Pulse injection mixing enhanced flow control device and method

Abstract

The invention discloses a pulse injection mixing enhanced flow control device and method. The device comprises an engine inner flow channel, an incoming flow control mechanism and a fuel injection mechanism. The incoming flow control mechanism is arranged at an inlet of a flow channel in the engine and used for flapping steady-state axial incoming air flow to form unsteady-state high-turbulence axial pulsating incoming air flow. The fuel injection mechanism is arranged on the inner wall face of an inner runner of the engine and used for sequential interval pulse injection of fuel to form unsteady-state and high-turbulivity transverse pulsating fuel jet flow. The pulsation frequency of the axial pulsation air incoming flow is the same as that of the transverse pulsation fuel jet flow, and the pulsation phase difference is smaller than or equal to pi / 2. The invention is applied to the field of fuel non-uniform mixing, and is used for realizing short-distance rapid high-efficiency uniform mixing of reactants and improving the combustion efficiency, the combustion intensity and the pressure gain of a combustion chamber, so that the high-frequency self-sustaining and high-specific impulse output high-efficiency pressurized combustion process of an engine is realized.

Description

Technical Field

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

[0002] For the non-premixed combustion process, the degree of mixing uniformity of reactants within a limited-length configuration has a great influence on combustion efficiency and combustion intensity. In recent years, around the non-uniform mixing process of fuel under the actual transverse injection conditions on the inner wall of the engine, scholars at home and abroad have carried out a large number of studies on the axial steady flow conditions. The results show that under the steady axial low-Mach-number air inflow, there are problems such as uneven fuel distribution (fuel is mainly distributed near the wall, while the central flow field is very little) and poor mixing effect of reactants in the transverse steady injection of fuel on the inner wall of the engine with a limited axial length, resulting in incomplete combustion and limited combustion intensity after ignition, leading to limited pressure gain of the supercharged combustion engine and thrust performance far from expectations.

[0003] To address the above problems, the traditional solutions mainly include the following two: 1. Increase the axial length of the engine, so that the reactants form a relatively good mixing effect downstream at a relatively far distance from the engine inlet. 2. Increase the fuel injection pressure, so as to forcibly increase the penetration depth of the fuel and form a relatively good mixing effect within a short axial length. However, both of the above two solutions will significantly increase the geometric size and cost of the engine.

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

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

[0006] To achieve the above object, the present invention provides a flow control device for enhancing pulse injection mixing, including an engine internal flow passage, an incoming flow control mechanism and a fuel injection mechanism; The incoming flow control mechanism is arranged at the inlet of the engine internal flow passage and is used to fan the steady axial air incoming flow, so as to form an unsteady and strongly turbulent axial pulsating air incoming flow in the engine internal flow passage; The fuel injection mechanism is arranged on the inner wall surface of the engine internal flow passage and is used for sequential intermittent pulse injection of fuel, so as to form an unsteady and strongly turbulent transverse pulsating fuel jet in the engine internal flow passage; 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.

[0007] 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.

[0008] 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.

[0009] In one embodiment, the steady-state axial air flow is a low Mach number air flow of Ma0-Ma3.0.

[0010] 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.

[0011] In one embodiment, 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 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.

[0012] 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.

[0013] 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; 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 internal flow passage of the engine starts to operate: First, start the drive assembly to drive the valve plate to rotate and keep the fuel injection mechanism closed; When the valve plate rotates to the range of zero to one-fourth of a cycle, the fuel injection mechanism is opened.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention utilizes the principle that the periodic addition of mass into a smooth tube can generate a resonance enhancement effect, thereby driving and enhancing the pulsation degree of the fluid in the flow passage and the mixing effect of the reactants. By arranging an oncoming flow control mechanism and a fuel injection mechanism on the internal flow passage of the engine, an axial pulsating oncoming air flow and a transverse pulsating fuel jet are generated in the internal flow passage of the engine, and the pulsation frequencies of the axial pulsating oncoming 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 short-distance and rapid high-efficiency and uniform mixing of reactants, improving the combustion efficiency, combustion intensity and pressure gain of the combustion chamber, and thus improving the thrust performance of the supercharged combustion engine. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0016] Figure 1 Schematic diagram of a flow control device for pulsed injection mixing enhancement in an embodiment of the present invention; Figure 2 Schematic diagram of transverse pulsed injection of circumferential wall fuel in an embodiment of the present invention; Figure 3 Schematic diagram of a square-wave pulsed injection mode of fuel in an embodiment of the present invention; Figure 4 Schematic diagram of the mixing degree along the way of a steady-state transverse fuel jet injected under a steady-state air oncoming flow in an embodiment of the present invention; Figure 5 Schematic diagram of the mixing degree along the way of an axial pulsating air oncoming flow and a transverse pulsed fuel jet in an embodiment of the present invention.

