A combustion air heater for ground direct-connected test bench

Abstract

The present invention discloses a combustion-type air heater for a ground-based direct-connected test bench. The heater comprises a combustion chamber, a transition section, a tail nozzle, a gas injector, an air-oxygen mixture injector, an air-oxygen mixer, a main gas nozzle, and a secondary gas nozzle. The gas injector, air-oxygen mixture injector, combustion chamber, transition section, and tail nozzle are sequentially connected. A portion of the bottom of the air-oxygen mixture injector serves as an injection panel. The main gas nozzle penetrates the gas injector and the air-oxygen mixture injector and is inserted into the air nozzle of the injection panel, forming a first annular gap between the main gas nozzle and the air nozzle. Multiple secondary gas nozzles are evenly distributed around the main gas nozzle and are inserted into the air nozzles at corresponding positions on the injection panel, forming a second annular gap between the secondary gas nozzle and the air nozzle. The main gas nozzle and the air-oxygen mixture injector are respectively connected to the positive and negative electrodes of a high-voltage electric spark generator. The heater has the characteristics of a wide temperature range, a novel structure, and integrated ignition.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace test equipment, in particular to a combustion type air heater used for a ground direct-connection test bench. Background Art

[0002] The direct-connected test bench has the advantages of easy parameter adjustment, high testing efficiency and high safety. It is a very important ground test bench in the aerospace field. Its working principle is to directly connect the combustion chamber of the aircraft engine to the experimental device that simulates the high-altitude flight flow. By manually adjusting the parameters of the experimental device, the airflow parameters entering the combustion chamber, such as speed, composition, pressure, etc., can simulate the actual high-altitude flight airflow parameters.

[0003] At present, the experimental devices used to simulate high-altitude flight flow mainly include three types: vacuum self-priming wind tunnel, thermal storage heater and combustion heater. Vacuum self-priming wind tunnel requires the installation of a huge vacuum ball and supporting vacuum equipment after the test section, resulting in a high cost for the test bench. The maximum temperature of the thermal storage heater disclosed in the document "Progress in the Design and Construction of 1m-scale Hypersonic Wind Tunnels in Aviation Industry" is 900K, which consumes huge power and is quite expensive. See "Gao Liangjie, Xin Yanan, et al. Progress in the Design and Construction of 1m-scale Hypersonic Wind Tunnels in Aviation Industry [J]. Experimental Fluid Mechanics, 2022, 36(01): 44-51". Regarding combustion-type heaters, the invention patent with application number 201710260853.2 discloses a ground-direct-connected test air heating device for aircraft engines. The operating temperature is 600~1500K, with a small temperature span, and oxygen supplementation is required in the middle section of the combustion chamber, which not only increases the complexity of the pipeline, but also increases the equipment and control costs; due to the existence of the oxygen supplementation structure, the combustion chamber cannot be installed with a water cooling system. Multiple long-term tests will cause serious heat accumulation on the test bench, shortening the equipment life, and posing a safety hazard.

[0004] Existing combustion-type heaters usually need to be equipped with a separate igniter for starting the heater, which means that a separate air supply system and measurement and control system need to be set up, which will obviously increase the complexity and cost of the equipment. Since the separately equipped igniter needs to penetrate the outside air when the heater is started in order to contact the fuel and achieve ignition, and the air flow is quite large under low total temperature conditions, not only does it make it difficult for the flame generated by the igniter to penetrate the air, but it also causes serious turbulence in the airflow of the injection panel, making it difficult for the flame to stabilize. This is also the key reason why existing combustion-type heaters are usually difficult to achieve stable operation below a total temperature of 900K. At present, for combustion-type heaters that can span a large total temperature range, two or even more injection panels are usually required to correspond to different total temperature intervals. During variable operating condition tests, the equipment needs to be disassembled and replaced to a large extent, which not only increases the test time and cost, but also frequently disassembling and installing will shorten the life of the equipment. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a combustion-type air heater for a ground direct-connected test bench to solve the problems of the existing air heaters, such as complex structure, high test cost and small temperature span.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] A combustion air heater for a ground direct-connected test bench comprises a combustion chamber, a transfer section, a tail nozzle, a gas injector, an air-oxygen mixture injector, an air-oxygen mixer, a main gas nozzle and an auxiliary gas nozzle;

