A high-energy spark plug-based combustion stability evaluation device

Abstract

The application discloses a combustion stability evaluation device based on high-energy spark plug, which comprises a heat-releasing disturbance device; the heat-releasing disturbance device comprises a longitudinal disturbance spark plug and a transverse disturbance spark plug; the longitudinal disturbance spark plug is used for evaluating the longitudinal combustion stability of a circular or rectangular model engine, and is preferably arranged in the front half of the combustion chamber in the longitudinal direction; the transverse disturbance spark plug is used for evaluating the transverse combustion stability of the rectangular model engine; and the transverse disturbance spark plug is arranged on one side of the injection panel of the rectangular model engine or on the combustion chamber wall surface adjacent to the injection panel in the transverse direction. The application utilizes the high-energy spark plug device, forms pressure oscillation disturbance in the combustion chamber by igniting at reasonable ignition positions on the wall surface of the model rocket engine and by igniting multiple times with different frequencies, evaluates the combustion stability of the model engine, and further proposes a method for inhibiting combustion instability.

Description

TECHNICAL FIELD

[0001] The present application relates to a rocket engine combustion characteristic analysis device, in particular to a combustion stability evaluation device based on a high-energy spark plug. BACKGROUND

[0002] The combustion chamber of a rocket engine is a compact confined space, which needs to organize the combustion of propellant and complete the conversion of chemical energy to kinetic energy, accompanied by extremely high heat release, and the lower acoustic damping of the combustion chamber, thus it is particularly prone to induce combustion instability. Due to the extremely high power of the rocket engine, only a small part of the total heat release is needed to be transferred to the acoustic field to obtain a larger pressure amplitude. Rayleigh criterion is a widely accepted basic theory in the field of combustion instability. Rayleigh proposed in 1878 that for an acoustically oscillating gas, if heat is added to the gas when it is most dense and heat is extracted from the gas when it is most sparse, the acoustic oscillation will be amplified, otherwise, the acoustic oscillation will be attenuated. In fact, Rayleigh criterion describes the energy transfer process from combustion to acoustic field in the process of unstable combustion: the acoustic pressure oscillation and the combustion oscillation are synchronized in space and time, i.e. the local combustion heat release provides energy to the local acoustic pressure oscillation in phase, and the unstable combustion is excited and maintained.

[0003] The mechanism of unstable combustion in a confined space, as shown in Figure 1 Thermoacoustic instability is a complex coupling process between acoustics-flow-combustion in the combustion chamber. Since there is a turbulent flame, perturbation exists. When the flame oscillation and the cavity acoustics interact complexly, high-frequency unstable combustion can be spontaneously generated. The combustion heat release fluctuation is the source of acoustic pressure oscillation, which will induce local pressure disturbance. When this disturbance propagates to the surrounding, some disturbances are reflected back to the flame after being injected into the wall, and at the same time, some disturbances will induce complex interaction between the flames. These reflected waves will in turn generate acoustic pressure and velocity fluctuations near the injection panel, thereby changing the mass flow of the propellant inflow and further causing local disturbance of the heat release rate. If these acoustic pressure disturbances change the combustion rate at the right phase, the combustion instability in the reaction zone will be enhanced, and the flame oscillation will be amplified. Further, this will lead to greater local acoustic pressure oscillation of the heat release rate oscillation, and the whole process forms a positive feedback process, in which energy is continuously transferred from the combustion process to the pressure oscillation of a certain acoustic mode, thereby driving the instability to grow. The acoustic pressure amplitude will increase to a certain extent until it is balanced with the dissipation of the surrounding flow field. Finally, the pressure oscillation shows a limit cycle state of equal amplitude oscillation.

[0004] The traditional method of evaluating the stability of engine combustion is mainly to set a disturbance device, including an explosive bomb and a pulse gun. Both belong to explosive disturbance devices, which ignite a pre-set explosive charge or a column of gunpowder to form a local pressure wave and heat release, thereby generating a large initial disturbance in the combustion chamber to analyze the stability of the combustion state in the combustion chamber. The explosive bomb is generally placed in the combustion chamber, and the pulse gun is placed on the wall. When evaluating the combustion stability, the disturbance device serves as an external excitation device, which can conveniently and quickly provide an excitation. However, both the explosive bomb and the pulse gun need to be pre-positioned with explosive gunpowder, and the charge equivalent needs to be calculated and experimented in advance. In addition, the explosive power needs to be adjusted appropriately according to the working condition adjustment and change of the combustion chamber. Therefore, it is extremely inconvenient for variable working conditions and multiple experiments. At the same time, the explosive bomb needs to be repositioned after each test, and the pulse gun also needs to be cleaned or replaced after multiple uses, which increases the operation steps of the experiment.

