CN112443518A - Supersonic air ejector - Google Patents
Supersonic air ejector Download PDFInfo
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- CN112443518A CN112443518A CN202011322584.6A CN202011322584A CN112443518A CN 112443518 A CN112443518 A CN 112443518A CN 202011322584 A CN202011322584 A CN 202011322584A CN 112443518 A CN112443518 A CN 112443518A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
- F04F5/00—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow
- F04F5/14—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow the inducing fluid being elastic fluid
- F04F5/16—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow the inducing fluid being elastic fluid displacing elastic fluids
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
- F04F5/00—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow
- F04F5/14—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow the inducing fluid being elastic fluid
- F04F5/16—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow the inducing fluid being elastic fluid displacing elastic fluids
- F04F5/20—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow the inducing fluid being elastic fluid displacing elastic fluids for evacuating
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
- F04F5/00—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow
- F04F5/44—Component parts, details, or accessories not provided for in, or of interest apart from, groups F04F5/02 - F04F5/42
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
- F04F5/00—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow
- F04F5/44—Component parts, details, or accessories not provided for in, or of interest apart from, groups F04F5/02 - F04F5/42
- F04F5/48—Control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
- F04F5/00—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow
- F04F5/44—Component parts, details, or accessories not provided for in, or of interest apart from, groups F04F5/02 - F04F5/42
- F04F5/48—Control
- F04F5/52—Control of evacuating pumps
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
- G01M9/02—Wind tunnels
- G01M9/04—Details
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Jet Pumps And Other Pumps (AREA)
Abstract
The invention provides a supersonic air ejector, which comprises an air inlet pipe, a pressure-resistant shell, a mixed diffuser pipe and a plurality of groups of ejector pipes, wherein the air inlet pipe, the pressure-resistant shell and the mixed diffuser pipe are sequentially connected; the outlet end of the injection pipe is a Laval nozzle which is uniformly distributed at the inlet section of the mixed diffuser pipe; the air source of each group of the injection pipes is one path, and multiple paths of air sources are independently controlled. The invention adopts a method of installing ejector pipes, the layout of the Laval nozzle is uniform, different numbers of ejector pipes are selected according to the flow requirement, ejectors with different flow specifications can be formed, the area ratio of the ejector is changed by selectively opening the Laval nozzle, the ejector coefficient and the pressure ratio of the ejector are maintained, the airflow parameters are adjusted to maintain the ejector to work near the design point, the highest efficiency is achieved, and the standardization is easy to realize.
Description
Technical Field
The invention relates to the field of aerodynamics, in particular to an air ejector in wind tunnel equipment, and especially relates to a supersonic air ejector which is large in airflow contact area, high in mixing efficiency and flexible to adjust.
Background
The air ejector is a fluid machine, has the function of vacuumizing, takes normal-temperature air as a medium, and is widely applied to the fields of aerospace, military and national defense, national industry and the like. The supersonic ejector has the advantages of simple structure, small volume, rapid reaction and the like, and the pressure recovery system of the rocket engine high-altitude test bed, the hypersonic wind tunnel, the pneumatic laser and the chemical laser reaches the mature application degree.
The ejector mode for the conventional hypersonic wind tunnel at present comprises the following steps: single spray pipe central injection, annular injection, multi-spray pipe injection and the like. The single-nozzle central ejector is concentrated in jet flow and high in noise, and is mostly applied to small-caliber ejector occasions; the annular ejector is peripheral jet flow, has low noise and low pressure ratio, and is mature in application on small and medium-sized wind tunnels; the multi-nozzle ejector and the mixing chamber adopt a multi-nozzle layout, solve the exhaust pressurization of a large-caliber wind tunnel, and are often applied to occasions with low pressurization ratio.
The structure of the ejector belongs to the structure of a slender body, the lengths of a mixing chamber and a diffusion section are correspondingly increased along with the increase of the diameter of a port, the mixed air flow can be uniformly mixed in the mixing chamber, and the high-efficiency diffusion is realized in the diffusion section; for example, the length of a single-stage ejector of a 1.0 m-magnitude super wind tunnel is more than 10 m; if a higher pressure increase ratio is required, the exhaust system reaches more than 30 meters by adopting 3 levels; the equipment layout and the adopted transverse length are too large, and a large amount of equipment investment is occupied.
