A rotatable switching two-stage fluidic device

Abstract

The application provides a rotatable switching two-stage fluidic device, which comprises a shell, a rotating valve and a nozzle, a mixing cavity is arranged in the shell and is communicated with a first air inlet, the nozzle is installed in the mixing cavity, the rotating valve is installed at the nozzle inlet, two independent fluidic channels are arranged in the nozzle, a second air inlet is arranged on the rotating valve, the second air inlet is communicated with the first fluidic channel or the two fluidic channels by rotating the rotating valve; the nozzle comprises a first-stage nozzle and a second-stage nozzle, the second-stage nozzle is installed at one end of the first-stage nozzle, one end of the second-stage nozzle is inserted into the internal cavity of the first-stage nozzle and extends into the mixing cavity, and the second-stage nozzle is used for preventing vortex at the nozzle outlet.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fluidic device or fuel cell, in particular to a rotatable switching two-stage fluidic device. BACKGROUND

[0002] Proton exchange membrane fuel cell is a kind of high-efficiency electrochemical energy conversion device, using hydrogen as fuel, generating water through reaction, and the power generation efficiency is not limited by Carnot cycle, which meets the needs of future society for high-efficiency, clean and economic energy system. In order to realize the high efficiency operation of fuel cell system, hydrogen supply system will be used to supply excess hydrogen to fuel cell stack, so it is necessary to recycle the hydrogen which has passed through the stack but has not reacted to improve its efficiency.

[0003] At present, aiming at the shortcomings of narrow working range and weak adaptability to load change of the fluidic device, some inventions improve the front end of the traditional single-stage fluidic device, including designing multiple nozzles or double channels to realize dynamic hydrogen supply. Although it can well alleviate the poor adaptability of the fluidic device, the simultaneous work of multiple inlets will cause the mixing of the inlets, resulting in energy loss, reducing the high-speed flow energy, and reducing the entraining capacity of the entraining flow. At the same time, the high speed of the front end will cause the total speed to drop suddenly when directly converging, which will produce vortex, shock and other unstable flow phenomena, so that the airflow in the suction chamber is not mixed uniformly, the boundary layer of the mixed gas flows slowly, and a strong shock wave is formed in the constant volume mixing pipe and moves to the diffuser pipe, affecting the diffusing effect and the outlet pressure of the ejector, thereby reducing the supply pressure into the stack, and finally unable to effectively improve the working efficiency of the fuel cell stack system in this mode.

[0004] In addition, the linearly moving valve core installed in the existing fluidic device occupies a large space due to the linear movement of the valve core, resulting in a large main structure of the fluidic device, which is not conducive to installation on the fuel cell vehicle. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application provides a rotatable switching two-stage fluidic device, which is rotatable to make the second inlet communicate with the first fluid channel or with two fluid channels; the first-stage nozzle is extended from one end of the second-stage nozzle to achieve the effect of axial steps at the outlets of the two entraining channels, preventing vortex, shock and other unstable phenomena caused by the mixing of multiple gas flows at the front end of the multi-channel entraining device. Through the change of the outer profile surface of the second-stage nozzle, the jet gas is guided to move along the wall, keeping uniform mixing with the gas at the outlet of the first entraining channel, reducing energy loss, and using gas shear stress to make the gas mix uniformly, so that the high-speed stable gas flow enters the mixing chamber and is stably supplied to the stack.

[0006] The present application achieves the above technical purpose by the following technical means.

[0007] A rotatable switching two-stage fluidic device, comprising a housing, a rotating valve and a nozzle, one end of the housing is an outlet, the other end of the housing is provided with a first air inlet, the housing is provided with a mixing chamber communicated with the first air inlet, the nozzle is installed in the mixing chamber, the rotating valve is installed at the inlet of the nozzle, the nozzle is provided with two independent fluidic channels, the rotating valve is provided with a second air inlet, the second air inlet is communicated with the first fluidic channel or two fluidic channels by rotating the rotating valve;

[0008] The nozzle comprises a primary nozzle and a secondary nozzle, the primary nozzle is located in the mixing chamber, and the primary nozzle is installed at the other end of the housing; the secondary nozzle is installed at one end of the primary nozzle, and one end of the secondary nozzle is inserted into the internal cavity of the primary nozzle, the space between the shell of the secondary nozzle and the internal cavity of the primary nozzle is the first fluidic channel, and the central hole in the secondary nozzle is the second fluidic channel; one end of the secondary nozzle penetrates through the internal cavity of the primary nozzle and extends into the mixing chamber, so as to prevent vortex at the outlet of the nozzle.