[0005] The MIC (Multiple Injector Combustor) model engine developed by the ONERA of the French aerospace laboratory has a rectangular cross section and uses LOX / CH4 as propellant. The acoustic forced excitation can be achieved by periodically switching the secondary nozzle through a gear. In a series of tests, the working conditions were systematically changed to determine the parameter range that leads to combustion sensitive to lateral excitation. In order to study the lateral unstable combustion under larger oscillation amplitudes, Méry et al. adjusted the acoustic excitation as shown in Figure 2 They designed a double-axial nozzle to produce large-amplitude lateral acoustic modulation by periodically alternating the blockage of the two exhaust nozzles of the combustion chamber. The test was carried out at a combustion chamber pressure of 5.5 MPa, and the peak-to-peak pressure amplitude of the lateral unstable combustion exceeded 20% of the average chamber pressure. High-speed photography found that under the action of the oscillating acoustic field, the liquid oxygen jet core length was greatly shortened, and large-scale lateral motion occurred in both jets, which would lead to periodic oscillation of the oxygen mass fraction in the chamber. This can be considered as the mechanism driving combustion instability.

[0006] The gear mechanism designed by the ONERA based on the MIC model engine produces large-amplitude lateral acoustic modulation by periodically alternating the blockage of the two exhaust nozzles of the combustion chamber, which can generate periodic disturbances in the combustion chamber. However, this method needs to adjust the size of the exhaust port or the speed of the gear at each variable working condition. In addition, under the high temperature and high pressure conditions of the combustion chamber, how to seal the gear and the outlet is also a difficult problem. Most importantly, this method periodically blocks and opens the engine nozzle, which directly changes the normal working process of the engine. Therefore, this method is only suitable for specific parameter research. SUMMARY

[0007] The technical problem solved by the present application is to provide a combustion stability evaluation device based on high-energy spark plug to solve the problems of the prior art.

[0008] To solve the above technical problems, the technical scheme adopted by the present application is:

[0009] The combustion stability evaluation device based on high-energy spark plug comprises a heat release disturbance device.

[0010] The heat release disturbance device comprises a longitudinal disturbance spark plug and a transverse disturbance spark plug.

[0011] The longitudinal disturbance spark plug is used to evaluate the longitudinal combustion stability of a model engine one.

[0012] The longitudinal disturbance spark plug is arranged in the front half of the combustion chamber of the model engine one in the longitudinal direction.

[0013] The transverse disturbance spark plug is used to evaluate the transverse combustion stability of a model engine two.

[0014] The transverse disturbance spark plug is arranged on the side of the injection panel of the model engine two or on the combustion chamber wall adjacent to the injection panel in the transverse direction.

[0015] Each longitudinal disturbance spark plug and each transverse disturbance spark plug is a high-energy spark plug.

[0016] When the longitudinal acoustic mode order of the model engine one is longitudinal first order, a = 1 or 2.

[0017] At this time, the longitudinal position of the injection panel of the model engine one is the first antinode position of the longitudinal first order acoustic mode, which is referred to as longitudinal first order first antinode.

[0018] The a longitudinal disturbance spark plugs can be arranged at any one or both of the longitudinal first-order first antinode and the longitudinal first-order first node.

[0019] When the longitudinal acoustic mode order of the model engine 1 to be studied is the second order, a = 1, 2 or 3.

[0020] At this time, the longitudinal position of the injection panel of the model engine 1 is the first antinode position of the second-order acoustic mode, referred to as the second-order first antinode, which is consistent with the first antinode of the first order; the longitudinal position of the L / 4 of the combustion chamber is the first node position of the second-order acoustic mode, referred to as the second-order first node; and the longitudinal position of the L / 2 of the combustion chamber is the second antinode position of the second-order acoustic mode, referred to as the second-order second antinode.

[0021] The a longitudinal disturbance spark plugs can be arranged at any one, two or three of the second-order first antinode, the second-order first node and the second-order second antinode.

[0022] When the transverse acoustic mode order of the model engine 2 to be studied is the first order, b = 1 or 2, and n ≥ 3.

[0023] At this time, the edge region of the injection panel of the model engine 2 is the first antinode position of the first-order acoustic mode, referred to as the first-order first antinode; and the center of the injection panel of the model engine 2 is the first node position of the first-order acoustic mode, referred to as the first-order first node.

[0024] When n is an odd number, the first nozzle is located at the first-order first antinode, the (n+1) / 2th nozzle is located at the first-order first node, and the b transverse disturbance spark plugs can correspond to the transverse positions of any one or both of the first nozzle and the (n+1) / 2th nozzle.

[0025] When n is an even number, the first nozzle is located at the first-order first antinode, the n / 2th and the n / 2+1th nozzles are symmetrically located on both sides of the center of the injection panel; and the b transverse disturbance spark plugs can correspond to the transverse positions of any one or both of the first nozzle and the n / 2th nozzle.