[0017] Reference numerals in the drawings: internal flow passage 1 of the engine, oncoming flow control mechanism 2, fuel injection mechanism 3, steady-state axial air oncoming flow 4, axial pulsating air oncoming flow 5, transverse pulsating fuel jet 6, normal shock wave 7.

[0018] The realization, functional features and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the accompanying drawings. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0021] In addition, the descriptions such as "first" and "second" in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0022] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. shall be understood in a broad sense. For example, "fixation" may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, a physical connection or a wireless communication connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0023] 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 those of ordinary skill in the art can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0024] As Figure 1 shown, a flow control device with enhanced pulsed jet mixing (hereinafter referred to as "flow control device") disclosed in this embodiment mainly includes an internal flow passage 1 of an engine, an incoming flow control mechanism 2 and a fuel injection mechanism 3.

[0025] The incoming flow control mechanism 2 is arranged at the entrance of the internal flow passage 1 of the engine and is used to fan the steady axial air incoming flow 4, so as to form an unsteady and strongly turbulent axial pulsating air incoming flow 5 in the internal flow passage 1 of the engine. The fuel injection mechanism 3 is arranged on the inner wall surface of the internal flow passage 1 of the engine and is used for the sequential and spaced pulsed injection of fuel, so as to form an unsteady and strongly turbulent transverse pulsating fuel jet 6 in the internal flow passage 1 of the engine. The internal flow passage 1 of the engine has a rectangular cross-section or a 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 frequencies of the axial pulsating air incoming flow 5 and the transverse pulsating fuel jet 6 are the same, and the pulsation phase difference between the axial pulsating air incoming flow 5 and the transverse pulsating fuel jet 6 is less than or equal to π / 2. For example, when the pulsation pressure of the axial pulsating air incoming flow 5 reaches the peak value, the pulsation pressure of the transverse pulsating fuel jet 6 is in the rising stage or reaches the peak value.

[0026] According to the resonance enhancement principle of the generalized Rayleigh criterion, it can be known that the periodic addition of mass into a smooth pipe can generate a resonance enhancement effect, driving and enhancing the pulsation degree of the fluid in the flow passage and the mixing effect of the reactants. Based on this, in this embodiment, the incoming flow control mechanism 2 and the fuel injection mechanism 3 are used to form an axial pulsating air incoming flow 5 and a transverse pulsating combustion jet 6 in the internal flow passage 1 of the engine. Among them, the pulsation frequencies of the axial pulsating air incoming flow 5 and the transverse pulsating fuel jet 6 are the same to ensure that the flow system is in a resonance state, so as to amplify the pulsation amplitude. And the pulsation phase difference between the axial pulsating air incoming flow 5 and the transverse pulsating fuel jet 6 is less than or equal to π / 2, so that the energies of the axial pulsating air incoming flow 5 and the transverse pulsating fuel jet 6 are superimposed rather than cancelled, 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 short-distance and rapid high-efficiency and uniform mixing of reactants, improve the combustion efficiency, combustion intensity and pressure gain after ignition, and thus improve the thrust performance of the pressure-boosted combustion engine.

[0027] In this embodiment, the incoming flow control mechanism 2 includes a valve plate and a driving component. One end of the valve plate is hinged to the inner wall surface at the entrance of the internal flow passage 1 of the engine through a pin shaft, and the other end is a suspended end. The driving component (such as a motor or a pneumatic motor, etc.) is arranged outside the internal flow passage 1 of the engine. Part of the pin shaft can extend out of the internal flow passage 1 of the engine, and the driving component is connected to the pin shaft through a gear pair, so that the driving component can drive the valve plate to fan back and forth at a high frequency, thereby periodically changing the flow area at the entrance of the internal flow passage 1 of the engine, that is, the steady axial air incoming flow 4 can be stirred into an unsteady and strongly turbulent axial pulsating air incoming flow 5, so as to achieve the enhancement effect of the mixing degree of the reactants.

[0028] In addition, during the high-frequency reciprocating fanning process of the valve plate, an unstable positive shock wave 7 that is constantly pushed downstream can also be formed in the strongly turbulent flow field, and the positive shock wave 7 can further enhance the mixing degree of the reactants.

[0029] In the specific implementation process, during the periodic reciprocating flapping of the valve plate, the suspended end faces the downstream direction of the internal flow passage 1 of the engine, enabling air to flow better to the downstream and ensuring that fuel contacts sufficient air in the first place.