[0009] Further, the rotating valve comprises a valve core, a second air inlet and a sealing assembly; the valve core is rotatably installed at one end of the secondary nozzle; at least one layer of sealing assembly is arranged between the valve core and the secondary nozzle; the valve core is connected with a servo motor for driving the valve core to rotate; the valve core is provided with at least two groups of second air inlets with different phase angle distributions, the second air inlets with different phase angle distributions are individually or simultaneously communicated with the corresponding communication holes with different phase angles on the shell of the secondary nozzle by rotating the valve core, so as to make the second air inlets communicated with the first fluidic channel or two fluidic channels.

[0010] Further, the secondary nozzle is provided with a central blind hole, and the other end of the secondary nozzle is provided with a plurality of first communication holes communicated with the first fluidic channel; the other end of the secondary nozzle is provided with a plurality of second communication holes with different phase angles from the first communication holes, each second communication hole is communicated with the central blind hole through a channel, and the channel is in a spiral or inclined shape, so as to make the gas entering the central blind hole produce a rotational flow.

[0011] Further, the internal cavity of the primary nozzle is sequentially provided with a transition section, a tapered section and a jet section according to the flow direction; one end of the secondary nozzle is sequentially provided with a tapered shell and a guide end according to the flow direction; the guide end is inserted into the jet section, so that the cross section of the outlet of the first fluidic channel is annular; one end of the guide end extends out of the end face of the jet section and extends into the mixing chamber.

[0012] Further, the outer contour of the tapered shell is conical, and the jet section is a tapered hole, so as to form a gradually expanding annular outlet at the outlet of the first fluidic channel.

[0013] Further, the outer profile surface of the guide end is sequentially provided with a support surface and a flow guide surface according to the flow direction, the support surface is smoothly connected with the second shell, and the support force is applied to the first injection channel outlet gas, so that the first injection channel outlet gas is kept horizontally advancing; the guide end is a tapered surface, and the mixed gas composed of the second injection channel outlet gas and the gas entering the mixing chamber is obliquely cut into the first injection channel outlet gas along the guide end, so as to moderate the mixing of the two gas flows.

[0014] Further, the inclination angle of the flow guide surface increases with the increase of the axial length of the guide end.

[0015] Further, the injection section is a tapered hole, the taper of the flow guide surface is the same as the taper of the tapered hole of the injection section, and the directions are opposite.

[0016] Further, the injection section inner hole is separated into several support sections by several grooves extending along the axis, and the several support sections are used for supporting the guide end; the flow area of the grooves gradually changes along the axial direction.

[0017] Further, the distance from the one end of the secondary nozzle protruding out of the primary nozzle end surface to the cross section at the outlet of the mixing chamber is NXP, and NXP is 0.8-1.1Dm, wherein Dm is the nominal diameter of the outlet of the mixing chamber.

[0018] The beneficial effects of the present application are:

[0019] 1. The rotatable switching two-stage jet flow device provided by the present application, by protruding the one end of the secondary nozzle out of the primary nozzle end surface, the axial step effect of the two injection channel outlets is achieved, and the unstable phenomena such as vortex and oscillation caused by the simultaneous mixing of multiple gas flows at the front end of the multi-channel ejector are prevented. The distance from the one end of the secondary nozzle protruding out of the primary nozzle end surface to the cross section at the outlet of the mixing chamber is NXP, and when NXP is 0.8-1.1Dm, the entrainment effect and the gas flow mixing effect are optimal.

[0020] 2. The rotatable switching two-stage jet flow device provided by the present application, at least two groups of second air inlets with different phase angle distributions are arranged on the valve core, the second air inlets with different phase angle distributions are individually or simultaneously communicated with the corresponding different phase angle communication holes on the secondary nozzle shell through the rotation of the valve core, so as to make the second air inlets communicate with the first jet flow channel or with two jet flow channels; in this way, the linear moving valve core in the prior art can be avoided, and the problems of large space of the jet flow device and complex installation can be solved.

[0021] 3. The rotatable switching double-stage fluidic device of the present application, the guide end is inserted into the jet section, the first fluid channel outlet cross section is annular, the outer profile surface of the guide end is sequentially provided with a support surface and a guide surface according to the flow direction, the support surface keeps the first jet channel outlet gas advancing horizontally by exerting a support force on the first jet channel outlet gas; the guide surface is a tapered conical surface, the mixed gas composed of the second jet channel outlet gas and the gas entering the mixing chamber obliquely cuts into the first jet channel outlet gas along the guide surface, and the mixing of the two gas flows is moderated.

[0022] 4. The rotatable switching double-stage fluidic device of the present application, the jet section is a tapered hole, the taper of the third guide surface is the same in size and opposite in direction to the taper of the jet section tapered hole, which can moderate the mixing process of the two-stage nozzle gas and maintain a high flow rate when the first inlet flow is low.

