Flow control device and method for pulse injection mixing enhancement

Abstract

The present invention discloses a flow control device and method for pulse injection mixing enhancement. The device includes an internal flow channel in the engine, an incoming flow control mechanism, and a fuel injection mechanism. The incoming flow control mechanism is located at the inlet of the internal flow channel in the engine and is used to fan the steady-state axial air inflow to form an unsteady, highly turbulent axial pulsating air inflow. The fuel injection mechanism is located on the inner wall of the internal flow channel in the engine and is used to sequentially inject fuel in intervals of pulses to form an unsteady, highly turbulent transverse pulsating fuel jet. The pulsation frequency of the axial pulsating air inflow and the transverse pulsating fuel jet are the same, and the pulsation phase difference is less than or equal to π / 2. The present invention is applied to the field of non-uniform fuel mixing and is used to achieve short-range, rapid, efficient and uniform mixing of reactants, improve the combustion efficiency, combustion intensity, and pressure gain of the combustion chamber, and thus realize an efficient supercharged combustion process with high-frequency self-sustaining engine and high specific impulse output.

Description

Technical Field

[0001] The present invention relates to the technical field of non-uniform fuel mixing, in particular to a flow control device and method for pulse injection mixing enhancement. Background Art

[0002] For non-premixed combustion processes, the degree of mixing uniformity of reactants within a confined length configuration significantly impacts combustion efficiency and intensity. In recent years, domestic and international researchers have conducted extensive research on the non-uniform mixing process of fuel under real lateral injection conditions on the inner wall of an engine, focusing on axial steady-state inflow conditions. The results show that under steady-state axial low-Mach number air flow, lateral steady-state injection of fuel on the inner wall of an engine with a confined axial length suffers from problems such as uneven fuel distribution (the fuel is mainly distributed near the wall, with very little in the central flow field) and poor reactant mixing. This results in incomplete combustion after ignition and limited combustion intensity, resulting in limited pressure gain and thrust performance far below expectations for supercharged combustion engines.

[0003] Traditional solutions to this problem fall into two main categories: 1. Increasing the engine's axial length, thereby achieving relatively good mixing of the reactants farther downstream from the engine's air intake. 2. Increasing the fuel injection pressure, thereby increasing the fuel's penetration depth and achieving relatively good mixing within a shorter axial length. However, both of these solutions significantly increase the engine's size and cost.

[0004] Therefore, it is urgent to develop a high-performance flow control method or device for efficient and uniform mixing of reactants over a short distance and quickly through a simple high-frequency intake valve and fuel pulse injection scheme. Summary of the Invention

[0005] In response to the above-mentioned deficiencies in the prior art, the present invention provides a flow control device and method for pulse injection mixing enhancement, which is mainly used to achieve efficient and uniform mixing of reactants in a short distance and fast manner, improve the combustion efficiency, combustion intensity and pressure gain of the combustion chamber, and thus realize an efficient supercharged combustion process with high-frequency self-sustaining and high specific impulse output of the engine.

[0006] To achieve the above-mentioned object, the present invention provides a flow control device for pulse injection mixing enhancement, comprising an engine internal flow channel, an incoming flow control mechanism and a fuel injection mechanism;

[0007] The inflow control mechanism is provided at the inlet of the engine inner flow passage, and is used to fan the steady-state axial air inflow, thereby forming an unsteady, highly turbulent axial pulsating air inflow in the engine inner flow passage;

[0008] The fuel injection mechanism is arranged on the inner wall of the engine inner flow channel, and is used for injecting the fuel in interval pulses in sequence, thereby forming a non-steady-state, highly turbulent transverse pulsating fuel jet in the engine inner flow channel;

[0009] The pulsation frequency of the axial pulsating air flow is the same as that of the transverse pulsating fuel jet, and a pulsation phase difference between the axial pulsating air flow and the transverse pulsating fuel jet is less than or equal to π / 2.