[0008] Part of the bottom area of ​​the air-oxygen mixture filler serves as an injection panel, on which a plurality of air nozzles are provided; the gas filler, the air-oxygen mixture filler, the combustion chamber, the transition section and the tail nozzle are connected in sequence; the main gas nozzle passes through the gas filler and the air-oxygen mixture filler, and is inserted into the air nozzle at the center of the injection panel, forming a first annular gap between the main gas nozzle and the air nozzle; a plurality of auxiliary gas nozzles are evenly distributed around the main gas nozzle, and each auxiliary gas nozzle is inserted into the air nozzle at the corresponding position of the injection panel, forming a second annular gap between the auxiliary gas nozzle and the air nozzle; the main gas nozzle and the air-oxygen mixture filler are respectively connected to the positive and negative poles of the high-voltage electric spark generator.

[0009] Furthermore, a gas cavity is provided in the middle of the gas filler, and a plurality of gas filling holes communicating with the gas cavity are provided on the top.

[0010] Furthermore, an air-oxygen mixture gas filler is provided with an air-oxygen mixture gas cavity in the middle, and air-oxygen mixture gas filling holes communicating with the air-oxygen mixture gas cavity are provided around it. The area at the bottom of the air-oxygen mixture gas filler facing the air-oxygen mixture gas cavity serves as an injection panel.

[0011] Furthermore, a plurality of radial gas inlets are evenly arranged around the middle of the main gas nozzle, and the gas inlets are communicated with the main flow channel of the main gas nozzle along the axial direction.

[0012] Furthermore, a gas inlet is provided on the top of the main gas nozzle, and the gas inlet is communicated with the main flow channel of the main gas nozzle along the axial direction.

[0013] Furthermore, the air-oxygen mixer includes an air duct and an oxygen duct; the air duct waist is uniformly arrayed with air holes in the circumferential direction, the outer side of the air duct waist is covered with an oxygen cavity covering all the air holes, and the oxygen duct is connected to the oxygen cavity.

[0014] Furthermore, the combustion chamber and tail nozzle are both provided with water cooling jackets.

[0015] Furthermore, the transition section is provided with a parameter measurement hole for measuring the total temperature and total pressure of the combustion chamber.

[0016] Furthermore, the upper portion and the lower portion of the main gas nozzle are respectively fixedly connected to the gas filler and the air-oxygen mixture filler through insulating sleeves.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The main gas nozzle, gas injector, air-oxygen mixture injector, and auxiliary gas nozzle together form a novel heater head cavity structure. The main gas nozzle and auxiliary gas nozzle form annular gaps with the air nozzle of the injection panel. The air-oxygen mixture is ejected from the annular gaps. The main gas nozzle achieves ignition through the tip discharge effect, which can effectively prevent high-temperature areas on the injection panel that cause panel ablation. Moreover, integrated ignition is achieved directly on the injection panel, eliminating the need for a separate igniter, reducing equipment complexity and cost. The applicable total temperature range of this air heater is 400K to 2500K, solving the problem of the limited total temperature span of existing heaters.

[0019] 2. The main gas nozzle has two configurations, suitable for different total temperature ranges. The main gas nozzle is easy to connect with the gas filler and the air-oxygen mixture filler, and is easy to disassemble and replace when conducting tests in different total temperature ranges.

[0020] 3. Air flow is high under low total temperature conditions, while it is low under high total temperature conditions. These two operating conditions require different numbers and sizes of air nozzles in the injection panel. Therefore, existing combustion-type air heaters require different injection panels to accommodate wide temperature ranges. However, the present invention only requires a single injection panel to accommodate wide temperature ranges. This simplifies the structure and avoids frequent disassembly and replacement of the equipment.

[0021] 4. The air-oxygen mixer can evenly mix air and oxygen, making the combustion flame more stable. There is no need to add oxygen supplementation equipment at the rear of the combustion chamber, which simplifies the overall structure and reduces costs. At the same time, it ensures the integrity of the combustion chamber structure, making it possible to install a water cooling system to ensure that the combustion chamber will not overheat during long-term operation of the heater, thereby extending the equipment life and improving safety.

