Method for initiating fuel injection for stable fuel injection in accelerated liquid fuel rotating detonation

Abstract

This invention discloses a fuel injection method for accelerating the stabilization of liquid fuel rotational detonation initiation, relating to the design of ignition schemes for rotational detonation ramjet engines. In the first stage of fuel pipeline pressure build-up and the second stage of the development of rotational detonation after initiation, the fuel injection method is limited by short-term fuel flow rate regulation to obtain the optimal fuel-air mixture state suitable for rotational detonation initiation. The short-term fuel flow rate regulation is achieved through short-term fuel injection bypass or short-term fuel pressure regulation. This invention, without significantly altering the original supply system, utilizes short-term fuel regulation to control the fuel injection pressure during the initiation stage, achieving a better combustible gas mixing effect and distribution, improving initiation reliability, and shortening the evolution time for the development of a stable rotational detonation flow field after initiation.

Description

Technical Field

[0001] This invention relates to the field of ignition scheme design for rotary detonation ramjet engines. More specifically, this invention relates to a fuel injection method for accelerating and stabilizing the rotary detonation initiation of liquid fuel. Background Technology

[0002] Rotating detonation is a novel combustion heat release method with advantages such as rapid heat release rate, high theoretical cycle efficiency, and continuous stable operation after a single ignition. Rotating detonation can propagate stably over a wide range of incoming flow velocities and can be applied to rocket engines, turbine engines, ramjet engines, and combined-fuel engines. Because the detonation wave propagates continuously in a circular rotational direction, rotating detonation can operate stably after a successful initiation, but this also places higher demands on the rapid and reliable initiation of rotating detonation.

[0003] For propulsion systems based on rotating detonation combustion, the process from the engine / aircraft control system issuing the engine ignition command to achieving stable thrust mainly involves three stages: propellant pipeline pressurization and ignition, the development of rotating detonation after detonation, and stable operation under rotating detonation. Therefore, the delay time from detonation to the formation of a stable combustion flow field is the sum of the first and second stages. The first stage primarily involves the fuel pipeline pressurization time. For liquid fuels, the flow rate is generally proportional to the 0.5 power of the supply pressure; increasing the supply pressure is a direct way to shorten the fuel chamber pressurization time (corresponding to the first stage). For the second stage, experimental and numerical studies show that after rotating detonation initiation, it undergoes stages such as deflagration and the transition from deflagration to detonation. The ignition location, mixing effect, and equivalence ratio collectively determine the flow field development and the establishment process of the rotating detonation wave after initiation.

[0004] For a given operating condition (propellant flow rate, supply pressure) and a selected detonation scheme (detonation location, intensity), the propellant (fuel) injection strategy determines the pressure build-up process in the propellant pipeline and the fuel chamber, directly affecting the fuel mixing process and effect entering the combustion chamber, and is a key factor influencing the rapid formation of rotating detonation.

[0005] To date, no feasible approach has been proposed for the rapid and reliable initiation of rotating detonation engines, addressing the propellant (fuel) supply scheme that significantly impacts the first stage of fuel line pressurization and the development of the second stage of rotating detonation after initiation. This approach aims to shorten the fuel line pressurization time, improve the fuel mixing effect during the initiation stage, accelerate the initiation and stabilization of liquid fuel rotating detonation, and achieve rapid and reliable initiation. Summary of the Invention

[0006] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0007] To achieve these objectives and other advantages of the present invention, a fuel injection method for accelerating the stabilization of rotating detonation in liquid fuel is provided. In the first stage of fuel pipeline pressure building and the second stage of developing rotating detonation after detonation, the fuel injection method is limited by short-term fuel flow rate regulation to shorten the fuel pipeline pressure building time and obtain the oil-gas mixture state that forms the rotating detonation stable flow field as quickly as possible after detonation. The short-term fuel flow regulation is achieved through short-term fuel injection bypass or short-term fuel pressure regulation.

[0008] Preferably, for operating conditions with low supply flow and pressure, the supply flow can be increased by opening a short-term fuel injection bypass or a short-term pressurization control method to shorten the fuel pipeline pressure build-up time t1.