[0010] In one embodiment, the fuel injection mechanism includes a plurality of injection ports arranged circumferentially in the same cross-section in the flow channel within the engine.

[0011] In one embodiment, the axially pulsating air flow forms a normal shock wave in the engine inner flow passage that is pushed downstream, and the injection port is located downstream of where the normal shock wave is formed.

[0012] In one embodiment, the steady-state axial air flow is a low Mach number air flow of Ma0-Ma3.0.

[0013] In one embodiment, the fuel injection mechanism uses a non-steady-state injection method, including but not limited to square wave pulse injection, sinusoidal wave pulse injection, and sawtooth wave pulse injection.

[0014] In one embodiment, the incoming flow control mechanism includes a valve plate and a drive assembly;

[0015] One end of the valve plate is hinged to the inner wall surface at the inlet of the flow channel in the engine, and the other end is a suspended end;

[0016] The driving assembly is transmission-connected to the valve plate to drive the valve plate to rotate periodically, thereby periodically changing the flow area at the inlet of the flow channel in the engine to achieve fanning of the axial air flow.

[0017] In one embodiment, during the periodic rotation of the valve plate, the suspended end faces the downstream direction of the flow channel in the engine.

[0018] To achieve the above object, the present invention further provides a flow control method for pulse injection mixing enhancement, which uses the above flow control device to perform flow control;

[0019] The valve plate has a first state and a second state:

[0020] When the valve plate is in the first state, the valve plate is in contact with the inner wall surface of the flow channel in the engine;

[0021] When the valve plate is in the second state, the plane where the valve plate is located is perpendicular to the axial direction of the flow channel in the engine;

[0022] The process of the valve disc rotating from the first state to the second state is defined as a first rotation stage, and the process of the valve disc rotating from the second state to the first state is defined as a second rotation stage. The first rotation stage and the second rotation stage have the same duration and together constitute a pulsation cycle of the axial pulsating air flow. The initial state of the valve disc is the first state.

[0023] In the flow control method, after the flow passage in the engine starts to operate:

[0024] First, the driving assembly is started to drive the valve plate to rotate and keep the fuel injection mechanism closed;

[0025] When the valve plate rotates to zero to a quarter of a cycle, the fuel injection mechanism is opened.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects:

[0027] The present invention utilizes the resonance enhancement principle that periodic mass addition into a smooth tube can produce a resonance enhancement effect, thereby driving and enhancing the pulsation degree of the fluid in the flow channel and the mixing effect of the reactants. By arranging a flow control mechanism and a fuel injection mechanism on the flow channel inside the engine, an axial pulsating air flow and a transverse pulsating fuel jet are generated in the flow channel inside the engine, and the pulsation frequency of the axial pulsating air flow and the transverse pulsating fuel jet are kept the same, and the pulsation phase difference is less than or equal to π / 2, thereby effectively enhancing the mixing degree of air and fuel, realizing efficient and uniform mixing of reactants in a short distance and quickly, improving the combustion efficiency, combustion intensity and pressure gain of the combustion chamber, and thus improving the thrust performance of the supercharged combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0029] Figure 1 Schematic diagram of a flow control device for pulse jet mixing enhancement according to an embodiment of the present invention;

[0030] Figure 2 Schematic diagram of transverse pulse injection of circumferential wall fuel in an embodiment of the present invention;

[0031] Figure 3 Schematic diagram of a square wave pulse injection method of fuel in an embodiment of the present invention;

[0032] Figure 4 Schematic diagram of the degree of mixing along the steady-state air flow under the steady-state lateral fuel jet in an embodiment of the present invention;

[0033] Figure 5 Schematic diagram of the degree of mixing along the axial pulsating air flow and the transverse pulsating fuel jet in an embodiment of the present invention.

[0034] Reference numerals: flow channel in engine 1, flow control mechanism 2, fuel injection mechanism 3, steady-state axial air flow 4, axial pulsating air flow 5, transverse pulsating fuel jet 6, normal shock wave 7.