[0022] 5. The adapter section is not only used to connect the combustion chamber and the tail nozzle, but also has parameter measurement holes on the adapter section for measuring the total temperature and total pressure of the combustion chamber, avoiding the use of upwind pressure measurement to measure the total pressure and total temperature, thereby improving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the overall structural diagram of the present invention;

[0024] Figure 2 It is a structural diagram of the injection panel of the present invention;

[0025] Figure 3 A structural diagram of the main gas nozzle of the present invention;

[0026] Figure 4 Another structural diagram of the main gas nozzle of the present invention;

[0027] Figure 5 It is a structural diagram of the air-oxygen mixer of the present invention;

[0028] Description of the drawings: 1- Main gas nozzle; 2- Gas injector; 3- Air-oxygen mixture injector; 4- Combustion chamber; 5- Adapter section; 6- Tail nozzle; 7- Air-oxygen mixer; 8- Auxiliary gas nozzle; 9- First insulating sleeve; 10- Second insulating sleeve; 11- Third insulating sleeve; 12- Clamping flange; 13- Sealing gasket;

[0029] 21-Gas filling hole; 22-Gas chamber; 31-Air-oxygen mixture filling hole; 32-Air-oxygen mixture chamber; 41-Combustion chamber water cooling outlet; 42-Combustion chamber water cooling inlet; 51-Parameter measurement hole; 61-Nozzle water cooling outlet; 62-Nozzle water cooling inlet; 71-Oxygen pipe; 72-Oxygen chamber; 73-Air pipe. DETAILED DESCRIPTION

[0030] Specific embodiments are given below in conjunction with the accompanying drawings. The specific embodiments are only used to introduce the technical solutions of the present invention in detail and are not intended to limit the scope of protection of the present application.

[0031] The present invention is a combustion air heater for a ground direct-connected test bench, comprising a main gas nozzle 1, a gas filler 2, an air-oxygen mixture filler 3, a combustion chamber 4, a transition section 5, a tail nozzle 6, an air-oxygen mixer 7, an auxiliary gas nozzle 8, a first insulating sleeve 9, a second insulating sleeve 10, a third insulating sleeve 11, and a sealing gasket 13;

[0032] The top of the gas filler 2 is provided with a plurality of axial gas filling holes 21, which are connected to the gas supply device, and a gas cavity 22 connected to the gas filling hole 21 is provided in the middle; an air-oxygen mixture gas filler 3 is provided with an air-oxygen mixture gas cavity 32 in the middle, and a plurality of radial air-oxygen mixture gas filling holes 31 are provided around the air-oxygen mixture gas filler 3, which are connected to the air-oxygen mixture gas cavity 32, and each air-oxygen mixture gas filling hole 31 is connected to the gas outlet end of the air-oxygen mixer 7; the bottom area of ​​the air-oxygen mixture gas filler 3 facing the air-oxygen mixture gas cavity 32 serves as an injection panel (see Figure 2 ), multiple air nozzles are evenly arranged on the injection panel;

[0033] The gas filler 2, the air-oxygen mixture gas filler 3, the combustion chamber 4, the adapter section 5 and the tail nozzle 6 are connected in sequence. A sealing gasket 13 is provided between the air-oxygen mixture gas filler 3 and the gas filler 2 and the combustion chamber 4 respectively. The main gas nozzle 1 is located at the center of the gas filler 2 and the air-oxygen mixture gas filler 3. After passing through the gas filler 2 and the air-oxygen mixture gas filler 3 in sequence, it is inserted into the air nozzle at the center of the injection panel. A first annular gap is formed between the outer wall of the main gas nozzle 1 and the inner wall of the air nozzle. The air-oxygen mixture is discharged from the first annular gap. The gas is ejected and mixed with the gas ejected from the main gas nozzle 1. The main gas nozzle 1, the gas filler 2, the air-oxygen mixture filler 3 and the auxiliary gas nozzle 8 together constitute the head cavity of the heater; further, the upper part of the main gas nozzle 1 is sealed with the gas filler 2 through the second insulating sleeve 10, the head of the main gas nozzle 1 is connected to the clamping flange 12 through the first insulating sleeve 9, the clamping flange 12 is fixedly connected to the end of the gas filler 2 by screws, and the lower part of the main gas nozzle 1 is connected to the air-oxygen mixture filler 3 through the third insulating sleeve 11;

