, firstly, quick-operation joint has different models, and the air input of every model is unique, can change the model of demand according to the experiment needs, and second, under the size fluctuation of traditional air input regulation mode air input, be difficult to quick regulation to the air input of needs, need consume the longer time.
Specifically, in this embodiment, the furling section is in the shape of a circular truncated cone, and the cross-sectional area of the inlet is larger than that of the outlet. The change of the size of the runner is realized through the furling section, and the cross-sectional area of the runner is reduced, so that the backpressure adjusting mechanism can adjust the experimental system more easily.
In the embodiment of the present invention, the experimental section 4 is a rectangular parallelepiped and has a cavity therein, and the air inlet end of the cavity is set as the front end and the air outlet end of the cavity is set as the rear end. The first inlet is arranged at the front end part of the chamber, and the second inlet is arranged on one side surface of the front end of the chamber; a flow guide pipe 41 is arranged at the second inlet, the flow guide pipe 41 is L-shaped and is positioned in the cavity, the first section of the flow guide pipe is vertical to the central line of the cavity and is connected with the outlet end of the supersonic gas flow channel, the second section of the flow guide pipe is superposed with the central line of the cavity, and the outlet of the second section of the flow guide pipe faces the gas outlet; the second section comprises oppositely arranged top and bottom plates, both of which extend from one inner wall of the experimental section 4 to the opposite other inner wall.
In the chamber, a gas mixing space having a certain length is formed in order to be facilitated. The second entry sets up near first entrance, also is the anterior segment of cavity promptly, and then can reserve longer cavity space as the runner of mist, carries out gas mixing. Through the arrangement of the draft tube 41, the supersonic gas discharged from the outlet of the draft tube can be ensured to be consistent with the subsonic gas entering from the first inlet in flow direction, the flow direction of the supersonic gas is matched with the real environment of the rocket engine, and the experimental accuracy is improved. In addition, the draft tube 41 is located in the middle of the rectangular parallelepiped chamber. As shown in fig. 4, when performing an experiment, supersonic gas is discharged from the middle of the experimental section 4, subsonic gas is discharged from the upper and lower sides of the supersonic gas, and then a shear mixed flow can be formed and measured, finally achieving the purpose of the experiment.
As a possible implementation manner, in the embodiment of the present invention, as shown in fig. 6, the top plate and the bottom plate of the draft tube 4 are both flat plates, and the inner side surfaces of the top plate and the bottom plate near the outlet of the draft tube 41 are both provided with protrusions, and each protrusion smoothly transitions to the front and the back of the protrusion.
The built-in flow guide pipe 41 plays a role in accelerating the high-temperature fuel gas into supersonic velocity air flow, and plays a more critical role in a special test condition of low back pressure, namely, the influence of the back pressure environment is limited to be transmitted upstream, and the pressure in the combustion chamber 8 is stabilized, so that the ignition is smooth (or the pressure stabilizing effect is achieved). When the ethylene and the oxygen are mixed and ignited, the pressure has great influence on whether the ignition is smoothly carried out, and the lower the pressure is, the more difficult the ignition is. Under the condition of extremely low back pressure of the experimental system, when the back pressure is maintained at 0.1atm, if the pressure of the mixed gas in the combustion chamber 8 is influenced by the back pressure and is under the extremely low mixed pressure, the success of ignition is greatly disturbed, and even the ignition cannot be successful. Also, in the combustion chamber 8, a second pressure sensor 81 is provided for detecting the pressure in the combustion chamber 8.
The existence of the built-in draft tube 41 perfectly solves the problem, mixed gas is introduced into the combustion chamber 8, the mixed gas passes through the bent part (namely the joint of the first section and the second section) of the built-in draft tube 41, the flow velocity reaches the sound velocity due to the congestion effect of the gas flow, and after the mixed gas continuously flows to the second section of the draft tube 41, the gas flow is continuously accelerated to further reach the supersonic velocity state. In the supersonic regime, any disturbances downstream of the flow do not propagate upstream along the flow. Therefore, even if a low-pressure environment exists downstream, such low-pressure disturbance does not propagate into the combustion chamber 8 to affect the pressure environment of the combustion chamber 8.