[0009] Preferably, the operating pressure p is lower than the shortest rotational detonation initiation evolution time t. 2min The corresponding optimal supply pressure p t2min Under test conditions, when using the short-term boost control method, the optimal short-term fuel supply pressure p opt Choose: p opt =p t2min ; When using a short-term fuel bypass for injection, the opening time of the fuel supply channel on the short-term fuel bypass should be consistent with the opening time of the fuel valve. Furthermore, the pipe size of the short-term fuel bypass should be selected to ensure that the total supply pressure after the short-term fuel bypass is opened is consistent with p. t2min Consistent.

[0010] Preferably, for operating conditions with high supply flow and pressure, the initial stage fuel flow and supply pressure can be reduced by opening the short-term fuel bypass venting channel or by short-term pressure reduction control, so as to shorten the evolution time t2 of the rotating detonation flow field after detonation.

[0011] Preferably, the operating pressure p is higher than the shortest rotational detonation initiation evolution time t. 2min The corresponding supply pressure p t2min Under test conditions, when using the short-term pressure reduction control method, the optimal short-term fuel supply pressure p opt Choose: p opt =p t2min After the fuel pipeline pressurization time t1 and the evolution time t2 of the rotating detonation flow field after detonation, the supply pressure will be restored to p.

[0012] Preferably, the supply pressure p is higher than p under operating conditions. t2minUnder the test conditions, when the method of opening the venting channel is adopted, the operating supply pressure p is kept constant, the opening time of the venting channel on the short-term fuel bypass is consistent with the opening time of the fuel valve, and after the fuel pipeline pressure build-up time t1 and the evolution time of the rotating detonation flow field after detonation t2, the venting valve is closed to restore the supply pressure to pressure p. When the venting channel is opened, a flow-limiting device on the venting channel is needed to ensure that the total supply pressure after venting is consistent with p. t2min Consistent.

[0013] The present invention has at least the following beneficial effects: Firstly, this invention utilizes short-time fuel regulation to control the fuel injection pressure during the detonation stage, thereby achieving a better combustible gas mixing effect and distribution, improving detonation reliability, and shortening the evolution time t2 for the formation of a stable rotating detonation flow field after detonation.

[0014] Secondly, this invention comprehensively considers the fuel pipeline pressure build-up time t1 and the evolution time t2 for the formation of a stable rotating detonation flow field after detonation within the operating range, thereby reducing the total time from valve actuation to stable operation of rotating detonation and improving the engine response capability, aircraft maneuverability and survivability under application conditions.

[0015] Third, the injection method used in this invention can prevent extreme situations that affect the operation of the aircraft, such as the long detonation development time under the traditional fuel supply strategy, which leads to the accumulation of a lot of fuel in the combustion chamber, rapid combustion after detonation, high combustion chamber pressure, pressure disturbance, and failure of the air intake to start, for operating conditions with a high equivalence ratio.

[0016] Fourth, the short-term fuel regulation of the present invention does not introduce significant changes to the original supply system.

[0017] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the fuel pipeline pressure build-up time t1 under different injection pressures in this invention; Figure 2 This is a schematic diagram showing the evolution time t2 of rotating detonation initiation under different injection pressures in this invention; Figure 3 The present invention provides a supply pressure p lower than p under operating conditions. t2min In the short-term control method, a schematic diagram of the supply pressure during the short-term boost control process is used; Figure 4 The present invention provides a supply pressure p lower than p under operating conditions. t2minA schematic diagram of the supply pressure during the short-term fuel bypass injection process is used in the short-term control method. Figure 5 The present invention provides a supply pressure p higher than p under operating conditions. t2min In the short-term control method, a schematic diagram of the supply pressure during the short-term pressure reduction control process is used; Figure 6 The present invention provides a supply pressure p higher than p under operating conditions. t2min The diagram illustrates the supply pressure during the short-term fuel bypass discharge process in the short-term control method. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0020] For a specific test scheme and under certain test conditions, the relationship between the fuel pipeline pressure build-up time t1, the volume V of the pipeline downstream of the valve and the fuel chamber, and the supply pressure p under test conditions is as follows: in, The mass flow rate when the fuel pipeline is supplied with pressure P.