[0034] Multiple auxiliary gas nozzles 8 (four in this embodiment) are evenly distributed around the main gas nozzle 1. The auxiliary gas nozzles 8 are inserted from the end face of the air-oxygen mixture injector 3, penetrate the air-oxygen mixture injector 3, and are inserted into the air nozzles at the corresponding positions of the injection panel. The air inlet of the auxiliary gas nozzle 8 is connected to the gas cavity 22 of the gas injector 2, and the gas outlet of the auxiliary gas nozzle 8 is connected to the combustion chamber 4. A second annular gap is formed between the outer wall of the auxiliary gas nozzle 8 and the inner wall of the air nozzle. The air-oxygen mixture is ejected from the second annular gap and mixed with the gas ejected from the auxiliary gas nozzle 8.

[0035] The main gas nozzle 1, the auxiliary gas nozzle 8, the air-oxygen mixture injector 3, the combustion chamber 4, the adapter section 5 and the tail nozzle 6 are all made of 304 stainless steel; the main gas nozzle 1 is connected to the positive electrode of the high-voltage electric spark generator, and the air-oxygen mixture injector 3 is connected to the negative electrode of the high-voltage electric spark generator. When the high-voltage electric spark generator is energized, a high-voltage electric spark is generated at the first annular gap formed by the main gas nozzle 1 and the corresponding air nozzle through the tip discharge effect, which ionizes and activates the air-oxygen mixture ejected from the first annular gap, and then ignites the gas ejected from the main gas nozzle 1 and forms a high-temperature flame at the main gas nozzle 1. The flame quickly spreads to the auxiliary gas nozzle 8 and ignites the gas ejected from the auxiliary gas nozzle 8, achieving ignition; the gas burns in the combustion chamber 4 to generate high-temperature flue gas, which enters the tail nozzle 6 through the adapter section 5, and then enters the downstream aircraft engine combustion chamber after accelerated expansion in the tail nozzle 6.

[0036] The main gas nozzle 1 is divided into two configurations, suitable for different total temperature ranges. Figure 3As shown, one configuration is that multiple radial gas inlets are evenly arranged around the middle of the main gas nozzle 1. The gas inlets are connected to the main flow channel along the axial direction at the center of the main gas nozzle 1. This main gas nozzle 1 is suitable for a total temperature range of 400K~1600K. During installation, it is necessary to ensure that the gas inlet of the main gas nozzle 1 is connected to the gas chamber 22 of the gas filler 2, so that the main gas nozzle 1 and the auxiliary gas nozzle 8 share the gas chamber 22. Figure 4 As shown, another configuration is that the gas inlet of the main gas nozzle 1 is located at the top, the gas inlet is connected to the main flow channel along the center axial direction, and the gas inlet is connected to the gas supply device, through which the main gas nozzle 1 is independently supplied with gas. The total temperature range applicable to this main gas nozzle 1 is 1600K~2500K.

[0037] like Figure 5 As shown, the air-oxygen mixer 7 includes an air duct 73 and an oxygen duct 71; a circle of air holes is evenly arrayed in the circumferential direction of the waist of the air duct 73, and a circle of oxygen cavity 72 is covered on the outer side of the waist of the air duct 73, and the oxygen cavity 72 covers all the air holes; the oxygen duct 71 is connected to the oxygen cavity 72, and oxygen enters the oxygen cavity 72 through the oxygen duct 71, and then enters the air duct 73 through the air holes to mix with the air to form an air-oxygen mixed gas.

[0038] The outer wall of the combustion chamber 4 is provided with a water cooling jacket, which is provided with multiple combustion chamber water cooling outlets 41 and combustion chamber water cooling inlets 42. The combustion chamber 4 is cooled by water cooling to ensure that the combustion chamber 4 will not overheat and can be operated for a long time multiple times.