[0023] 5. The rotatable switching double-stage fluidic device of the present application, a plurality of grooves extending along the axis are provided on the jet section hole to divide the jet section into a plurality of support sections, and the plurality of support sections are used to support the guide end; on the one hand, the second-stage nozzle is connected to the first-stage nozzle at one end and inserted into the first-stage nozzle at the other end, and the other end of the second-stage nozzle inserted into the first-stage nozzle is in a suspended state, although the length of the second-stage nozzle is short, this cantilever will not affect the first fluid channel in a short time, and the fluidic also plays a certain supporting role; however, long-term use will cause the cantilever end to generate vibration waves due to vibration or shaking during use, which will affect the pressure and flow direction of the fluidic, therefore, the present application can support the other end of the second-stage nozzle through the support section, and the grooves still maintain the function of the first fluid channel, which is composed of a plurality of grooves at this time; on the other hand, the grooves are spaced, which can obtain a more optimal cycle ratio under the joint action of the second fluid channel, utilize the gas shear stress to make the gas mix uniformly, and enter the mixing chamber with high-speed stable gas flow and stably supply the electric pile. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description, and the drawings in the following description are some embodiments of the present application, and for ordinary skilled in the art, other drawings can also be obtained without paying creative labor under the premise of these drawings.

[0025] Figure 1 The structure diagram of the rotatable switching double-stage fluidic device of the present application.

[0026] Figure 2 The structure diagram of the double-stage fluidic device of embodiment 1.

[0027] Figure 3This is a structural diagram of the secondary nozzle in Example 1.

[0028] Figure 4 This is a right view of the secondary nozzle of Example 1.

[0029] Figure 5 This is a right view of the valve core of Example 1, wherein... Figure 5a This is a schematic diagram showing the connection between the second air inlet 3-2 and the first jet channel; Figure 5b This is a schematic diagram showing the second air inlet 3-2 connected to the first jet channel and the second jet channel, respectively.

[0030] Figure 6 This is a partial view of the two-stage jet ejector structure in Example 2.

[0031] Figure 7 for Figure 6 A magnified view of a portion of the image.

[0032] Figure 8 This is a structural diagram of the secondary nozzle in Example 2.

[0033] Figure 9 This is a diagram showing the specific location of the NXP distance in this invention.

[0034] Figure 10 This is a partial view of the two-stage jet ejector structure in Example 3.

[0035] Figure 11 for Figure 10 The sectional view in the image.

[0036] Figure 12 This is a simulation diagram of a single-stage two-stage jet ejector in existing technology.

[0037] Figure 13 This is a simulation diagram of a two-stage jet ejector in operation using existing technology.

[0038] Figure 14 This is a simulation diagram of the single-stage operation of the two-stage jet injector in Embodiment 1 of the present invention.

[0039] Figure 15 This is a simulation diagram of the two-stage jet ejector in Embodiment 1 of the present invention during two-stage operation.

[0040] Figure 16 This is a simulation diagram of the single-stage operation of the two-stage jet injector in Embodiment 3 of the present invention.

[0041] Figure 17 This is a simulation diagram of the two-stage jet ejector in Embodiment 3 of the present invention during two-stage operation.

[0042] In the picture:

[0043] 1 - housing; 1 -1 - mixing chamber; 2 - first air inlet; 3 - rotary valve; 3 -1 - valve core; 3 -2 - second air inlet; 3 -2 -1 - A phase angle air inlet; 3 -2 -2 - B phase angle air inlet; 3 -3 - sealing ring; 3 -4 - rotary seal; 4 - servo motor; 5 - primary nozzle; 5 -1 - transition section; 5 -2 - tapered section; 5 -3 - jet section; 6 - secondary nozzle; 6 -1 - leading end; 6 -2 - tapered housing; 6 -3 - second communication hole; 6 -4 - channel; 6 -5 - central blind hole; 6 -6 - first communication hole; 6 -1 -1 - flow guide surface; 6 -1 -2 - support surface; 5 -3 -1 - groove; 5 -3 -2 - support section. DETAILED DESCRIPTION

[0044] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like reference numerals and characters throughout the figures denote the same elements or elements having the same function. The embodiments described below are exemplary and are intended to be illustrative of the present application and are not to be construed as limiting the present application.

[0045] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are merely intended to facilitate the description of the present application and simplify the description, and are not intended to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the present application. In addition, the terms "first", "second" are used only for the purpose of description and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0046] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0047] As Figure 1As shown, the rotatable switching two-stage fluidic device of the present application comprises a housing 1, a rotating valve 3 and a nozzle, one end of the housing 1 is an outlet, a first air inlet 2 is arranged on the other end of the housing 1, a mixing chamber 1-1 in communication with the first air inlet 2 is arranged in the housing 1, the nozzle is installed in the mixing chamber 1-1, the rotating valve 3 is installed at the inlet of the nozzle, two independent jet channels are arranged in the nozzle 4, a second air inlet 3-2 is arranged on the rotating valve 3, the second air inlet 3-2 is in communication with the first jet channel or the two jet channels by rotating the rotating valve 3; in the field of fuel cells, the first air inlet 2 is generally in communication with the mixed gas of unreacted hydrogen and water vapor in the stack; the second air inlet 3-2 is in communication with the hydrogen supply equipment; the valve core action is controlled according to the size of the output power of the fuel cell, so that the fluidic device can work well at different output powers of the fuel cell.