[0026] When the transverse acoustic mode order of the model engine 2 to be studied is the second order, b = 1, 2 or 3, and n ≥ 5.

[0027] At this time, the edge region of the injection panel of the model engine 2 is the first antinode position of the second-order acoustic mode, referred to as the second-order first antinode, which is consistent with the first antinode of the first order; the center of the injection panel of the model engine 2 is the second antinode position of the second-order acoustic mode, referred to as the second-order second antinode; and the position one quarter of the transverse length away from the edge region of the injection panel of the model engine 2 is the first node position of the second-order acoustic mode, referred to as the second-order first node.

[0028] When n is odd, the first nozzle is located at the transverse second-order first antinode, the (n+1) / 2th nozzle is located at the transverse second-order second antinode, and the ith nozzle is located at the transverse second-order first node; wherein, 1

[0029] The b transverse disturbance spark plugs can correspond to the transverse positions of any one, two or three of the first nozzle, the ith nozzle and the (n+1) / 2th nozzle.

[0030] When n is even, the first nozzle is located at the transverse first-order first antinode, the n / 2th and the n / 2+1th nozzles are symmetrically located on both sides of the center of the injection panel, and the jth nozzle is located at the transverse second-order first node; wherein, 1

[0031] The b transverse disturbance spark plugs can correspond to the transverse positions of any one, two or three of the first nozzle, the jth nozzle and the n / 2th nozzle.

[0032] When the longitudinal acoustic modal order of the model engine to be studied is the first longitudinal order, a=2; one longitudinal disturbance spark plug is arranged at the first longitudinal first antinode and the first longitudinal first node, respectively, so as to study the influence of heat release disturbance on the combustion state at the two different longitudinal positions of the antinode and the node.

[0033] When the longitudinal acoustic modal order of the model engine to be studied is the second longitudinal order, a=3; one longitudinal disturbance spark plug is arranged at the first longitudinal second antinode, the first longitudinal first node and the second longitudinal first node, respectively.

[0034] The longitudinal disturbance spark plug arranged at the first longitudinal second antinode can be used to simultaneously excite the first longitudinal acoustic modal and the second longitudinal acoustic modal.

[0035] The longitudinal disturbance spark plugs arranged at the first longitudinal first node and the second longitudinal first node can be used to study the relationship between the longitudinal combustion instability mode and the acoustic modal.

[0036] When the transverse acoustic modal order of the model engine to be studied is the first transverse order, b=2, and n is an odd number not less than 3; the two transverse disturbance spark plugs correspond to the transverse positions of the first nozzle and the (n+1) / 2th nozzle, respectively, and can be used to study the influence of heat release disturbance on the combustion state at the two different transverse positions of the antinode and the node.

[0037] When the transverse acoustic modal order of the model engine to be studied is the second transverse order, b=3, and n is an odd number not less than 5; the three transverse disturbance spark plugs correspond to the transverse positions of the first nozzle, the ith nozzle and the (n+1) / 2th nozzle, respectively;

[0038] The transverse disturbance spark plug arranged at the transverse second-order first wave crest can be used to simultaneously excite the transverse first-order acoustic mode and the transverse second-order acoustic mode;

[0039] The longitudinal disturbance spark plug arranged at the transverse second-order first node and the transverse second-order second wave crest can be used to study the relationship between the transverse combustion instability mode and the acoustic mode.

[0040] n=5, the first nozzle and the fifth nozzle are arranged at the edge regions of the injection panel of the model engine two respectively; the second nozzle and the fourth nozzle are arranged at the positions with a quarter of the transverse length away from the edge regions of the injection panel of the model engine two respectively, and the third nozzle panel is arranged at the center of the injection panel of the model engine two.

[0041] Supposing that the main frequency of the high-frequency unstable combustion of the model engine one or the model engine two is F, and the ignition frequency of the longitudinal disturbance spark plug or the transverse disturbance spark plug is f, then F=kf; wherein k is a natural number, so that the two have a coupling or weak coupling relationship.

[0042] The ignition frequency of the longitudinal disturbance spark plug or the transverse disturbance spark plug is a series of different frequencies, and any one frequency f m in the series satisfies F=kf m ; so that the influence of low-frequency disturbance on the combustion stability of the engine under continuous ignition disturbance of the series of different frequencies can be studied.

[0043] The present application has the following beneficial effects:

[0044] 1. The present application uses a high-energy spark plug device, forms pressure and heat release disturbance in the combustion chamber by reasonably designing the ignition position on the wall surface of the model rocket engine and using multiple ignition with different frequencies, and thus evaluates the combustion stability of the model engine.