For a large chemical laser, a high-power ejector is needed for pressurization and exhaust; large hypersonic wind tunnels require an exhaust system with a large caliber and a high pressure ratio. However, the traditional ejector form is large in size, and low in efficiency when the pressure increase ratio is high.
Over the years, various ideas are provided for miniaturizing an injection system and reducing the length and size. The research of the multi-nozzle ejector shows a certain advantage in the aspect of shortening the length, and attracts domestic and foreign scholars to carry out research on the aspect, but the actual practical equipment and the multi-nozzle design method show that no relevant and mature research results exist in the application of large wind tunnels at present.
Although the supersonic ejector system is simple in structure, when the aperture is large, the supersonic ejector system can eject the flow field in the diffusion pipeline extremely complicated, the ejector is not designed properly, interaction and interference exist in some unclear phenomena, the ejector efficiency is greatly reduced, and waste of power energy is caused. If a small ejector parallel mode is adopted, large equipment investment and complex control links are needed, especially when the ejector units are connected in parallel, the transverse occupied area is large, although the principle is feasible, the construction is unrealistic.
According to the existing experience, the ejector is used in a wind tunnel, a flow field of a starting stable operation time sequence is gradually established, the starting pressure is higher than the operation pressure for overcoming the influence of back pressure, the pressure reduction operation after starting is realized, the pressure is matched to the most energy-saving state, and the ejector is theoretically used or has the energy-saving and noise-reducing potential; according to the existing ejector control mode, no corresponding conditions or relevant researches are provided on hardware or a control program.
On the other hand, the multi-nozzle air supply of the existing domestic and foreign wind tunnel ejector is made into the same air source, and the adjustment of the corresponding ejector characteristic cannot be completed, so that the performance is improved, the operating condition of the ejector is improved, and no application example research is available. Theoretically speaking, the flow regulation of the ejector is realized, part of the ejector spray pipe is closed, and f is increased equivalently3/fp*Increasing the injection coefficient; opening part of the nozzle, corresponding to a reduction of f3/fp*And the adjusting range of the ejector is expanded. When ejector backpressure rose, can maintain unchangeable injection coefficient through adjusting the ejector. Therefore, energy saving of the ejector can be realized by introducing a flow adjusting means.
However, independent air supply and flexible layout of the spray pipe are required for realizing two functions of pressure reduction operation and flow regulation.
In the existing multi-nozzle ejector design mode, how to achieve high efficiency through parameter control; and the characteristic of the ejector is combined, and a related adjusting scheme is designed, so that the external parameter control is realized, and the key for solving the efficiency of the large-caliber ejector is realized at present.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects of the prior art and provide the multi-nozzle supersonic air ejector which is compact in structure, easy to operate, capable of independently adjusting an air source, capable of realizing energy-saving control and convenient to process and manufacture.
The scheme for solving the technical problems is as follows:
an ultrasonic air ejector comprises an air inlet pipe, a pressure-resistant shell, a mixed diffuser pipe and a plurality of groups of ejector pipes which are connected in sequence,
the multiple groups of injection pipes are arranged at different cross-section positions of the pressure-resistant shell, and are uniformly distributed in an injection passage coaxial with the air inlet pipe;
the outlet end of the injection pipe is a Laval nozzle which is uniformly distributed at the inlet section of the mixed diffuser pipe;
the air source of each group of the injection pipes is one path, and multiple paths of air sources are independently controlled.
Furthermore, the Laval nozzles are uniformly distributed in a plurality of circles at the inlet section of the mixed diffuser pipe, and the number of the nozzles in each circle is more than or equal to 3.
Furthermore, the sizes and the number of the throats of different Laval nozzles are selected to be matched with the flow area of the fixed mixing diffuser pipe, so that different injection area ratios are formed.