[0048] The nozzle comprises a primary nozzle 5 and a secondary nozzle 6, the primary nozzle 5 is located in the mixing chamber, and the primary nozzle 5 is installed on the other end of the housing 1; the secondary nozzle 6 is installed on one end of the primary nozzle 5, and one end of the secondary nozzle 6 is inserted into the internal cavity of the primary nozzle 5, the space between the shell of the secondary nozzle 6 and the internal cavity of the primary nozzle 5 is the first jet channel, and the central hole in the secondary nozzle 6 is the second jet channel; one end of the secondary nozzle 6 penetrates through the internal cavity of the primary nozzle 4-1 and extends into the mixing chamber 1-1, which is used for preventing vortex at the outlet of the nozzle, and can prevent the front end of the multi-channel eductor from bringing vortex, shock and other unstable phenomena due to the mixing of multiple gas streams at the same time. Figure 11 As shown, the distance from one end of the secondary nozzle 6 protruding from the end face of the primary nozzle 5 to the cross section of the mixing chamber 1-1 outlet is NXP, when NXP is 0.8-1.1Dm, the entrainment effect and gas flow mixing effect are best. The cross section of the mixing chamber 1-1 outlet can be understood as the interface between the constant pressure chamber outlet of the mixing chamber and the constant volume chamber of the mixing chamber. Wherein Dm is the nominal diameter of the mixing chamber outlet.

[0049] Example 1

[0050] As Figure 2As shown, the nozzle 4 includes a primary nozzle 5 and a secondary nozzle 6, the primary nozzle 5 is located in the mixing chamber, the primary nozzle 5 is installed on the other end of the housing 1; the secondary nozzle 6 is installed on one end of the primary nozzle 5, and one end of the secondary nozzle 6 is inserted into the internal cavity of the primary nozzle 5, the space between the shell of the secondary nozzle 6 and the internal cavity of the primary nozzle 5 is the first jet flow channel, and the central hole in the secondary nozzle 6 is the second jet flow channel; the internal cavity of the primary nozzle 5 is sequentially provided with a transition section 5-1, a tapered section 5-2 and a jet section 5-3 according to the flow direction; one end of the secondary nozzle 6 is sequentially provided with a tapered shell 6-2 and a guide end 6-1 according to the flow direction; the guide end 6-1 is inserted into the jet section 5-3, so that the cross section of the outlet of the first jet flow channel is annular; one end of the guide end 6-1 protrudes from the end surface of the jet section 4-1-3 and extends into the mixing chamber 1-1. After the guide end 6-1 is inserted into the jet section 5-3, the single-sided gap between the guide end 6-1 and the jet section 5-3 is not more than 0.1 mm, which is determined according to the flow and pressure required by the low-power output of the fuel cell in combination with the annular first jet flow channel. And the single-sided gap between the guide end 6-1 and the jet section 5-3 is not more than 0.1 mm, which can be considered that one end of the secondary nozzle 6 is installed on the primary nozzle 5, and the small gap of one end of the secondary nozzle 6 is suspended in the secondary nozzle 6; here the single-sided gap between the guide end 6-1 and the jet section 5-3 is different from the gap fit in embodiment 3, the gap fit between the support section 5-3-2 and the guide end 6-1 in embodiment 3 makes the support section 5-3-2 support the guide end 6-1.

[0051] As shown in Figure 3 , Figure 4 and Figure 5 , the rotating valve 3 includes a valve core 3-1, a second air inlet 3-2, a rotary seal 3-4 and a sealing ring 3-3; the valve core 3-1 is rotatably installed on one end of the secondary nozzle 6, and the rotary seal 3-4 is arranged between the valve core 3-1 and the secondary nozzle 6; the valve core 3-1 is connected with the servo motor 4 for driving the valve core 3-1 to rotate; the valve core 3-1 is provided with at least two groups of second air inlets 3-2 with different phase angle distributions, and the rotation of the valve core 3-1 makes the second air inlets 3-2 with different phase angle distributions and the corresponding different phase angle communication holes on the shell of the secondary nozzle 6 individually or simultaneously conductive, for making the second air inlets 3-2 communicate with the first jet flow channel or with two jet flow channels. The sealing ring 3-3 is arranged on the end surface of the second air inlet 3-2, which is generally an O-ring.