[0021] Typically, a cavitation pipe is used to control the pipeline flow rate. The throat area of ​​the cavitation pipe is A, and the flow coefficient is C. d , ρ For fuel density, P cav Given the saturated vapor pressure at the corresponding temperature (much lower than the supply pressure), the pressure build-up time t1 in the fuel pipeline is: Figure 1 This diagram illustrates the variation of fuel pipeline pressurization time t1 with operating supply pressure p. t2min It is the supply pressure that most quickly develops into a stable rotating detonation flow field after detonation, t 1p This represents a pressure of p. t2min (The fuel pipeline pressure build-up time at that time). It should be noted that, through experiments, the fuel pipeline pressure build-up time t1 under different supply pressures p and the evolution time t2 for the formation of a stable rotating detonation flow field after initiation can also be obtained, and the influence law of supply pressure can be obtained, and the corresponding shortest rotating detonation initiation and evolution time t can be determined. 2min The corresponding supply pressure p t2min ,like Figure 2 As shown.

[0022] Therefore, this invention proposes a fuel injection strategy based on short-term fuel flow rate regulation. For lower supply flow rate and pressure conditions, short-term fuel injection bypass injection or short-term fuel pressure regulation shortens the pressure build-up time and improves fuel atomization during the initiation phase, significantly reducing the time required to form a stable rotating detonation combustion flow field. For higher supply flow rate and pressure conditions, methods such as short-term fuel venting channels reduce the initial fuel flow rate and supply pressure, obtaining an optimal fuel-air mixture state suitable for rotating detonation initiation, thus rapidly forming a stable rotating detonation flow field and reducing the time required to form a stable rotating detonation combustion flow field after initiation. Through this fuel injection strategy, the pipeline pressure build-up time and the development process after rotating detonation initiation are reduced, improving the rapid and reliable operation and maneuverability of aircraft based on rotating detonation propulsion systems.

[0023] Based on this, it can be seen that the fuel injection strategy based on short-time fuel flow rate regulation proposed in this invention is a fuel injection method that accelerates the initiation and flow field stabilization of liquid fuel rotational detonation. It can shorten the pressure build-up time of the fuel pipeline, improve the fuel mixing effect during the detonation stage, improve the reliability of rotational detonation initiation, and accelerate the realization of stable operation of rotational detonation.

[0024] Example 1: For operating conditions, the supply pressure p is lower than p t2min The test conditions, such as Figures 3-4 As shown, the fuel supply flow rate is increased by briefly opening the fuel bypass or increasing the supply pressure, thus shortening the fuel pipeline pressure build-up time t1. When using the short-term pressure boosting method, the optimal short-term fuel supply pressure p... opt Choose: p opt =p t2min When using short-time fuel bypass injection, the valve opening time should be consistent with the fuel valve opening time, and the bypass pipeline size should be selected to ensure that the total supply pressure after the bypass is opened is consistent with p. t2min The results are consistent. Both methods restore the original supply pressure or close the bypass valve after ensuring stable rotating detonation is achieved (reference valve closing time: after 50 cycles of stable rotating detonation operation). After restoring the original supply pressure or closing the bypass valve, the fuel chamber pressure will decrease, but the rotating detonation can still operate stably. For the supply pressure p condition, the time from initiation to the formation of stable rotating detonation is t, which is shortened to t using the fuel control strategy of this invention. pt2min shorten time : In the above formula, This indicates a shortened fuel pipeline pressure build-up time. This indicates the shortened rotational detonation initiation evolution time. t1 and t2 represent the fuel pipeline pressure build-up time at pressure p and the evolution time for the formation of a stable rotational detonation flow field after initiation, respectively.1,p and t 2min These represent pressures p. t2min The time for fuel pipeline pressurization and the evolution time for the formation of a stable rotating detonation flow field after detonation. Example 2: For the operating condition supply pressure p is higher than p t2min The test conditions, such as Figures 5-6 As shown, methods such as reducing pipeline supply pressure or short-term fuel bypass venting can shorten the time required for initiation to form a stable rotating detonation. Typically, due to p t2min The supply pressure is relatively high, and its impact on the fuel pipeline pressure build-up time t1 is small, but its impact on the flow field development and formation time t2 after detonation is large. Therefore, the impact of the supply pressure on the fuel pipeline pressure build-up time t1 can be ignored.