[0035] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0039] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; it can mean mechanical connection, electrical connection, physical connection, or wireless communication connection; it can mean direct connection or indirect connection through an intermediate medium; it can mean internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] like Figure 1 Shown is a pulse injection mixing enhancement flow control device disclosed in this embodiment (hereinafter referred to as "flow control device"), which mainly includes an engine internal flow channel 1, an incoming flow control mechanism 2 and a fuel injection mechanism 3.

[0042] The inlet flow control mechanism 2 is provided at the inlet of the engine inner flow passage 1 and is used to fan the steady-state axial air inlet flow 4, thereby forming an unsteady, highly turbulent axial pulsating air inlet flow 5 in the engine inner flow passage 1. The fuel injection mechanism 3 is provided on the inner wall surface of the engine inner flow passage 1 and is used to sequentially inject fuel in pulses at intervals, thereby forming an unsteady, highly turbulent transverse pulsating fuel jet 6 in the engine inner flow passage 1. The engine inner flow passage 1 has a rectangular or circular cross-section, etc., and the injection direction of the transverse pulsating fuel jet 6 includes but is not limited to being perpendicular to the inner wall surface. The pulsation frequency of the axial pulsating air inlet flow 5 and the transverse pulsating fuel jet 6 are the same, and the pulsation phase difference between the axial pulsating air inlet flow 5 and the transverse pulsating fuel jet 6 is less than or equal to π / 2. For example, when the pulsating pressure of the axial pulsating air inlet flow 5 reaches a peak, the pulsating pressure of the transverse pulsating fuel jet 6 is in an ascending stage or reaches a peak.

[0043] According to the resonance enhancement principle of the generalized Rayleigh criterion, periodic mass addition to a smooth tube can produce a resonance enhancement effect, driving and enhancing the pulsation of the fluid within the flow channel and the mixing effect of the reactants. Based on this, this embodiment utilizes the flow control mechanism 2 and the fuel injection mechanism 3 to form an axially pulsating air flow 5 and a transversely pulsating combustion jet 6 in the engine's internal flow channel 1. The pulsation frequency of the axially pulsating air flow 5 and the transversely pulsating fuel jet 6 is the same, ensuring that the flow system is in a resonant state, thereby amplifying the pulsation amplitude. The pulsation phase difference between the axially pulsating air flow 5 and the transversely pulsating fuel jet 6 is less than or equal to π / 2, resulting in the energy of the axially pulsating air flow 5 and the transversely pulsating fuel jet 6 being superimposed rather than canceled out, meeting the positive feedback condition of the Rayleigh criterion and further strengthening the resonance enhancement effect. Therefore, the flow control device in this embodiment can achieve efficient and uniform mixing of reactants over a short distance, improving combustion efficiency, combustion intensity, and pressure gain after ignition, thereby enhancing the thrust performance of the supercharged combustion engine.

[0044] In this embodiment, the inflow control mechanism 2 includes a valve disc and a drive assembly. One end of the valve disc is hinged to the inner wall surface at the entrance of the engine internal flow channel 1 via a pin, and the other end is a suspended end. The drive assembly (such as an electric motor or a pneumatic motor, etc.) is arranged outside the engine internal flow channel 1, and a portion of the pin can be extended out of the engine internal flow channel 1. The drive assembly and the pin are connected by a gear pair, so that the drive assembly can drive the valve disc to flap back and forth at a high frequency, thereby periodically changing the flow area at the entrance of the engine internal flow channel 1, that is, it can stir the steady-state axial air flow 4 into a non-steady-state, highly turbulent axial pulsating air flow 5, thereby achieving an enhanced mixing effect of the reactants.

[0045] In addition, during the high-frequency reciprocating flapping process, the valve disc can also form an unstable positive shock wave 7 in the strong turbulence flow field, which can be pushed downstream at any time, and the positive shock wave 7 can further enhance the mixing degree of the reactants.