[0052] The valve core 3-1 described in embodiment 1 is provided with two groups of A phase angle inlet ports 3-2-1 and B phase angle inlet ports 3-2-2 with different phase angle distribution; the phase angle of the A phase angle inlet port 3-2-1 and the B phase angle inlet port 3-2-2 is 35° counterclockwise. The A phase angle inlet port 3-2-1 and the B phase angle inlet port 3-2-2 are respectively connected to the hydrogen supply system through the combination of a hose and a hard pipe. The secondary nozzle 6 is provided with a central blind hole 6-5, and the other end of the secondary nozzle 6 is provided with a plurality of first communication holes 6-6 connected to the first jet channel; the other end of the secondary nozzle 6 is provided with a plurality of second communication holes 6-3 at different phase angles with the first communication hole 6-6, each second communication hole 6-3 is connected to the central blind hole 6-5 through a channel 6-4, and the channel 6-4 is spiral or inclined, for generating a rotational flow of the gas entering the central blind hole 6-5. As shown in Figure 4 , the first communication hole 6-6 and the second communication hole 6-3 are both arc-shaped waist holes, the included angle of the arc-shaped waist hole of the first communication hole 6-6 is 20°, and the included angle of the arc-shaped waist hole of the second communication hole 6-3 is 10°, and the phase angle of the first communication hole 6-6 and the second communication hole 6-3 is 35° counterclockwise. As shown in Figure 5a , only the first communication hole 6-6 is connected to the B phase angle inlet port 3-2-2, and the A phase angle inlet port 3-2-1 cannot be connected to the second communication hole 6-3, the valve core 3-1 is rotated by 20°, as shown in Figure 5b , the first communication hole 6-6 is connected to the B phase angle inlet port 3-2-2, and the A phase angle inlet port 3-2-1 is connected to the second communication hole 6-3.

[0053] Working process: when the output power of the fuel cell is less than the set power, the valve core 3-1 is rotated to the position shown in Figure 5a , the first communication hole 6-6 is connected to the B phase angle inlet port 3-2-2, so only the first jet channel is connected to the second inlet port 3-2; the gas ejected from the first draft channel generates a low pressure area a at the nozzle outlet in the mixing chamber 1-1. When the output power of the fuel cell is greater than or equal to the set power, the valve core 3-1 is rotated to the position shown in Figure 5bWhen the guide end 6-1 is in the position shown in the figure, the first communication hole 6-6 is in communication with the B-phase angle air inlet 3-2-2, and the A-phase angle air inlet 3-2-1 is in communication with the second communication hole 6-3, that is, the first and second injection channels are in communication with the second air inlet 3-2, respectively; the gas jetted from the first and second jet channels generates a low-pressure area b in the mixing chamber, and the low-pressure area a can suck and mix the gas in the first air inlet 2 and make it enter the low-pressure area b through the second nozzle 6, so that the gas in the first air inlet 2 and the gas in the second air inlet 3-2 are mixed in the mixing chamber 1-1, and the outlet of the chamber 1 is in communication with the stack. Each of the second communication holes 6-3 is in communication with the central blind hole 6-5 through a channel 6-4, which is in a spiral or inclined shape, so that the gas entering the central blind hole 6-5 generates a rotational flow, and the rotational flow accelerates the jet speed and pressure of the second jet channel.

[0054] The outer contour of the tapered shell 6-2 is conical, and the jetting section 5-3 is a tapered hole, which is used to form a diverging annular outlet at the outlet of the first jet channel.

[0055] The outer contour surface of the guide end 6-1 is provided with a support surface 6-1-2 and a flow guide surface 6-1-1 in sequence according to the flow direction, one side of the support surface 6-1-2 is smoothly transitioned with the second section shell 4-2-2, and the support force is applied to the gas at the outlet of the first injection channel, which is used to make the gas at the outlet of the first injection channel keep advancing horizontally; the guide end 6-1 is a tapered conical surface, and the mixed gas composed of the gas at the outlet of the second injection channel and the gas entering the mixing chamber cuts into the gas at the outlet of the first injection channel along the guide end 6-1, which is used to moderate the mixing of the two gas flows. The flow surface 6-1-1 applies a support force to the mixed gas composed of the gas at the outlet of the first injection channel and the jet gas, and the support force is perpendicular to the wall-attached motion direction of the mixed gas, so that the mixed gas keeps advancing at a high speed after mixing.

[0056] Embodiment 2

[0057] On the basis of embodiment 1, embodiment 2 is as shown in the figures Figure 6 and Figure 7 The tapered shell 6-2 is located in the tapered section 5-2, and the tapered shell 6-2 has a tapered surface with the same taper as the tapered section 5-2; the jetting section 5-3 is a tapered hole, and the taper of the flow guide surface 6-1-1 is the same in size and opposite in direction to the taper of the tapered hole of the jetting section 5-3. That is, if the taper of the outer contour of the flow guide surface 6-1-1 is positive taper β, then the taper of the tapered hole of the jetting section 5-3 is negative taper α. In this way, a diverging annular outlet can be formed at the outlet of the first jet channel, and a larger low-pressure area a can be generated. At the same time, the cross-sectional area of the first injection channel is smaller, which can maintain a higher flow rate when the flow rate of the first air inlet is lower. The included angle β between the flow guide surface 6-1-1 and the axial direction is 4-15 degrees.