Further, the Ma number range of the Laval nozzle is as follows: ma is more than or equal to 1.5 and less than or equal to 4.
Furthermore, three groups of injection pipes are respectively arranged at three cross-section positions of the pressure-resistant shell;
and at the inlet section of the mixed diffuser pipe, the inner ring and the outer ring of the outlet of the Laval nozzle of the ejector pipe are distributed.
Further, 8 ejector pipes are uniformly arranged on the section C of the pressure shell, and the outlet of the Laval nozzle is positioned on the inner ring of the inlet section of the mixed diffuser pipe;
8 ejector pipes are respectively and uniformly arranged on B, C sections of the pressure shell, and the outlet of the Laval nozzle is positioned on the outer ring of the inlet section of the mixed diffuser pipe.
Further, the ejector tube includes:
the injection pipe seat is arranged on the pressure shell;
the injection nozzle is arranged on the injection pipe seat, one end of the injection nozzle is an air inlet end, and the other end of the injection nozzle is a Laval nozzle.
Furthermore, the air inlet end of the injection spray pipe is positioned outside the pressure shell and is provided with a threaded joint;
the Laval nozzle is positioned inside the pressure shell;
a hollow pipe is arranged between the air inlet end of the injection spray pipe and the Laval spray pipe, and the inner diameter of the hollow pipe is larger than the diameter of a throat of the Laval spray pipe.
Furthermore, a support rib is arranged at the bent part of each injection spray pipe.
Furthermore, the mixed diffuser pipe comprises a straight pipe and an expansion pipe, and the expansion angle of the expansion pipe is 4-7 degrees.
Compared with the prior art, the invention has the advantages that:
(1) the length size of the ejector is effectively reduced, the transverse mixing distance is shortened, the mixing efficiency is improved, and the friction loss of air flow on the pipe wall is reduced. Compared with a single-nozzle ejector, the multi-nozzle ejector has the advantages that the air sources are separately supplied, the starting and the operation are independently controlled, and the system is compact and easy to miniaturize.
(2) The method for installing the ejector pipes is adopted, the layout of the Laval nozzle is uniform, the ejector pipes with different quantities are selected according to flow requirements, ejectors with different flow specifications can be formed, the area ratio of the ejector is changed by selectively opening the Laval nozzle, the ejection coefficient and the pressure ratio of the ejector are maintained, the airflow parameters are adjusted, the ejector works near a design point, the highest efficiency is achieved, and standardization is easy to realize.
(3) Easy to process and manufacture, convenient to adjust and replace and high in injection performance. At present, the existing ejector at home and abroad is produced by depending on a single drawing, the ejector efficiency of the ejector with a fixed size can be known only by debugging the performance of the ejector, and the ejector has the characteristics of single flow specification and weak adaptability. The invention adopts the quantity layout of the ejector pipes, can adjust the flow of the ejector and form ejectors with different flows.
Drawings
The above and other objects, features and advantages of the present disclosure will become more apparent by describing in greater detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.
Fig. 1 is a structural view of a supersonic ejector according to an embodiment of the present invention.
Fig. 2 is a layout diagram of a laval nozzle of the supersonic ejector according to the embodiment of the present invention.
FIG. 3 is a diagram of the supersonic ejector gas inlet section in an embodiment of the present invention.
Fig. 4 is a pressure-resistant housing diagram of the supersonic ejector according to the embodiment of the present invention.
Fig. 5 is a diagram of a supersonic ejector mixing diffuser according to an embodiment of the present invention.
Fig. 6 is a drawing of an ejector tube mounting unit.
FIG. 7 is a drawing of an ejector tube according to an embodiment of the present invention.
Fig. 8 is a drawing of an ejector tube mounting seat according to an embodiment of the present invention.
Fig. 9 is a schematic diagram of an ejector tube gasket according to an embodiment of the present invention.
Fig. 10 is a schematic view of an ejector tube nut according to an embodiment of the present invention.
FIG. 11 is a drawing of a reinforcing rib of an ejector tube according to an embodiment of the present invention.