[0030] It should be noted that in the specific application process, it is not limited to using the valve plate as the oncoming flow control mechanism 2. It is also possible to arrange a synthetic jet actuator or a synthetic double jet actuator, etc. at the inlet of the internal flow passage 1 of the engine. By generating a lateral periodic jet through the actuator, it also has the effect of disturbing the steady axial air oncoming flow 4 and generating an axial pulsating air oncoming flow 5.

[0031] In this embodiment, the fuel injection mechanism 3 includes a number of injection ports arranged circumferentially in the same cross-section within the internal flow passage 1 of the engine, and the injection ports are located downstream of the formation position of the normal shock wave 7. For example, Figure 2 As shown in the circular cross-section of the internal flow passage 1 of the engine, at this time, the fuel injection mechanism 3 includes four injection ports, and the four injection ports are evenly distributed in a cross shape on the inner wall surface of the internal flow passage 1 of the engine. Among them, each injection port can be opened and closed synchronously, or inject fuel at intervals in a preset time sequence.

[0032] In this embodiment, the injection mode of the fuel injection mechanism 3 is Figure 3 The square-wave pulsed injection shown, or non-steady injection modes such as sine-wave or sawtooth-wave pulsed injection can also be adopted. Among them, the non-steady pulsed injection mode can form an annular vortex with a strong entrainment effect near the injection port, further significantly increasing the penetration depth and mixing area of the fuel.

[0033] The axial air oncoming flow 4 in this embodiment is preferably an axial low Mach number air oncoming flow of Ma0 to Ma3.0, so as to achieve an optimal balance among the resonance enhancement effect, mixing efficiency, combustion stability, and engineering feasibility.

[0034] This embodiment also discloses a flow control method for enhancing pulse injection mixing, which performs flow control by using the above-mentioned flow control device. Taking the incoming flow control mechanism 2 composed of a valve plate and a driving component as an example, it is defined that the valve plate has a first state and a second state: when the valve plate is in the first state, the valve plate fits against the inner wall surface of the engine internal flow passage 1, that is, the flow area at the inlet of the engine internal flow passage 1 is the largest at this time; 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 passage 1, that is, the flow area at the inlet of the engine internal flow passage 1 is the smallest at this time. At the same time, it is defined that the process of the valve plate rotating from the first state to the second state is the first rotation stage, and the process of the valve plate rotating from the second state to the first state is the second rotation stage. The first rotation stage and the first rotation stage have the same time and jointly form a pulsation period of the axial pulsating air incoming flow 5. The initial state of the valve plate is the first state. In the flow control method, after the engine internal flow passage 1 starts to operate, the driving component is first started to drive the valve plate to rotate, and the fuel injection mechanism 3 is kept closed; when the valve plate rotates to zero to one-quarter of a cycle, the fuel injection mechanism 3 is opened, and the pulsation frequencies of the axial pulsating air incoming flow 5 and the transverse pulsating combustion jet 6 are kept the same, and the pulsation phase difference is less than or equal to π / 2, so as to effectively enhance the mixing degree of air and fuel.

[0035] The following further illustrates the flow control device and method for enhancing pulse injection mixing in this embodiment with specific examples.

[0036] In this example, in a numerical simulation of non-uniform fuel mixing, the flow control device for enhancing pulse injection mixing in this embodiment is adopted, where the inlet cross-sectional size of the engine internal flow passage 1 is 50mm×50mm, the outlet cross-sectional size is Φ40mm, and the total length is 600mm.

[0037] Reference Figure 4 is a schematic diagram of the mixing degree along the way of the steady-state injection of the transverse fuel jet under the steady-state air incoming flow. Figure 5 is a schematic diagram of the mixing degree along the way of the axial pulsating air incoming flow and the transverse pulsed fuel jet. Comparing Figure 4 with Figure 5 it can be seen that, compared with the steady-state injection under the steady-state axial air incoming flow, after adopting the flow control device in this embodiment, the reactants achieve efficient and uniform mixing within a short distance.

[0038] The above are only the preferred embodiments of the present invention, and do not limit the protection scope of the present invention accordingly. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention under the inventive concept of the present invention, or any direct / indirect application in other related technical fields is included in the protection scope of the present invention.

Claims

1. A flow control device with enhanced mixing by pulsed injection, 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 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 and the transverse pulsating fuel jet is the same, 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.

2. The flow control device with pulse jet mixing enhancement 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 flow control device with pulse injection mixing enhancement 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 pulsed jet mixing enhanced flow control device according to claim 1 or 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 pulsed jet mixing enhanced flow control device according to claim 1 or 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 pulsed injection mixing enhanced flow control device according to claim 1 or 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 pulsed jet 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 enhanced by pulsed jet mixing, 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 enhancing mixing by pulsed injection, 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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