[0046] In the specific implementation process, during the periodic reciprocating flapping of the valve plate, the suspended end faces the downstream direction of the flow channel 1 in the engine, so that the air can flow to the downstream better, ensuring that the fuel is in contact with enough air at the first time.

[0047] It is worth noting that in the specific application process, it is not limited to using the valve plate as the flow control mechanism 2. It is also possible to arrange a synthetic jet actuator or a synthetic dual jet actuator at the inlet of the flow channel 1 in the engine. The actuator can generate a transverse periodic jet, which also has the effect of disturbing the steady-state axial air flow 4 and generating an axial pulsating air flow 5.

[0048] In this embodiment, the fuel injection mechanism 3 includes a plurality of injection ports arranged circumferentially in the same cross section in the engine inner flow channel 1, and the injection ports are located downstream of the formation of the normal shock wave 7. For example, Figure 2 The figure shows an internal flow channel 1 of an engine with a circular cross section. In this case, the fuel injection mechanism 3 includes four injection ports, which are evenly distributed in a cross shape on the inner wall of the internal flow channel 1. The injection ports can be opened and closed synchronously, or can inject fuel in intervals according to a preset sequence.

[0049] In this embodiment, the injection method of the fuel injection mechanism 3 is as follows: Figure 3 The square wave pulse injection shown can also be used in unsteady injection methods such as sinusoidal or sawtooth pulse injection. Unsteady pulse injection can form a strong annular vortex with strong entrainment near the injection port, further significantly increasing the fuel penetration depth and mixing area.

[0050] The axial air flow 4 in this embodiment is preferably an axial low Mach number air flow of Ma0-Ma3.0, so as to achieve an optimal balance between the resonance enhancement effect, mixing efficiency, combustion stability and engineering feasibility.

[0051] This embodiment also discloses a flow control method for pulse injection mixing enhancement, which performs flow control by adopting the above-mentioned flow control device. Taking the inflow control mechanism 2 composed of the valve plate and the drive assembly as an example, the valve plate is defined as having a first state and a second state: when the valve plate is in the first state, the valve plate fits the inner wall surface of the engine internal flow channel 1, that is, at this time, the flow area at the inlet of the engine internal flow channel 1 is the largest; when the valve plate is in the second state, the plane where the valve plate is located is perpendicular to the axial direction of the engine internal flow channel 1, that is, at this time, the flow area at the inlet of the engine internal flow channel 1 is the smallest. At the same time, the process of the valve plate rotating from the first state to the second state is defined as the first rotation stage, and the process of the valve plate rotating from the second state to the first state is defined as the second rotation stage. The time of the first rotation stage is the same as that of the first rotation stage, and together they constitute a pulsation cycle of the axial pulsating air inflow 5. The initial state of the valve plate is the first state. In the flow control method, when the flow channel 1 in the engine starts to run, the drive component is first started to drive the valve plate to rotate and keep the fuel injection mechanism 3 closed; when the valve plate rotates to zero to a quarter of a cycle, the fuel injection mechanism 3 is opened, keeping the pulsation frequency of the axial pulsating air flow 5 and the lateral pulsating combustion jet 6 the same, and the pulsation phase difference is less than or equal to π / 2, thereby effectively enhancing the mixing degree of air and fuel.

[0052] The flow control device and method for pulse injection mixing enhancement in this embodiment will be further described below with reference to specific examples.

[0053] In this example, the pulse injection mixing enhancement flow control device of this embodiment is used in the numerical simulation of a certain fuel non-uniform mixing, wherein the inlet cross-sectional size of the flow channel 1 in the engine is 50mm×50mm, the outlet cross-sectional size is Φ40mm, and the total length is 600mm.

[0054] refer to Figure 4 Schematic diagram of the mixing degree along the steady-state air flow under the steady-state injection of the lateral fuel jet. Figure 5 Schematic diagram of the mixing degree of the axial pulsating air flow and the transverse pulsating fuel jet along the way. Figure 4 and Figure 5 It can be seen that compared with the steady-state injection of steady-state axial air flow, after adopting the flow control device of this embodiment, the reactants can be efficiently and uniformly mixed within a short distance.