[0058] The support surface 6-1-2 in Example 2 is very short, and in some examples, the outer profile surface of the guide end 6-3 is only the flow guide surface 6-1-1, as shown in Figure 8 Figure 8 In some examples, the inclination angle of the flow guide surface 6-1-1 increases with the increase of the axial length of the guide end 4-2-3. Figure 8 In some examples, the flow guide surface 6-1-1 has two sections, respectively forming a first included angle β1 and a first included angle β2, and the first included angle β2 is greater than the first included angle β1. In this way, the flow guide surface 6-1-1 exerts a shear stress on the entrained jet gas, and the mixed gas composed of the gas entering the mixing chamber and the gas at the outlet of the second ejector passage is obliquely cut into the gas at the outlet of the first ejector passage along the flow guide surface 6-1-1 and mixed, which can greatly alleviate the mixing process of the two gas flows.

[0059] Example 3

[0060] Since one end of the secondary nozzle 6 is connected with the primary nozzle 5, and the other end of the secondary nozzle 6 is inserted into the primary nozzle 5, and the other end of the secondary nozzle 6 inserted into the primary nozzle 5 is in a suspended state, although the length of the secondary nozzle is relatively short, this cantilever will not affect the first jet passage for a short time, and the jet also plays a certain supporting role. However, after long-term use, the cantilever end will generate vibration waves due to vibration or shaking during use, which will affect the pressure and flow direction of the jet. Based on Example 1 or Example 2, Example 3 is shown in Figure 10 and Figure 11 The inner hole of the injection section 5-3 is divided into several support sections 5-3-2 by several grooves 5-3-1 extending along the axis, and the several support sections 5-3-2 are used to support the guide end 6-1. In Example 3, the support section 5-3-2 is in clearance fit with the guide end 6-1, and the fitting accuracy of the shaft hole is equivalent to that of the inner ring and the mounting shaft. The flow area of the groove 5-3-1 gradually changes along the axial direction. Since the grooves 5-3-1 are spaced, a more optimal circulation ratio can be obtained under the joint action of the second jet passage, the gas is uniformly mixed by using the gas shear stress, and the high-speed stable gas flow enters the mixing chamber and is stably supplied to the stack.

[0061] Simulation analysis:

[0062] ​Working condition setting: in order to compare the beneficial effects of the structure of the present application with those of the prior art, the single-stage and double-stage modes of injection are simulated under uniform working conditions. Under the condition of single-stage injection, only the first injection channel is opened, at this time the output current of the fuel cell stack is 62.2 A, the pure hydrogen mass flow rate entering from the second inlet is 0.19 g / s, and the temperature is constant at 25℃. The absolute pressure of the high-temperature mixed gas entering from the first inlet is 131 kPa, and the average temperature is 67℃. The composition of the mixed gas is measured by volume fraction, and the composition is H2:N2:H2O = 90%:5%:5%. Under the condition of double-stage injection, the first injection channel and the second injection channel are opened at the same time, at this time the output power of the fuel cell stack is 155.5 A, the pure hydrogen mass flow rate entering from the second inlet is 0.49 g / s, and the temperature is constant at 25℃. The absolute pressure of the high-temperature mixed gas entering from the first inlet is 206 kPa, and the average temperature is 71℃. The composition of the mixed gas is measured by volume fraction, and the composition is H2:N2:H2O = 85%:7%:8%.

[0063] As shown in Figure 12 , in the single-stage injection of the prior art, due to the high flow rate at the outlet of the second jet channel of the two-stage nozzle 6, there is a velocity boundary layer in the high-speed flow near the outlet of the second jet channel, and part of the fluid falls off to form a vortex due to slow flow. When the working time is longer, the vortex core volume increases, which will affect the high-speed flow, reduce its kinetic energy, and at the same time will combine to form unstable flow forms into the mixing chamber, forming shock waves and other phenomena, affecting the diffuser effect and outlet pressure, thereby reducing the supply pressure into the stack and affecting the working efficiency of the stack system.