[0045] 2. The high-energy spark plug used in the present application generates a high-energy spark after being electrified, forms a local fire core, ignites the combustible mixture gathered in the combustion chamber, generates local heat release and pressure wave, and achieves the same effect as an explosive bomb, which is convenient to control and does not cause great influence on the working process of the engine. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 A mechanism diagram of unstable combustion in a limited space in the prior art is shown.

[0047] Figure 2 A mechanism diagram of combustion instability driven by a double-axial nozzle in the prior art is shown.

[0048] Figure 3 A schematic diagram of the setting position of the spark plug in the longitudinal combustion instability disturbance in the present application is shown.

[0049] Figure 4 A schematic diagram showing the setting position of the spark plug in the present application when transverse combustion instability disturbance occurs.

[0050] Figure 5 A sectional view of a model engine one provided with longitudinal disturbance spark plugs in the present application is shown.

[0051] Figure 6 A sectional view of a model engine two provided with transverse disturbance spark plugs in the present application is shown.

[0052] Among them:

[0053] 10. Injection panel; 20. Combustion chamber; 21. Quartz observation window; 30. Injection pipe; 40. Gear; 50. Combustion gas; 60. Longitudinal disturbance spark plug; 70. Transverse disturbance spark plug. DETAILED DESCRIPTION

[0054] The present application will be further described in detail below in conjunction with the accompanying drawings and specific preferred embodiments.

[0055] In the description of the present application, it should be understood that the terms "left side", "right side", "upper part", "lower part" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and "first", "second" and the like do not represent the importance of the parts, so it cannot be understood as a limitation on the present application. The specific dimensions used in the present embodiment are only for the purpose of illustrating the technical scheme and do not limit the protection scope of the present application.

[0056] As Figures 3 to 6 shown, a combustion stability evaluation device based on high-energy spark plug, comprising a heat release disturbance device.

[0057] The heat release disturbance device comprises a longitudinal disturbance spark plug 60 and a transverse disturbance spark plug 70; wherein a≥1; b≥1.

[0058] Each longitudinal disturbance spark plug and each transverse disturbance spark plug is a high-energy spark plug. The high-energy spark plug in the present embodiment is preferably an ignition voltage of not less than 1.8 ten thousand volts.

[0059] I. Longitudinal unstable combustion evaluation

[0060] The a longitudinal disturbance spark plugs are used to evaluate the longitudinal combustion stability of the model engine one; the model engine one is a circular model engine or a rectangular model engine. In the present embodiment, the model engine one is a single nozzle circular model engine as Figure 5 shown, and the length of the combustion chamber of the model engine one is L.

[0061] The large length-diameter ratio of the single-nozzle circular model engine is beneficial to promote the coupling of acoustic mode and pressure and heat release oscillation, and is beneficial to excite longitudinal combustion instability. Considering that the energy required to be maintained will also increase dramatically with the increase of combustion instability mode, therefore, the present scheme only studies the first two orders of combustion instability mode, and considering that the combustible mixture in the combustion chamber is mainly concentrated in the first half of the combustion chamber, therefore, the spark plug position is mainly set in the first half of the combustion chamber.

[0062] a longitudinal disturbance spark plugs are arranged in the first half of the combustion chamber of the model engine one along the longitudinal direction; the longitudinal positions of the a longitudinal disturbance spark plugs are determined according to the longitudinal acoustic mode order of the model engine one to be studied.

[0063] A, the setting position of the longitudinal disturbance spark plug in the first longitudinal order

[0064] When the longitudinal acoustic mode order of the model engine one to be studied is the first longitudinal order, a = 1 or 2.

[0065] As shown in Figure 3 , the longitudinal position of the injection panel of the model engine one is the first antinode position of the first longitudinal acoustic mode, simply referred to as the first longitudinal first antinode; the middle part of the combustion chamber at the longitudinal position L / 2 is the first node position of the first longitudinal acoustic mode, simply referred to as the first longitudinal first node.

[0066] The a longitudinal disturbance spark plugs can be arranged at any one or both of the first longitudinal first antinode and the first longitudinal first node.

[0067] In the present embodiment, it is preferred that a = 2; at this time, one longitudinal disturbance spark plug is arranged at each of the first longitudinal first antinode and the first longitudinal first node, thereby being able to be used to study the influence of heat release disturbance on the combustion state at two different longitudinal positions of the antinode and the node.

[0068] B, the setting position of the longitudinal disturbance spark plug in the second longitudinal order

[0069] When the longitudinal acoustic mode order of the model engine one to be studied is the second longitudinal order, a = 1, 2 or 3.