[0025] like Figure 5 As shown, taking the method of reducing the pipeline supply pressure p as an example, p in the short-term fuel bypass opt Choose: p opt =p t2min After the fuel pressure build-up time t1 and the evolution time t2 of the rotating detonation initiation flow field, the supply pressure can be restored to p. Since a stable rotating detonation has already formed, after the fuel supply pressure is increased to the operating supply pressure p, the rotating detonation can reach stability in a relatively short time through flow field evolution. For this operating condition, after adopting the fuel control strategy of this invention, the time for initiation to form a stable rotating detonation is shortened to: For supply pressure p is higher than p t2min Under the test conditions, the pressure was reduced to p t2min The subsequent fuel pipeline pressurization time t1 and t 1,p The difference is not significant, therefore .like Figure 6 As shown, taking method 2 of short-term fuel bypass leakage as an example, the operating supply pressure p is kept constant, the opening time of the bypass valve is consistent with that of the fuel valve, and the flow limiting device must ensure that the supply pressure after leakage is the same as p. t2min Consistent. After the fuel pipeline pressure build-up time t1 and the evolution time of the rotating detonation flow field after detonation t2, closing the drain valve will restore the supply pressure to the operating supply pressure p. Similarly, the shortened time for the formation of stable rotating detonation after detonation is consistent with the results of Method 1.

[0026] The above solution is merely an illustration of a preferred example and is not limited thereto. When implementing this invention, appropriate substitutions and / or modifications can be made according to the user's needs.

[0027] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be readily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A fuel injection method for accelerating and stabilizing the rotary detonation initiation of liquid fuel, characterized in that, In the first stage of fuel pipeline pressurization and the second stage of developing rotating detonation after detonation, the fuel injection method is limited by short-term fuel flow regulation in order to shorten the fuel pipeline pressurization time and obtain the oil-gas mixture state that forms the rotating detonation stable flow field as quickly as possible after detonation. The short-term fuel flow regulation is achieved through short-term fuel injection bypass or short-term fuel pressure regulation.

2. The method of claim 1, wherein the fuel injection is accelerated to a speed of at least 100 m / s. 2 For operating conditions with low supply flow and pressure, the supply flow can be increased by opening a short-term fuel injection bypass or a short-term pressurization control method to shorten the fuel pipeline pressure build-up time t1.

3. The method of claim 2, wherein the fuel injection is accelerated to a speed of at least 100 m / s. When the supply pressure p is lower than the shortest rotational detonation initiation evolution time t, 2min The corresponding supply pressure p t2min Under test conditions, when using the short-term boost control method, the optimal short-term fuel supply pressure p opt Choose: p opt =p t2min ; When using a short-term fuel bypass for injection, the opening time of the fuel supply channel on the short-term fuel bypass should be consistent with the opening time of the fuel valve. Furthermore, the pipe size of the short-term fuel bypass should be selected to ensure that the total supply pressure after the short-term fuel bypass is opened is consistent with p. t2min Consistent.

4. The method of claim 1, wherein the fuel injection is accelerated to a speed of at least 100 m / s. For operating conditions with high supply flow and pressure, the initial fuel flow and supply pressure can be reduced by opening the short-term fuel bypass venting channel or by short-term pressure reduction control, so as to shorten the evolution time t2 of the rotating detonation flow field after detonation.

5. The method of claim 4, wherein the fuel injection is accelerated to a speed of at least 100 m / s. 5 When the supply pressure p is higher than the shortest rotational detonation initiation evolution time t, 2min The corresponding supply pressure p t2min Under test conditions, when using the short-term pressure reduction control method, the optimal short-term fuel supply pressure p opt Choose: p opt =p t2min After the fuel pipeline pressurization time t1 and the evolution time t2 of the rotating detonation flow field after detonation, the supply pressure will be restored to p.

6. The fuel injection method for accelerating and stabilizing the rotary detonation initiation of liquid fuel as described in claim 4, characterized in that, When the supply pressure p is higher than p under operating conditions t2min Under the test conditions, when the method of opening the venting channel is adopted, the operating supply pressure p is kept constant, the opening time of the venting channel on the short-term fuel bypass is consistent with the opening time of the fuel valve, and after the fuel pipeline pressure build-up time t1 and the evolution time of the rotating detonation flow field after detonation t2, the venting valve is closed to restore the supply pressure to pressure p. When the short-term discharge channel is opened, a flow-limiting device on the discharge channel is needed to ensure that the total supply pressure after discharge is equal to p. t2min Consistent.

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