Reference numerals:
the device comprises an air inlet pipe 1, a pressure-resistant shell 2, an ejector pipe 3, a mixing diffuser pipe 4, an ejector nozzle 3-1, an ejector pipe seat 3-2, a gasket 3-3, a nut 3-4 and reinforcing ribs 3-5.
Detailed Description
Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The invention provides a supersonic air ejector, which comprises an air inlet pipe, a pressure-resistant shell, a mixed diffuser pipe and a plurality of groups of ejector pipes, wherein the air inlet pipe, the pressure-resistant shell and the mixed diffuser pipe are sequentially connected. The multiple groups of injection pipes are arranged at different cross-section positions of the pressure-resistant shell, and are uniformly distributed in an injection passage coaxial with the air inlet pipe; the outlet end of the injection pipe is a Laval nozzle which is uniformly distributed at the inlet section of the mixed diffuser pipe; the air source of each group of the injection pipes is one path, and multiple paths of air sources are independently controlled.
Specifically, the air inlet pipe is connected with a pressure shell, the injection pipe is installed on the injection pipe seat, the injection pipe seat is fixed on the pressure shell, one end of the injection pipe is an air inlet section, the other end of the injection pipe is a laval spray pipe section, and the laval spray pipe sections are uniformly distributed at an inlet of the mixed diffusion pipe. The mixed diffuser pipe is connected with the pressure shell. The air source of the ejector pipe can be independently supplied, and flow regulation and control during starting and running of the ejector are realized. The area ratio of the ejector is changed by selectively opening the ejector spray pipe, and the optimal ejection coefficient and the pressure increase ratio of the ejector are maintained. And the air flow parameters are adjusted to maintain the ejector to work near a design point, so that the highest efficiency is achieved.
Preferably, the ejector pipes can be arranged at different cross-section positions of the pressure-resistant shell of the ejector, and are uniformly distributed in the ejector channel coaxial with the air inlet pipe. High-energy and high-pressure gas enters the ejector through the ejector pipe, supersonic airflow is sprayed out of the Laval nozzle on the same cross section, the high-energy and high-pressure gas is mixed with low-pressure and low-energy ejected airflow through a larger contact area to generate energy exchange, the mixed airflow enters the mixed diffuser pipe, the speed is gradually balanced, and the mixed gas is discharged out of the ejector through smaller pressure loss after the mixed diffuser pipe is decelerated and pressurized along with the rise of pressure.
Preferably, the Laval nozzles are uniformly distributed in a plurality of circles at the inlet section of the mixing diffuser pipe, and the number of the nozzles in each circle is more than or equal to 3.
Preferably, the air inlet pipe is a transition section for stabilizing air flow, the front end of the air inlet pipe is matched with the connection size of the front pipeline, and the rear part of the air inlet pipe is connected with the pressure shell through a flange.
Preferably, the ejector pipe comprises two hollow pipes, the ventilation end is provided with a threaded joint, the inner diameter of the hollow pipe on the other side is larger than the diameter of the throat of the Laval nozzle, and the sectional area ratio is 5.
Preferably, the sizes and the number of the throats of different laval nozzles can be selected to be matched with the flow area of a fixed mixing diffuser pipe to form different injection area ratios, which are key factors for determining the pressure ratio of the injector.
Preferably, the laval nozzle has Ma number in the range of: ma is more than or equal to 1.5 and less than or equal to 4, and the ejector with different pressure ratios is adapted by changing the Mach number of the ejector nozzle.
Preferably, three groups of ejector pipes are installed according to the determined positions of A, B, C three sections, and the inner circle and the outer circle of the outlet of the ejector pipe are distributed on the inlet section of the mixing diffusion section in the pressure-resistant housing. The injection pipe on the pressure shell is divided into three groups of independent air sources for air supply according to the section A, B, C, and flow regulation can be realized.
Preferably, the support rib is welded at the bent part of each injection pipe, so that the rigidity of the injection pipe is increased.
Preferably, the airflow passage of the whole ejector has no reverse step.
Preferably, the mixed diffuser pipe consists of a straight pipe section and an expansion pipe, and the expansion angle of the expansion pipe is 4-7 degrees.