[0070] As shown in Figure 3 , the longitudinal position of the injection panel of the model engine one is the first antinode position of the second longitudinal acoustic mode, simply referred to as the second longitudinal first antinode, which is consistent with the first longitudinal first antinode; the longitudinal position L / 4 of the combustion chamber is the first node position of the second longitudinal acoustic mode, simply referred to as the second longitudinal first node; the longitudinal position L / 2 of the combustion chamber is the second antinode position of the second longitudinal acoustic mode, simply referred to as the second longitudinal second antinode.

[0071] a longitudinal perturbation spark plug can be arranged at any one, two or three of the longitudinal second-order first anti-node, the longitudinal second-order first node and the longitudinal second-order second anti-node.

[0072] In the present embodiment, a = 3 is preferred; one longitudinal perturbation spark plug is arranged at each of the longitudinal second-order first anti-node, the longitudinal second-order first node and the longitudinal second-order second anti-node.

[0073] The longitudinal perturbation spark plug arranged at the longitudinal second-order first anti-node can be used to simultaneously excite the longitudinal first-order acoustic mode and the longitudinal second-order acoustic mode.

[0074] Comparison Figure 3 From the above two figures, the difference between the first-order and second-order acoustic modes at specific positions can be found: the anti-node position of the second-order acoustic mode is observed at a quarter of the length of the combustion chamber from the injection panel, and the amplitude in the first-order acoustic mode is close to the anti-node position; the anti-node position of the second-order acoustic mode is at the center of the combustion chamber, while it is at the node in the first-order acoustic mode, so arranging longitudinal perturbation spark plugs at the longitudinal second-order first node and the longitudinal second-order second anti-node can be used to study the relationship between the longitudinal combustion instability mode and the acoustic mode.

[0075] C, Ignition frequency of the longitudinal perturbation spark plug

[0076] Suppose that the main frequency of the high-frequency unstable combustion of the model engine is F, and the ignition frequency of the longitudinal perturbation spark plug is f, then F = kf; where k is a natural number, so that the two have a coupling or weak coupling relationship.

[0077] The ignition frequency of the longitudinal perturbation spark plug can also be a series of different frequencies, and any one frequency f m in the series satisfies F = kf m ; so as to study the influence of low-frequency perturbation under continuous ignition perturbation of a series of different frequencies on the combustion stability of the engine.

[0078] II. Evaluation of transverse unstable combustion

[0079] b transverse perturbation spark plugs are used to evaluate the transverse combustion stability of the model engine two; in the present embodiment, the model engine two is preferably a rectangular model engine as shown in Figure 6 ; the injection panel of the model engine two is provided with n injectors arranged in a row along the transverse direction.

[0080] The mechanism of generating transverse unstable combustion in the rectangular engine is that the combustion chamber pressure enters the injector and hinders the flow of propellant, thereby causing a propellant mass disturbance and further triggering a heat release oscillation, and the heat release oscillation and the pressure synchronous oscillation form a positive feedback closed loop of thermal-acoustic coupling to maintain the transverse unstable combustion.

[0081] b transverse disturbance spark plugs are arranged on the side of the injection panel or on the combustion chamber wall adjacent to the injection panel of the model engine two in the transverse direction; wherein b < n; the transverse positions of the b transverse disturbance spark plugs are determined according to the longitudinal acoustic mode order of the model engine two to be studied, and correspond to the transverse positions of the b injectors.

[0082] A, the arrangement position of the transverse disturbance spark plug in the transverse first order

[0083] When the longitudinal acoustic mode order of the model engine two to be studied is the transverse first order, b = 1 or 2, and n ≥ 3.

[0084] As shown in Figure 4 , the edge area of the injection panel of the model engine two is the first antinode position of the transverse first order acoustic mode, referred to as the transverse first order first antinode; the center of the injection panel of the model engine two is the first node position of the transverse first order acoustic mode, referred to as the transverse first order first node.

[0085] When n is an odd number, the first injector is located at the transverse first order first antinode, and the (n+1) / 2 injector is located at the transverse first order first node; the b transverse disturbance spark plugs can correspond to the transverse positions of any one or both of the first injector and the (n+1) / 2 injector.

[0086] When n is an even number, the first injector is located at the transverse first order first antinode, and the n / 2 and n / 2+1 injectors are symmetrically located on both sides of the center of the injection panel; the b transverse disturbance spark plugs can correspond to the transverse positions of any one or both of the first injector and the n / 2 injector.

[0087] In this embodiment, it is preferred that b = 2, n = 5, the first injector and the fifth injector are arranged adjacent to the edge area of the injection panel of the model engine two respectively; the second injector and the fourth injector are arranged at a distance of one quarter of the transverse length from the edge area of the injection panel of the corresponding model engine two, and the third injector panel is arranged at the center of the injection panel of the model engine two.

[0088] The two transverse disturbance spark plugs correspond to the transverse positions of the first injector and the (n+1) / 2 (preferably third) injector respectively, and can be used to study the influence of heat release disturbance at two different transverse positions of the antinode and the node on the combustion state.