In the embodiment of the invention, in order to realize observation and measurement of the gas in the chamber, the side wall of the chamber is provided with the baffle plate, the baffle plate is arranged on the experimental section in a sealing manner, and the baffle plate is provided with the temperature measuring device and the pressure measuring device. The thermocouple 9 is selected as the temperature measuring device, the through hole is formed in the baffle, the measuring end of the thermocouple 9 extends into the through hole to measure the temperature of gas, and the specific setting position of the thermocouple can be selected according to actual experiment environments. The pressure measuring device is embodied as a first pressure sensor 10, the location of which is also selected according to the actual experimental environment. The first pressure sensor 10 and the thermocouple 9 are connected in an external control system, and data acquisition is carried out through the external control system. In the embodiment of the present invention, the back pressure adjusting mechanism includes a vacuum tank 7 connected to the outlet flow passage 5, and the vacuum tank 7 is further connected to a vacuum pump and an exhaust pump. The experiment system is vacuumized through the vacuum pump and the exhaust pump, and the environmental requirement of low back pressure can be further met. However, because the air inlet of the experimental system comprises a supersonic velocity gas inlet and a subsonic velocity gas inlet, and the air outlet is the outlet flow channel 5, when the experimental system is vacuumized to manufacture a low back pressure environment, the low back pressure environment can be influenced by the size proportion of the vacuum irrigation 7 and the air inlet, if the volume of the vacuum irrigation 7 is too large, the working time of the vacuum pump is too long, the experimental efficiency is low, if the volume of the vacuum tank 7 is too small, the influence factors of the air inlet on the low back pressure environment in the experimental system can be increased, and the difficulty in controlling the low back pressure environment of the experimental system is increased.
More specifically, vacuumThe volume of the tank 7 is selected to be 3m3The vacuum tank 7 with the volume specification is selected because the pressure of the vacuum tank 7 is extremely difficult to maintain in the test process due to the over-small volume; the back pressure in the vacuum tank 7 is adjusted mainly by controlling the pumping time of the vacuum pump, and the volume is too large, so that the pumping time of the vacuum tank is too long, and the variable pressure control of the vacuum tank 7 is difficult to realize; furthermore, the vacuum tank 7 is too large, the sealing conditions become more and more severe, and a great deal of effort is required for equipment maintenance.
In an embodiment of the present invention, the subsonic gas flow passage 3 has an inlet area smaller than an outlet area, specifically, the inlet end is in a circular tube shape and is suitable for being connected with the first control valve 2, and the outlet end is in a circular truncated cone shape, so as to realize diameter change between the first control valve 2 and the experimental section 4. The first control valve 2 is selected as a vacuum ball valve, and the sealing performance of the whole system is improved.
In one embodiment of the invention, the air inlet of the combustion chamber 8 is connected with an air supply system; the gas supply system comprises a first gas supply pipeline and a second gas supply pipeline which are connected in parallel, and the first gas supply pipeline and the second gas supply pipeline are used for providing raw material gas for the combustion chamber 8; in particular, a first air supply line is used to provide oxygen to the combustion chamber 8 and a second air supply line is used to provide ethylene to the combustion chamber 8. The first air supply pipeline and the second air supply pipeline are both connected to the same third air supply pipeline, and the third air supply pipeline is used for providing flushing gas for the air supply system.
More specifically, as shown in fig. 5, the first gas supply line includes a first container 111 for storing a 30% oxygen gas source, and is configured by installing a control valve in front of the parallel connection point to realize a main-standby state, and further includes a filter 114, a pressure reducing valve 115, a pneumatic valve 116, a check valve 117, and an orifice 118 in sequence, and is finally connected to the oxygen inlet of the combustion chamber 8. And, all be provided with the manometer between each component to detect each part of pipeline and each component, increase the security performance.
The second gas supply line is connected in the same manner as the first gas supply line, except that the first vessel 111 is replaced by a second vessel 112, the second vessel 112 being used to store a source of ethylene gas.
In this embodiment, third pressure sensors 119 are mounted on both sides of the orifice plate 118 for monitoring the gas flow pressure of each gas supply line to achieve precise regulation of the gas supply lines.
In addition, a third air supply pipeline is further arranged and is used for flushing the experiment system after the experiment is finished, and gas residues in the system are avoided. Specifically, the third gas supply line includes two third containers 113 capable of storing nitrogen therein, a filter 114 and a pressure reducing valve 115 are sequentially disposed on the third gas supply line to realize gas filtration and pressure regulation, after passing through the pressure reducing valve 115, the gas flows to the first gas supply line and the second gas supply line respectively, specifically, the gas is connected between the check valve 117 and the orifice plate 118, the nitrogen can be prevented from reversely flowing to the first container 111 or the second container 112 through the check valve, and secondary filtration of the gas can be realized through the orifice plate 118.
The experimental system provided by the embodiment of the invention is used for researching the sub-super-shear mixed flow, realizes the ground feasibility test of the sub-super-shear mixed flow with the embedded rocket ramjet as the background, and can realize the purposes of controlling the back pressure environment of the sub-super-shear flow and changing the inflow condition only by simply controlling the suction time of the mechanical pump and replacing experimental parts, thereby realizing the experimental research of the sub-super-shear mixed flow under different inflow states and different back pressure environments under the low back pressure condition.