[0064] As shown in Figure 13 , in the double-stage injection of the prior art, since the first jet channel and the second jet channel are opened at the same time, the second injection channel has a large cross-sectional area, which will produce a low-pressure area near the high-speed flow at the outlet of the two-stage nozzle 6, attracting the gas at the outlet of the first-stage nozzle to mix, so that the two nozzles work at the same time, causing the intake air to mix with each other, resulting in energy loss and reducing the kinetic energy of the high-speed flow. Affecting the entrainment efficiency, causing shock waves, oscillations and other unstable phenomena in the mixing chamber, which eventually move into the diffuser, affecting the diffuser effect and the outlet pressure of the ejector, thereby affecting the working efficiency of the fuel cell stack system.

[0065] Taking the structure of Example 1 as an example, as shown in Figure 14 , one end of the two-stage nozzle 6 penetrates through the internal cavity of the first-stage nozzle 4-1 and extends into the mixing chamber 1-1, forming an axial step effect at the outlets of the two injection channels. As can be seen from the figure, by guiding the high-speed flow gas at the outlet of the first injection channel, the problems of Figure 12The vortex and airflow near the nozzle exit are unstable, mixing closer to the outlet of the isobaric chamber and entering the isochoric chamber in a stable confluence pattern; for example... Figure 15 As shown, one end of the secondary nozzle 6 passes through the internal cavity of the primary nozzle 4-1 and extends into the mixing chamber 1-1, forming an axial step at the outlet of two ejector channels. This prevents instability phenomena such as vortices and oscillations caused by the simultaneous mixing of multiple airflows at the front end of the multi-channel ejector. Furthermore, the outer angle of the guide nozzle is appropriately set to guide the jet gas along the wall, maintaining a relatively high speed and uniform mixing with the gas exiting the first ejector channel. Simultaneously, by reducing the radial velocity at the outlet of the first ejector channel, the mixing process between the gas exiting the second ejector channel and the gas exiting the first ejector channel, as well as the jet gas, is mitigated, reducing energy loss. Gas shear stress is used to ensure uniform gas mixing, allowing a high-speed, stable airflow to enter the mixing chamber and be stably supplied to the fuel cell stack. As can be seen in the figure, the high-speed gas flows from the first and second ejector channels achieve a smooth transition and convergence at the end of the axial step at the outlet, avoiding issues such as... Figure 13 The mixing flow is uneven due to vortices appearing near the nozzle exit. Simultaneously, the second ejector channel is lengthened, and... Figure 13 In comparison, the high-speed region of its outlet gas is shifted to a position closer to the outlet of the isobaric chamber, resulting in reduced kinetic energy loss.

[0066] like Figure 16 As shown, the second air inlet connecting hole and the secondary nozzle housing connecting hole are independently connected, resulting in a small nozzle outlet flow area. The cross-sectional area changed by rotating the rotary valve core 3-1 is related to... Figure 12 In comparison, while maintaining an effective increase in the cycle ratio, it avoids the drawback of changing the cycle ratio by linearly moving the valve core to alter the NXP. Simultaneously, it avoids the vibration and shaking effects on the cantilever structure caused by gas impact collisions in the first ejector channel during long-term operation. Figure 16 As can be seen, after the gases from the first and second air inlets are mixed, the centerline of the mixed gas is almost coincident with the centerline of the second air inlet, and moves forward in a relatively stable manner, thus solving the problem of radial gas fluctuation caused by structural instability near the nozzle outlet.

[0067] like Figure 17 As shown, the second air inlet connecting hole and the secondary nozzle connecting hole are simultaneously connected, resulting in a large nozzle outlet flow area. Figure 13 In comparison, while maintaining an effective increase in the circulation ratio, it avoids the drawback of changing the circulation ratio by linearly moving the valve core to alter the NXP. Simultaneously, it avoids the vibration and shaking effects on the cantilever structure caused by gas impact collisions between the first and second ejector channels at high flow rates. Figure 17It can be seen that the center line of the second injection channel outlet gas and the mixed gas composed of the first gas inlet and the second gas inlet is approximately coincident with the center line of the second gas inlet, and moves forward in a relatively stable form, solving the gas radial fluctuation factor caused by unstable structure near the nozzle outlet.

[0068] It should be understood that although the present specification is described in terms of various embodiments, not every embodiment contains only one independent technical solution, and the specification is described in this way only for clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

[0069] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present application, and are not intended to limit the protection scope of the present application, and equivalent embodiments or changes made without departing from the spirit of the present application should be included in the protection scope of the present application.