[0089] B, the arrangement position of the transverse disturbance spark plug in the transverse second order

[0090] When the longitudinal acoustic mode order of the model engine two to be studied is the transverse second order, b = 1, 2 or 3, and n ≥ 5.

[0091] As shown in Figure 4As shown, the edge region of the injection panel of the model engine two is the first antinode position of the transverse second-order acoustic mode, referred to as the transverse second-order first antinode, which is consistent with the transverse first-order first antinode; the center of the injection panel of the model engine two is the second antinode position of the transverse second-order acoustic mode, referred to as the transverse second-order second antinode; and the position at a quarter of the transverse length from the edge region of the injection panel of the model engine two is the first node position of the transverse second-order acoustic mode, referred to as the transverse second-order first node.

[0092] When n is odd, the first nozzle is located at the transverse second-order first antinode, the (n+1) / 2th nozzle is located at the transverse second-order second antinode, and the ith nozzle is located at the transverse second-order first node; wherein 1

[0093] The b transverse disturbance spark plugs can correspond to the transverse positions of any one, two or three of the first nozzle, the ith nozzle and the (n+1) / 2th nozzle.

[0094] When n is even, the first nozzle is located at the transverse first-order first antinode, the n / 2th and the n / 2+1th nozzles are symmetrically located on both sides of the center of the injection panel, and the jth nozzle is located at the transverse second-order first node; wherein 1

[0095] The b transverse disturbance spark plugs can correspond to the transverse positions of any one, two or three of the first nozzle, the jth nozzle and the n / 2th nozzle.

[0096] In the present embodiment, it is preferred that b=3 and n=5, and the arrangement of the five nozzles is preferably the same as that of the transverse first-order. At this time, the three transverse disturbance spark plugs correspond to the transverse positions of the first nozzle, the ith nozzle (i.e., the second nozzle) and the (n+1) / 2th nozzle (i.e., the third nozzle), respectively.

[0097] The transverse disturbance spark plug arranged at the transverse second-order first antinode can be used to simultaneously excite the transverse first-order acoustic mode and the transverse second-order acoustic mode.

[0098] From Figure 4It can be seen that, whether it is a first-order or a second-order transverse acoustic mode, the edge region of the injection panel is a pressure wave antinode, and the difference is that the center position is a node of the first-order transverse acoustic mode, an antinode of the second-order transverse acoustic mode, and a node of the second-order transverse acoustic mode is located at a quarter of the transverse length from the edge. Therefore, in order to better align the spark plug excitation position with the nozzle and achieve the maximum disturbance effect, the five nozzles are not arranged at equal intervals. The center nozzle is at the center position, and the two nozzles on the left and right are located at a quarter of the transverse length from the edge and close to the edge (a certain distance is left from the edge to ensure a certain atomization effect, and the specific distance needs to be referred to the atomization characteristics of the nozzle). Similar to the longitudinal combustion instability disturbance scheme, high-energy spark plug probes are arranged on the wall surface of the nozzles at the antinode and node positions of the first and second orders, and in particular, longitudinal disturbance spark plugs are arranged at the first node of the second-order transverse mode and the second antinode of the second-order transverse mode, which can be used to study the relationship between the transverse combustion instability mode and the acoustic mode.

[0099] C, ignition frequency of the transverse disturbance spark plug

[0100] In terms of frequency design, since the maximum frequency of the high-energy spark plug currently purchased is low, it is difficult to form coupling with the high-frequency combustion instability main mode, and the ignition delay time and the high-energy spark plug charging time also need to be considered. Therefore, perfect frequency coupling is difficult to achieve. However, by controlling the ignition frequency to maintain a multiple relationship with the high-frequency combustion instability main frequency, a certain degree of weak coupling relationship can also be formed. Assuming that the second high-frequency instability combustion main frequency of the model engine is F, and the ignition frequency of the transverse disturbance spark plug is f, then F=kf; where k is a natural number, so that the two have a coupling or weak coupling relationship.

[0101] In addition, the ignition frequency of the transverse disturbance spark plug can also be a series of different frequencies, and any frequency f m in the series satisfies F=kf m ; so as to study the influence of low-frequency disturbance under continuous ignition disturbance of a series of different frequencies on the combustion stability of the engine.

[0102] The high-energy spark plug described above will generate a high-energy spark after being energized, forming a local fire kernel, thereby igniting the combustible mixture gathered in the combustion chamber, producing local heat release and pressure waves, achieving the same effect as an explosive bomb, which is convenient to control and does not have a large impact on the engine working process. Therefore, the present application uses a high-energy spark plug device to evaluate the combustion stability of the model rocket engine by reasonably designing the ignition position on the wall surface of the model rocket engine and using multiple ignition at different frequencies to form pressure oscillation disturbance in the combustion chamber, thereby proposing a method for suppressing combustion instability.