Preferably, the pressure-resistant shell is in a cylindrical shape with flanges at two ends, and the flanges at two ends are respectively used for connecting the air inlet pipe and the mixed diffuser pipe. Three rows of wall surface through holes are uniformly arranged on the cylindrical wall surface; the wall surface through hole is provided with an injection pipe, and 8 bolt holes are uniformly distributed on the periphery of the injection pipe; the bolt hole is used for being connected with an installing flange of the injection pipe.
Preferably, the air inlet pipe, the pressure shell and the mixed diffusion pipe are connected through a mating flange which is sealed by a red copper gasket, and the flange plate is provided with a unthreaded hole which is fastened by bolts.
To facilitate understanding of the solution of the embodiments of the present invention and the effects thereof, a specific application example is given below. It will be understood by those skilled in the art that this example is merely for the purpose of facilitating an understanding of the present invention and that any specific details thereof are not intended to limit the invention in any way.
The principles and features of the present invention are described in detail below with reference to the accompanying drawings.
As shown in fig. 1, the multi-nozzle supersonic ejector of the present embodiment includes: the pressure-resistant pipe comprises an air inlet pipe 1, a pressure-resistant shell 2, an injection pipe 3 and a mixed diffusion pipe 4. The supersonic air ejector with the multiple spray pipes can realize pressurization and vacuumizing of incoming flow. The pressure shell 2 of the ejector is provided with ejector pipes 3 at different cross-section positions, and the ejector pipes 3 are uniformly distributed in an ejector passage coaxial with the air inlet pipe 1. High-energy and high-pressure gas enters the ejector through the ejector pipe 3, supersonic airflow is sprayed out of the Laval nozzle on the same cross section, the high-energy and high-pressure gas is mixed with low-pressure and low-energy ejected airflow through a larger contact area to generate energy exchange, the mixed airflow enters the mixed diffuser pipe 4, the speed is gradually balanced, and along with the rise of pressure, after the mixed diffuser pipe 4 is subjected to speed reduction and pressurization, the mixed gas is discharged out of the ejector through smaller pressure loss.
Specifically, the intake pipe 1 is connected to the pressure-resistant casing 2, and the mixing diffuser pipe 4 is connected to the pressure-resistant casing 2. The injection pipe seat 3-2 is fixed on the pressure shell 2, and the injection nozzle 3-1 is arranged on the injection pipe seat 3-2 and positioned. One end of the injection spray pipe 3-1 is an air inlet section, the other end of the injection spray pipe is a Laval spray pipe section, and the Laval spray pipe sections are uniformly distributed at the inlet section of the mixed diffuser pipe 4. The spray pipes on the outlet section of the Laval spray pipe are distributed into 2 circles, and the number of the spray pipes in each circle is n which is more than or equal to 3.
As shown in fig. 2, the parts mounting diagram shows the mounting positions of the ejector pipes 3 having three cross sections on the pressure casing 2. In this embodiment, three cross-sectional positions, 8 air inlet flange interfaces of every cross-section equipartition, 24 air intakes altogether. At the position of A, B, C three sections, the injection pipe 3 is installed. Specifically, 8 ejector pipes 3 are installed on the section C, and the outlet is the inner ring of the inlet section of the mixing diffuser pipe 4. The air sources of 8 injection pipes 3 are connected together. The two ejector pipes 3 are arranged on the B, C cross section, the outlet of the spray pipe is positioned on the outer ring of the inlet cross section of the mixing diffuser pipe 4, the air sources of the 8 ejector pipes 3 on the B cross section are one path, and the air sources of the 8 ejector pipes 3 on the C cross section are one path; and the optimization of injection parameters is realized by independently controlling three air sources.