Claims

1. A rotatable, switchable two-stage jet ejector, characterized in that, The device includes a housing (1), a rotary valve (3), and a nozzle. One end of the housing (1) is an outlet, and the other end of the housing (1) is provided with a first air inlet (2). The housing (1) is provided with a mixing chamber (1-1) that communicates with the first air inlet (2). The nozzle is installed in the mixing chamber (1-1). The rotary valve (3) is installed at the inlet of the nozzle. The nozzle is provided with two independent jet channels. The rotary valve (3) is provided with a second air inlet (3-2). By rotating the rotary valve (3), the second air inlet (3-2) is connected to the first jet channel or to the two jet channels. The nozzle includes a primary nozzle (5) and a secondary nozzle (6). The primary nozzle (5) is located inside the mixing chamber and is mounted on the other end of the housing (1). The secondary nozzle (6) is mounted on one end of the primary nozzle (5) and one end of the secondary nozzle (6) is inserted into the internal cavity of the primary nozzle (5). The space between the outer shell of the secondary nozzle (6) and the internal cavity of the primary nozzle (5) is the first jet channel, and the central hole inside the secondary nozzle (6) is the second jet channel. One end of the secondary nozzle (6) passes through the internal cavity of the primary nozzle (5) and extends into the mixing chamber (1-1) to prevent vortex generation at the nozzle outlet. The distance from the end of the secondary nozzle (6) extending from the end face of the primary nozzle (5) to the cross-section at the outlet of the mixing chamber is NXP, where NXP is 0.8~1.1Dm, and Dm is the nominal diameter of the outlet of the mixing chamber.

2. The rotatable and switchable two-stage jet ejector according to claim 1, characterized in that, The rotary valve (3) includes a valve core (3-1), a second air inlet (3-2), and a sealing assembly; the valve core (3-1) is rotatably mounted on one end of the secondary nozzle (6); at least one sealing assembly is provided between the valve core (3-1) and the secondary nozzle (6); the valve core (3-1) is connected to a servo motor (4) for driving the valve core (3-1) to rotate; the valve core (3-1) is provided with at least two sets of second air inlets (3-2) with different phase angle distributions. By rotating the valve core (3-1), the second air inlets (3-2) with different phase angle distributions are connected to the corresponding connecting holes with different phase angles on the housing of the secondary nozzle (6) individually or simultaneously, so that the second air inlet (3-2) is connected to the first jet channel or to the two jet channels.

3. The rotatable and switchable two-stage jet ejector according to claim 2, characterized in that, The secondary nozzle (6) is provided with a central blind hole (6-5). The other end of the secondary nozzle (6) is provided with a plurality of first connecting holes (6-6) that communicate with the first jet channel. The other end of the secondary nozzle (6) is provided with a plurality of second connecting holes (6-3) that are at different phase angles from the first connecting holes (6-6). Each second connecting hole (6-3) is connected to the central blind hole (6-5) through a channel (6-4). The channel (6-4) is spiral or inclined and is used to generate swirling flow of the gas entering the central blind hole (6-5).

4. The rotatable and switchable two-stage jet ejector according to claim 1, characterized in that, The internal cavity of the first-stage nozzle (5) is provided with a transition section (5-1), a tapering section (5-2), and a jetting section (5-3) in sequence according to the flow direction; one end of the second-stage nozzle (6) is provided with a tapering shell (6-2) and a guide end (6-1) in sequence according to the flow direction; the guide end (6-1) is inserted into the jetting section (5-3) so that the cross-section of the outlet of the first jet channel is annular; one end of the guide end (6-1) extends out of the end face of the jetting section (5-3) and extends into the mixing chamber (1-1).

5. The rotatable and switchable two-stage jet ejector according to claim 4, characterized in that, The outer contour of the tapered shell (6-2) is conical, and the injection section (5-3) is a conical hole used to form a gradually expanding annular outlet at the outlet of the first jet channel.

6. The rotatable and switchable two-stage jet ejector according to claim 4, characterized in that, The outer contour surface of the guide end (6-1) is provided with a support surface (6-1-2) and a guide surface (6-1-1) in sequence according to the flow direction. One side of the support surface (6-1-2) smoothly transitions with the tapered shell (6-2). By applying a supporting force to the gas at the outlet of the first ejector channel, it is used to keep the gas at the outlet of the first ejector channel moving horizontally. The guide end (6-1) is a tapered cone surface. The mixed gas composed of the gas at the outlet of the second ejector channel and the gas entering the mixing chamber is inclined to cut into the gas at the outlet of the first ejector channel along the guide end (6-1) to moderate the mixing of the two airflows.

7. The rotatable and switchable two-stage jet ejector according to claim 6, characterized in that, The tilt angle of the guide surface (6-1-1) increases with the increase of the axial length of the guide end (6-1).

8. The rotatable switchable two-stage jet ejector according to claim 6, characterized in that, The injection section (5-3) is a conical orifice, and the taper of the guide surface (6-1-1) is the same as the taper of the conical orifice of the injection section (5-3), but in the opposite direction.

9. The rotatable and switchable two-stage jet ejector according to claim 4, characterized in that, The inner hole of the spray section (5-3) is divided into several support sections (5-3-2) by several grooves (5-3-1) extending along the axis, and the several support sections (5-3-2) are used to support the guide end (6-1); the flow area of ​​the grooves (5-3-1) gradually changes along the axial direction.

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