[0103] In the process of ignition test of model engine, high-energy spark plug can realize ignition of model engine with methane-gaseous oxygen and kerosene-gaseous oxygen propellant combination, and the electric fire time is short and the ignition pressure peak is stable. In the actual control process, a series of continuous ignition frequencies can be set to study the influence of low-frequency disturbance on the stability of the engine.

[0104] The above describes the preferred embodiments of the present application in detail, but the present application is not limited to the specific details in the above-described embodiments, and various equivalent transformations of the technical solutions of the present application can be made within the technical concept of the present application, and these equivalent transformations all belong to the protection scope of the present application.

Claims

1. A combustion stability evaluation device based on a high-energy spark plug, characterized in that: including a heat-releasing disturbance device; The heat release disturbance device includes a longitudinal disturbance spark plug and b transverse disturbance spark plug; wherein a≥1; b≥1; a longitudinal disturbance spark plug is used to evaluate the longitudinal combustion stability of the model engine 1; the model engine 1 is a circular model engine or a rectangular model engine; a longitudinal disturbance spark plug is arranged longitudinally in the front half of the combustion chamber of the model engine 1; the longitudinal position of the a longitudinal disturbance spark plug is determined according to the longitudinal acoustic mode order of the model engine 1 to be studied; b lateral disturbance spark plugs are used to evaluate the lateral combustion stability of the model engine 2; the model engine 2 is a rectangular model engine; the injection panel of the model engine 2 is provided with n nozzles arranged in a row along the horizontal direction; b transverse disturbance spark plugs are arranged transversely on one side of the injection panel of the second model engine or on the combustion chamber wall adjacent to the injection panel; wherein b < n; the transverse positions of the b transverse disturbance spark plugs are determined according to the transverse acoustic mode order of the second model engine to be studied and correspond to the transverse positions of the b nozzles therein; Each longitudinal disturbance spark plug and each lateral disturbance spark plug are high energy spark plugs.

2. The combustion stability evaluation device based on a high-energy spark plug according to claim 1, characterized in that: Assume that the length of the combustion chamber is L. When the order of the longitudinal acoustic mode of the engine model to be studied is the first longitudinal order, a=1 or 2; At this time, the longitudinal position of the injection panel of the model engine 1 is the first antinode position of the longitudinal first-order acoustic mode, referred to as the longitudinal first-order first antinode; the longitudinal position L / 2 in the middle of the combustion chamber is the first node position of the longitudinal first-order acoustic mode, referred to as the longitudinal first-order first node; A longitudinal disturbance spark plug can be set at any one or both of the longitudinal first-order first antinode and the longitudinal first-order first node; When the order of the longitudinal acoustic mode of the engine to be studied is the second longitudinal order, a=1, 2 or 3; At this time, the longitudinal position of the injection panel of the model engine 1 is the first antinode of the longitudinal second-order acoustic mode, referred to as the longitudinal second-order first antinode, which is consistent with the longitudinal first-order first antinode; the longitudinal position of the combustion chamber at L / 4 is the first node of the longitudinal second-order acoustic mode, referred to as the longitudinal second-order first node; the longitudinal position of the combustion chamber at L / 2 is the second antinode of the longitudinal second-order acoustic mode, referred to as the longitudinal second-order second antinode; A longitudinal disturbance spark plug can be set at any one, two or three of the longitudinal second-order first antinode, the longitudinal second-order first node and the longitudinal second-order second antinode.