As shown in fig. 3, the air inlet pipe 1 is an airflow passage entering the ejector, is a section of transition pipe composed of variable diameter pipes, and is matched with the connection size of the front pipe, so as to rectify and introduce incoming flow. The diameter of the air inlet pipe 1 is determined according to the injection area ratio of the injector, the pipeline flow area of injected airflow is obtained, the pipeline inner diameter is calculated, and the length of the expansion pipe at the rear section is determined according to the expansion angle of 6 degrees and is connected with the pressure shell 2. In this embodiment, the inner diameter of the air inlet pipe 1 is 200mm, the length thereof is 200mm, the length of the expansion section is 200mm, and the air inlet pipe is formed by welding common steel plate coiled pipes.
As shown in fig. 4, the pressure casing 2 is used for bearing the high-pressure air source of the ejector. Inside the pressure casing 2 is a stable inflow chamber, and the airflow flows along the axial direction of the pipeline stably and uniformly. The pressure shell 2 is of a cylindrical structure, and the wall surface of the pressure shell 2 is uniformly provided with a flange structure for installing the injection pipe 3 and introducing high-pressure air according to the designed flow requirement. In this embodiment, three cross-sectional positions, 8 air inlet flange mouths of every cross-section equipartition, 24 air inlets in total. Fig. 4 shows A, B, C three-section position layout, each flange is fixed by 8 screws.
The inner diameter of the pressure shell 2 is selected, the flow area of the pipeline of the injected airflow is obtained according to the injection area ratio of the injector, and the blocking area of the air inlet pipe on the section is added to obtain the inner diameter of the pressure shell 2. The length of the pressure casing 2 is not required in pneumatic calculation, and is mainly a structure suitable for spray pipe layout, so that the pressure casing is convenient to process and install.
As shown in fig. 5, the mixing diffuser pipe 4 is composed of a section of shrink pipe and a section of pipe with equal cross section, and the smooth transition between the two sections of pipes is a key component of the ejector. The front flange of the shrinkage pipe is connected with the flange of the pressure shell 2, the inner diameter of the shrinkage pipe is consistent with the inner diameter of the pressure shell 2, and the length of the shrinkage pipe is determined according to the shrinkage ratio selected by pneumatic calculation parameters and ranges from 2 to 3. The injection coefficient of the embodiment is 2.8, and the optimal injection coefficient is achieved. The diameter of the equal-section pipe is consistent with the outlet of the front contraction pipe, the length of the equal-section pipe is selected according to a design method in high-speed wind tunnel, the length-diameter ratio is 6-8, and the diffusion efficiency is high. In the embodiment, the design use pressure is 0.8MPa, the inner diameter of the equal straight section is 250mm, the length-diameter ratio is 8, and the length is 2 m; the material is common carbon steel, and is formed by rolling and welding 5mm thick plates.
As shown in fig. 6, an assembly view of the machined parts is given in order to explain the step of mounting the ejector tube 3 in detail. The ejector pipe 3 comprises an ejector nozzle 3-1, an ejector pipe seat 3-2, a gasket 3-3, a nut 3-4 and a reinforcing rib 3-5, and is integrally installed, fixed on the pressure-resistant shell 2 through the ejector pipe seat 3-2 and sealed by a red copper gasket.
As shown in fig. 7, the ejector nozzle 3-1 is composed of a section of air inlet pipe and a laval nozzle, the end of the ejector nozzle is connected with an external flared copper pipe through a screwed joint, compressed air is introduced from the air inlet pipe, and supersonic airflow is generated at the outlet of the laval nozzle, and the ejector nozzle is a key component of the ejector unit. The range of Ma numbers is designed as follows: ma is more than or equal to 1.5 and less than or equal to 4. In this embodiment, Ma is 3. The bending radius of the bent pipe is related to the position of the spray pipe on the section of the mixing chamber, and the angle can be selected from the range of 60-90 degrees. The nozzle of this embodiment is designed with three positions, all of which are matched with 90-degree elbows, so the layout is only related to the radial dimension and the axial dimension, and X is1＝20mm、Y1＝40mm，X2＝10mm、Y2＝20mm，X3＝20mm、Y3＝40mm。
As shown in fig. 8, the ejector nozzle holder 3-2 is used for mounting the ejector nozzle 3-1, and is fixed and hermetically connected with the pressure casing 2, and is made of common steel.