[0055] The above description is only a preferred embodiment of the present invention and does not limit the scope of protection of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.

Claims

1. A flow control device for pulse injection mixing enhancement, characterized in that: It includes an engine internal flow channel, an incoming flow control mechanism and a fuel injection mechanism; The inflow control mechanism is provided at the inlet of the engine inner flow passage, and is used to fan the steady-state axial air inflow, thereby forming an unsteady, highly turbulent axial pulsating air inflow in the engine inner flow passage; The fuel injection mechanism is arranged on the inner wall of the engine inner flow channel, and is used for injecting the fuel in interval pulses in sequence, thereby forming a non-steady-state, highly turbulent transverse pulsating fuel jet in the engine inner flow channel; The pulsation frequency of the axial pulsating air flow is the same as that of the transverse pulsating fuel jet, and the pulsation phase difference between the axial pulsating air flow and the transverse pulsating fuel jet is less than or equal to π / 2. When the pulsating pressure of the axial pulsating air flow reaches a peak value, the pulsating pressure of the transverse pulsating fuel jet is in an ascending stage or reaches a peak value.

2. The pulse injection mixing enhanced flow control device according to claim 1, characterized in that: The fuel injection mechanism includes a plurality of injection ports arranged circumferentially in the same cross section in the engine inner flow channel.

3. The pulse injection mixing enhanced flow control device according to claim 2, characterized in that: The axial pulsating air flow forms a normal shock wave in the engine inner flow channel that is pushed downstream, and the injection port is located downstream of the formation of the normal shock wave.

4. The pulse jet mixing enhanced flow control device according to claim 1, 2 or 3, characterized in that: The steady-state axial air flow is a low Mach number air flow of Ma0 to Ma3.

0.

5. The pulse jet mixing enhanced flow control device according to claim 1, 2 or 3, characterized in that: The injection mode of the fuel injection mechanism is non-steady-state injection, including square wave pulse injection, sine wave pulse injection, and sawtooth wave pulse injection.

6. The pulse jet mixing enhanced flow control device according to claim 1, 2 or 3, characterized in that: The incoming flow control mechanism includes a valve plate and a drive assembly; One end of the valve plate is hinged to the inner wall surface at the inlet of the engine inner flow channel, and the other end is a suspended end; The driving assembly is connected to the valve plate in a transmission manner to drive the valve plate to rotate back and forth periodically, thereby periodically changing the flow area at the inlet of the flow channel in the engine to achieve fanning of the steady-state axial air flow.

7. The pulse injection mixing enhanced flow control device according to claim 6, characterized in that: During the periodic rotation of the valve plate, the suspended end faces the downstream direction of the flow channel in the engine.

8. A flow control method for pulse jet mixing enhancement, characterized in that: Flow control is performed using the flow control device according to any one of claims 1 to 5.

9. A flow control method for pulse injection mixing enhancement, characterized in that: Flow control is performed using the flow control device according to claim 6 or 7; The valve plate has a first state and a second state: When the valve plate is in the first state, the valve plate is in contact with the inner wall surface of the flow channel in the engine; When the valve plate is in the second state, the plane where the valve plate is located is perpendicular to the axial direction of the flow channel in the engine; The process of the valve disc rotating from the first state to the second state is defined as a first rotation stage, and the process of the valve disc rotating from the second state to the first state is defined as a second rotation stage. The first rotation stage and the second rotation stage have the same duration and together constitute a pulsation cycle of the axial pulsating air flow. The initial state of the valve disc is the first state. In the flow control method, after the flow passage in the engine starts to operate: First, the driving assembly is started to drive the valve plate to rotate and keep the fuel injection mechanism closed; When the valve plate rotates to zero to a quarter of a cycle, the fuel injection mechanism is opened.

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