[0039] The transition section 5 is connected to the combustion chamber 4 and the tail nozzle 6 via a flange connection, achieving a transition between the combustion chamber 4 and the tail nozzle 6. A graphite gasket is used to achieve a seal between the transition section 5, the combustion chamber 4, and the tail nozzle 6. Two parameter measurement holes 51 are provided in the transition section 5 for measuring the total temperature and total pressure of the combustion chamber 4.

[0040] The tail nozzle 6 is designed to accelerate the expansion of the high-temperature flue gas generated by combustion to the desired flight Mach number. Its converging surface can be designed based on the required flight Mach number to achieve a better accelerated expansion effect. The tail nozzle 6 is equipped with a water cooling jacket with multiple nozzle water cooling outlets 61 and nozzle water cooling inlets 62, ensuring that the tail nozzle 6 does not overheat and can operate stably for a long time.

[0041] The first insulating sleeve 9, the second insulating sleeve 10 and the third insulating sleeve 11 are made of polytetrafluoroethylene, which has a high breakdown voltage and good compression and self-sealing properties, so it can achieve sealing and insulation between the main gas nozzle 1 and the gas filler 2 and the air-oxygen mixture filler 3.

[0042] Example 1: Set the total temperature to 400K, the flight Mach number to 2, the incoming Mach number to 0.7, and the main gas nozzle 1 to Figure 3 The structure shown in FIG. Gas enters the gas chamber 22 through the gas filling hole 21 on the gas filler 2. Part of the gas enters the main gas nozzle 1 through the gas inlet of the main gas nozzle 1, and the other part of the gas enters each auxiliary gas nozzle 8. The main gas nozzle 1 and the auxiliary gas nozzle 8 jointly inject gas into the combustion chamber 4. Air and oxygen are mixed in the air-oxygen mixer 7 to form an air-oxygen mixture, which enters the air-oxygen mixture cavity 32 through the air-oxygen mixture filling hole 31 on the air-oxygen mixture filler 3, and then enters the combustion chamber 4 through the air nozzle on the injection panel; the high-voltage electric spark generator is energized, and through the tip discharge effect, a high-voltage electric spark is generated at the first annular gap formed by the main gas nozzle 1 and the corresponding air nozzle, ionizing and activating the air-oxygen mixture ejected from the first annular gap, igniting the gas ejected from the main gas nozzle 1 and forming a high-temperature flame at the main gas nozzle 1, and the flame quickly spreads to the auxiliary gas nozzle 8 and ignites the gas ejected from the auxiliary gas nozzle 8, achieving ignition, and at this time the heater is started; due to the low total temperature at the initial start-up stage, it is difficult for the gas to ignite directly in the air-oxygen mixture, so it is necessary to first introduce oxygen through the air-oxygen mixer 7 for ignition, and then introduce air for supplementary combustion and to cool the high-temperature flue gas. The ignition timing is as follows:

[0043] The high-voltage spark generator is started at 0s, and oxygen is introduced at 0.5s;

[0044] At 1 second, the gas is introduced, and the gas mixes with oxygen to achieve ignition;

[0045] Air is introduced at 2s. After the air is added, the total temperature of the high-temperature flue gas generated by combustion drops to the set temperature of 400K, and the heater starts to operate according to the set working conditions;

[0046] At 2.5 seconds, the high-voltage spark generator is turned off; at 7.5 seconds, the fuel gas and oxygen are stopped, the flame goes out, and the combustion process ends;

[0047] Stop supplying air at 9 seconds. Finally, stop supplying air to blow away the residual high-temperature flue gas in the heater and achieve cooling, and the work is completed.