The adopted technical scheme is that a vacuum system is introduced and hermetically connected with an outlet of a sub-super shear mixed flow experiment device, a low back pressure environment of the sub-super shear flow experiment is realized by a method of rapidly cooling a connecting section through a circulating water cooling device, experiment working conditions can be set according to experiment requirements, a subsonic flow state in the experiment process is changed by replacing different caliber flow valves, and the low back pressure environment in the experiment process is changed by adjusting the suction time of a mechanical pump.
The working process of the invention is that a vacuum pump is opened to pump a vacuum tank 7 to a low back pressure environment, then a vacuum tank ball valve (namely a second control valve 6) and a subsonic inlet vacuum ball valve (namely a first control valve 2) are opened, air enters an experimental section from the atmospheric environment through the subsonic inlet vacuum ball valve under the pumping action of a vacuum pumping system, subsonic airflow is formed at the upper side and the lower side of the experimental section, after the subsonic airflow is stabilized, 30 percent of oxygen and ethylene pipeline electromagnetic valves are opened through a PLC control box to introduce the gas into a gas generator, a high-frequency igniter is opened to ignite the gas, high-temperature and high-pressure airflow generated after combustion generates supersonic airflow through a built-in spray pipe of the experimental section, and the sub-super-two airflows are sheared and mixed in the experimental section to form high-temperature and high-speed sub-super-shear mixed flow (the temperature is more than or equal to 900K, the speed is less than, and introducing the cooled gas into a vacuum tank 7, wherein the experiment duration is 20 s.
More specifically, the test procedure through the test system is as follows:
stage one (system hot trial preparation)
(1) And testing whether the acquisition system is normal.
(2) And cutting off the gas source valves of the 30% oxygen path and the ethylene path, and checking whether the two paths of electromagnetic valves work normally.
(3) Before each ignition test, whether the firearm works normally is checked.
(4) The pressure of the 30% oxygen gas source is adjusted to be between 1.95 and 2.17MPa, and the pressure of the ethylene gas source is adjusted to be between 0.97 and 1.15 MPa.
(5) Before the test starts, the subsonic inlet valve is closed, and the vacuum tank valve is opened for inspection to determine that the test system is good in air tightness.
(6) And starting the refrigerator to cool the connecting pipeline between the experimental section 4 and the vacuum tank 7 in advance.
(7) The vacuum pump is started to pump the pressure in the vacuum tank 7 to below 1000 Pa.
Stage two (thermal test)
(1) Starting a test section acquisition system and starting to acquire data;
(2) manually opening a control valve and a subsonic inlet valve between the vacuum tank 7 and the experimental section 4, and rapidly evacuating experimental personnel;
(3) after the test personnel are determined to leave, the 30% oxygen path electromagnetic valve is opened, the ethylene path electromagnetic valve is opened after 1s, and the igniter is opened for ignition after 1 s.
(4) After the ignition is successful, the 30% oxygen path and ethylene path electromagnetic valve are closed after 7s, the supply of fuel gas and oxygen is cut off, and the combustion is stopped.
(5) The subsonic inlet valve is continuously opened, and the mechanical Roots pump extracts ambient air to blow away the fuel gas in the vacuum tank 7.
(6) The mechanical pump was turned off and the subsonic inlet valve and vacuum tank valve were closed.
Stage three (post-treatment process of heat test)
After the thermal test, the collected data are led out from the test system and then read through Origin post-processing software, and the combustion chamber 8 measures the voltage value of the thermocouple 9 and converts the voltage value into values such as a temperature value, total pressure and static pressure of a subsonic inlet, ignition pressure of a vacuum tank, pressure of the combustion chamber, temperature of shear mixing flow of a test section and the like. And obtaining a temperature distribution curve of the shear mixing flow, and calculating to obtain the thickness and the thickness growth rate of the shear mixing flow.
The initial purpose of the design of the experimental system is to provide a low back pressure environment for the ground test of the large-gradient sub-ultra-shear mixed flow and solve the problems of high-temperature gas treatment and subsonic side airflow control caused by introducing the low back pressure environment. Therefore, the introduction of the vacuum tank 7 as a low-backpressure environment and the cooling of the high-temperature tail gas by a circulating water cooling mode are one of the key points, and under the condition, the pressure of 0.1-0.2 atm can be maintained in the vacuum tank with limited volume for testing for 20 s. The second key point is that the subsonic airflow flow is controlled through the subsonic inlet quick-mounting interface, so that the flow velocity of a subsonic side is controlled, and the convection Mach number of the shear mixed flow in the test is changed.