3. The combustion stability evaluation device based on a high-energy spark plug according to claim 2, characterized in that: When the second transverse acoustic mode order of the engine model to be studied is the first transverse order, b=1 or 2, n≥3; At this time, the edge of the injection panel of the model engine 2 is the first antinode position of the transverse first-order acoustic mode, referred to as the transverse first-order first antinode; the center of the injection panel of the model engine 2 is the first node position of the transverse first-order acoustic mode, referred to as the transverse first-order first node; When n is an odd number, the first nozzle is located at the first antinode of the first order in the transverse direction, and the (n+1) / 2nd nozzle is located at the first node of the first order in the transverse direction; the b transverse disturbance spark plugs can correspond to the transverse positions of any one or both of the first nozzle and the (n+1) / 2nd nozzle; When n is an even number, the first nozzle is located at the first antinode of the first order in the horizontal direction, and the n / 2nd and n / 2+1th nozzles are symmetrically located on both sides of the center of the injection panel; b lateral disturbance spark plugs can correspond to the lateral positions of any one or both of the first and n / 2nd nozzles; When the second transverse acoustic mode order of the engine model to be studied is transverse second order, b=1, 2 or 3, n≥5; At this time, the edge of the injection panel of the model engine 2 is the first antinode position of the transverse second-order acoustic mode, referred to as the transverse second-order first antinode, which is consistent with the transverse first-order first antinode; the center of the injection panel of the model engine 2 is the second antinode position of the transverse second-order acoustic mode, referred to as the transverse second-order second antinode; the position at one-quarter of the transverse length of the injection panel edge of the model engine 2 is the first node position of the transverse second-order acoustic mode, referred to as the transverse second-order first node; When n is an odd number, the first nozzle is located at the first antinode of the second-order transverse wave, the (n+1) / 2th nozzle is located at the second antinode of the second-order transverse wave, and the i-th nozzle is located at the first node of the second-order transverse wave; where 1<i<(n+1) / 2; b lateral disturbance spark plugs can correspond to any one, two or three lateral positions among the 1st nozzle, the i-th nozzle and the (n+1) / 2-th nozzle; When n is an even number, the first nozzle is located at the first antinode of the first order in the transverse direction, the n / 2nd and n / 2+1th nozzles are symmetrically located on both sides of the center of the injection panel, and the jth nozzle is located at the first node of the second order in the transverse direction; where 1<j<n / 2; The b lateral disturbance spark plugs can correspond to any one, two or three lateral positions of the 1st nozzle, the jth nozzle and the n / 2th nozzle.

4. The combustion stability evaluation device based on a high-energy spark plug according to claim 3, characterized in that: When the order of the longitudinal acoustic mode of the model engine to be studied is the first longitudinal order, a=2; a longitudinal disturbance spark plug is set at the first antinode and the first node of the first longitudinal order, which can be used to study the influence of heat release disturbance on the combustion state at two different longitudinal positions of the antinode and the node.

5. The combustion stability evaluation device based on a high-energy spark plug according to claim 4, characterized in that: When the order of the longitudinal acoustic mode of the model engine to be studied is the longitudinal second order, a=3; a longitudinal disturbance spark plug is set at the first antinode of the longitudinal second order, the first node of the longitudinal second order, and the second antinode of the longitudinal second order; A longitudinal disturbance spark plug disposed at the first antinode of the longitudinal second order can be used to simultaneously excite the longitudinal first order acoustic mode and the longitudinal second order acoustic mode; The longitudinal disturbance spark plugs set at the first node and second antinode of the longitudinal second order can be used to study the relationship between the longitudinal combustion instability mode and the acoustic mode.

6. The combustion stability evaluation device based on a high-energy spark plug according to claim 3, characterized in that: When the second transverse acoustic mode order of the model engine to be studied is the first transverse order, b=2, and n is an odd number not less than 3; the two transverse disturbance spark plugs correspond to the transverse positions of the first nozzle and the (n+1) / 2 nozzle, respectively, and can be used to study the influence of heat release disturbance on the combustion state at two different transverse positions, the antinode and the node.

7. The combustion stability evaluation device based on a high-energy spark plug according to claim 6, characterized in that: When the second transverse acoustic mode order of the engine model to be studied is transverse second order, b = 3, n is an odd number not less than 5; the three transverse disturbance spark plugs correspond to the transverse positions of the 1st nozzle, the i-th nozzle, and the (n+1) / 2nd nozzle respectively; A transverse disturbance spark plug disposed at the first antinode of the transverse second order wave can be used to simultaneously excite the transverse first order acoustic mode and the transverse second order acoustic mode; The longitudinal disturbance spark plugs set at the first node and second antinode of the second order transverse wave can be used to study the relationship between the transverse combustion instability mode and the acoustic mode.

8. The combustion stability evaluation device based on a high-energy spark plug according to claim 6 or 7, characterized in that: n=5, the first nozzle and the fifth nozzle are respectively arranged at the edge of the injection panel adjacent to the model engine 2; the second nozzle and the fourth nozzle are respectively arranged at a quarter of the horizontal length of the injection panel edge corresponding to the model engine 2, and the third nozzle panel is arranged at the center of the injection panel of the model engine 2.

9. The combustion stability evaluation device based on a high-energy spark plug according to claim 1, characterized in that: Assuming that the main frequency of high-frequency unstable combustion of model engine 1 or model engine 2 is F, and the ignition frequency of the longitudinal disturbance spark plug or the transverse disturbance spark plug is f, then F=kf; where k is a natural number, so that the two can have a coupled or weakly coupled relationship.

10. The combustion stability evaluation device based on a high-energy spark plug according to claim 9, characterized in that: The ignition frequency of the longitudinal disturbance spark plug or the transverse disturbance spark plug is a series of different frequencies, and any frequency f in the series m All satisfy F=kf m ; This allows the study of the effects of low-frequency disturbances on engine combustion stability under a series of continuous ignition disturbances of different frequencies.

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