[0048] Example 2: Set the total temperature to 2500K, the flight Mach number to 5, and the incoming Mach number to 2. Since the gas flow is large, if Figure 3 The main gas nozzle 1 is used to make the flow evenly distributed to the main gas nozzle 1 and the auxiliary gas nozzle 8, which will cause the gas flow rate at the gas nozzle outlet to be too high, making it difficult to achieve stable ignition. Therefore, the main gas nozzle 1 adopts Figure 4The gas enters the combustion chamber 4 in two ways. One way is directly through the main gas nozzle 1. The gas ejected from the main gas nozzle 1 meets the air-oxygen mixture at the first annular gap. An equivalence ratio of 0.9 to 2 ensures a high ignition success rate. The other way is to enter the gas chamber 22 of the gas filler 2 and then enter each auxiliary gas nozzle 8. Ignition in this embodiment does not require the introduction of oxygen for ignition. The ignition sequence is as follows:

[0049] The high-voltage spark generator was started at 0s, and oxygen and air were introduced at 0.5s;

[0050] At 1s, gas is introduced into the main gas nozzle 1 to achieve ignition;

[0051] At 1.5 seconds, gas is introduced into the gas chamber 22 of the gas filler 2. The high-temperature flame generated by the main gas nozzle 1 ignites the gas ejected from each auxiliary gas nozzle 8. The heater is fully started and operates according to the set working conditions.

[0052] At 2 seconds, the high-voltage spark generator is turned off; at 7 seconds, the fuel gas and oxygen are stopped, the flame goes out, and the combustion process ends;

[0053] Stop the air supply at 9 seconds.

[0054] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A combustion air heater for a ground direct-connected test bench, comprising a combustion chamber, a transition section, and a tail nozzle; characterized in that: It also includes a gas filler, an air-oxygen mixture gas filler, an air-oxygen mixer, a main gas nozzle and an auxiliary gas nozzle; a portion of the bottom area of ​​the air-oxygen mixture gas filler serves as an injection panel, and a plurality of air nozzles are provided on the injection panel; The gas filler, air-oxygen mixture filler, combustion chamber, transition section and tail nozzle are connected in sequence; the main gas nozzle passes through the gas filler and air-oxygen mixture filler, and is inserted into the air nozzle at the center of the injection panel, forming a first annular gap between the main gas nozzle and the air nozzle; Multiple auxiliary gas nozzles are evenly distributed around the main gas nozzle. Each auxiliary gas nozzle is inserted into the air nozzle at the corresponding position of the injection panel, forming a second annular gap between the auxiliary gas nozzle and the air nozzle; the main gas nozzle and the air-oxygen mixture injector are respectively connected to the positive and negative electrodes of the high-voltage electric spark generator; When the total temperature range applicable to the main gas nozzle is 400K to 1600K, a plurality of radial gas inlets are evenly arranged around the middle of the main gas nozzle, and the gas inlets are connected to the main flow channel of the main gas nozzle along the axial direction; when the total temperature range applicable to the main gas nozzle is 1600K to 2500K, a gas inlet is provided at the top of the main gas nozzle, and the gas inlet is connected to the main flow channel of the main gas nozzle along the axial direction.

2. The combustion type air heater for a ground direct-connected test bench according to claim 1, characterized in that: The middle part of the gas filler is provided with a gas cavity, and the top part is provided with a plurality of gas filling holes communicated with the gas cavity.

3. The combustion type air heater for a ground direct-connected test bench according to claim 1 or 2, characterized in that: An air-oxygen mixture cavity is provided in the middle of the air-oxygen mixture filler, and air-oxygen mixture filling holes communicating with the air-oxygen mixture cavity are provided around the air-oxygen mixture filler. The area at the bottom of the air-oxygen mixture filler facing the air-oxygen mixture cavity serves as an injection panel.

4. The combustion type air heater for a ground direct-connected test bench according to claim 1, characterized in that: The air-oxygen mixer comprises an air duct and an oxygen duct; the waist of the air duct is uniformly arrayed with air holes in the circumferential direction; the outer side of the waist of the air duct is covered with an oxygen cavity covering all the air holes; the oxygen duct is connected to the oxygen cavity.

5. The combustion type air heater for a ground direct-connected test bench according to claim 1, characterized in that: The combustion chamber and the tail nozzle are both provided with water cooling jackets.

6. The combustion type air heater for a ground direct-connected test bench according to claim 1, characterized in that: The transition section is provided with a parameter measuring hole for measuring the total temperature and total pressure of the combustion chamber.

7. The combustion type air heater for a ground direct-connected test bench according to claim 1, characterized in that: The upper part and the lower part of the main gas nozzle are connected to the gas filler and the air-oxygen mixture filler respectively through insulating sleeves.

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