The experimental system is a large-gradient sub-super shear layer experimental system capable of providing a low back pressure environment on the ground. The pressure of the vacuum tank can be adjusted by controlling the time for starting the vacuum pump, and the method can be used for researching the influence rule of different back pressures on the large-gradient sub-super shear layer; the quick connector of the subsonic inlet can be quickly replaced, the air inlet flow of the subsonic inlet is changed through the size of the hole diameter of the quick connector, the flow velocity of subsonic air flow at the subsonic side is further changed, and the method can be used for researching the influence rule of different convection Mach numbers on the large-gradient subsonic-super shear layer.
Claims (9)
1. An adjustable low-pressure ignition experimental system for researching sub-super mixed flow, which is characterized by comprising:
the experimental section (4) is provided with a gas inlet and a gas outlet, and a through mixed gas flow channel is arranged between the gas inlet and the gas outlet; wherein the gas inlet comprises a first inlet and a second inlet;
a subsonic gas flow channel (3) having an outlet end connected to the first inlet;
the air inlet joint (1) is connected with the air inlet end of the subsonic gas flow passage (3);
the gas outlet end of the supersonic gas flow channel is connected with the second inlet;
the combustion chamber (8) is connected with the air inlet end of the supersonic gas flow channel and is used for providing supersonic gas;
the outlet flow channel (5) is connected with a gas outlet of the experimental section (4) and is provided with a heat exchange section (51), and the heat exchange section (51) is used for cooling the mixed gas flowing out of the gas outlet; and
and the back pressure adjusting mechanism is connected with a gas outlet of the outlet flow channel (5) and is used for adjusting the back pressure of the experiment system in the experiment process in a vacuumizing mode.
2. The adjustable low-pressure ignition experimental system for researching sub-super mixed flow as claimed in claim 1, wherein the outlet flow channel (5) comprises a converging section and an exhaust section which are integrally formed along the flow direction of the mixed gas, and the heat exchange section (51) is located in the middle of the exhaust section;
the gathering section is in a round table shape, and the cross sectional area of an inlet of the gathering section is larger than that of an outlet of the gathering section.
3. The adjustable low-pressure ignition experiment system for researching sub-super mixed flow as claimed in claim 2, wherein a condenser tube is arranged in the inner cavity of the heat exchange section (51), the condenser tube is a coil tube, and the water inlet end and the water outlet end of the condenser tube are both arranged on the outer wall of the heat exchange section (51).
4. The adjustable low-pressure ignition experiment system for researching sub-super mixed flow as claimed in claim 2 or 3, wherein the experiment section (4) is cuboid-shaped and internally provided with a chamber;
the first inlet is arranged at the front end part of the chamber, and the second inlet is arranged on one side surface of the front section of the chamber;
a flow guide pipe (41) is arranged at the second inlet, the flow guide pipe (41) is L-shaped and is positioned in the cavity, the first section of the flow guide pipe is vertical to the central line of the cavity and is connected with the outlet end of the supersonic gas flow channel, the second section of the flow guide pipe is superposed with the central line of the cavity, and the outlet of the second section of the flow guide pipe faces the gas outlet;
the second section comprises a top plate and a bottom plate which are arranged oppositely, and the top plate and the bottom plate both extend to the other opposite inner wall from one inner wall of the experimental section.
5. The adjustable low-pressure ignition experiment system for researching sub-super mixed flow as claimed in claim 4, wherein a baffle is arranged on the side wall of the experiment section, and a temperature measuring device and a pressure measuring device are mounted on the baffle.
6. The adjustable low-pressure ignition experimental system for researching sub-super mixed flow as claimed in claim 5, wherein the back pressure adjusting mechanism comprises a vacuum tank (7) connected with the outlet flow channel (5), and the vacuum tank (7) is further connected with a vacuum pump and an exhaust pump.
7. The adjustable low-pressure ignition experimental system for researching sub-ultra mixed flow as claimed in claim 4 or 5, characterized in that the top plate and the bottom plate are both flat plates, and the inner side surfaces of the top plate and the bottom plate are provided with protrusions near the outlet of the draft tube (41), and each protrusion smoothly transits to the front and the back of the protrusion.
8. The adjustable low-pressure ignition experimental system for studying sub-ultra mixed flow as claimed in claim 7, characterized in that the subsonic gas flow passage (3) has an inlet area smaller than an outlet area.
9. The adjustable low-pressure ignition experimental system for researching sub-super mixed flow as claimed in claim 8, characterized in that the air inlet of the combustion chamber (8) is connected with an air supply system;
the gas supply system comprises a first gas supply pipeline and a second gas supply pipeline which are connected in parallel, the first gas supply pipeline is used for supplying oxygen to the combustion chamber (8), and the second gas supply pipeline is used for supplying ethylene to the combustion chamber (8);
the first air supply pipeline and the second air supply pipeline are both connected to the same third air supply pipeline, and the third air supply pipeline is used for providing flushing gas for the air supply system.
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