As shown in fig. 9, the ejector tube gasket 3-3 is installed on the ejector tube seat 3-2, and is made of common steel, and the embodiment adopts a standard component.
As shown in fig. 10, the injection pipe nut 3-4 has threads matching those of the air inlet end of the injection pipe 3. After the position of the injection pipe section is adjusted, the nut is screwed down, and the injection spray pipe 3-1 is fixed. In the embodiment, a common standard nut M24 is selected.
As shown in figure 11, the shape of the reinforcing rib 3-5 of the ejector pipe 3 is adjusted and matched according to the size of the elbow, and the reinforcing rib is welded and fixed at the inner bending part of the ejector nozzle 3-1 to prevent the elbow from generating larger elastic deformation under stress. In the embodiment, the bent pipe has the outer diameter of 25 degrees, is bent by 90 degrees, and the thickness of the reinforcing ribs 3-5 is 2 mm.
It will be appreciated by persons skilled in the art that the above description of embodiments of the invention is intended only to illustrate the benefits of embodiments of the invention and is not intended to limit embodiments of the invention to any examples given.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (10)
1. A supersonic air ejector comprises an air inlet pipe, a pressure-resistant shell and a mixed diffuser pipe which are connected in sequence, and is characterized by also comprising a plurality of groups of ejector pipes,
the multiple groups of injection pipes are arranged at different cross-section positions of the pressure-resistant shell, and are uniformly distributed in an injection passage coaxial with the air inlet pipe;
the outlet end of the injection pipe is a Laval nozzle which is uniformly distributed at the inlet section of the mixed diffuser pipe;
the air source of each group of the injection pipes is one path, and multiple paths of air sources are independently controlled.
2. The supersonic air ejector according to claim 1, wherein the laval nozzle is evenly distributed with a plurality of circles at the inlet section of the mixing diffuser pipe, and the number of nozzles per circle is more than or equal to 3.
3. The supersonic air ejector according to claim 1, wherein different laval nozzle throat sizes and numbers are selected to match a fixed mixed diffuser flow area to form different ejector area ratios.
4. The supersonic air ejector according to claim 1, wherein the laval nozzle has a Ma number in a range of: ma is more than or equal to 1.5 and less than or equal to 4.
5. The supersonic air ejector according to claim 1, wherein three sets of ejector pipes are provided at three cross-sectional positions of the pressure-resistant casing, respectively;
and at the inlet section of the mixed diffuser pipe, the inner ring and the outer ring of the outlet of the Laval nozzle of the ejector pipe are distributed.
6. The supersonic air ejector according to claim 5, wherein 8 ejector pipes are uniformly installed on the C section of the pressure casing, and the outlet of the laval nozzle is positioned at the inner ring of the inlet section of the mixing diffuser pipe;
8 ejector pipes are respectively and uniformly arranged on B, C sections of the pressure shell, and the outlet of the Laval nozzle is positioned on the outer ring of the inlet section of the mixed diffuser pipe.
7. The supersonic air ejector of claim 1 wherein the ejector tube comprises:
the injection pipe seat is arranged on the pressure shell;
the injection nozzle is arranged on the injection pipe seat, one end of the injection nozzle is an air inlet end, and the other end of the injection nozzle is a Laval nozzle.
8. The supersonic air ejector according to claim 7, wherein the air inlet end of the ejector nozzle is located outside the pressure casing and is provided with a threaded joint;
the Laval nozzle is positioned inside the pressure shell;
a hollow pipe is arranged between the air inlet end of the injection spray pipe and the Laval spray pipe, and the inner diameter of the hollow pipe is larger than the diameter of a throat of the Laval spray pipe.
9. The supersonic air ejector of claim 7 wherein the bend of each ejector nozzle is provided with a support rib.
10. The supersonic air ejector according to claim 1, wherein the mixing diffuser pipe comprises a straight pipe and an expansion pipe, and the expansion angle of the expansion pipe is 4-7 °.
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| CN202011322584.6A CN112443518A (en) | 2020-11-23 | 2020-11-23 | Supersonic air ejector |
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| CN113187770A (en) * | 2021-06-08 | 2021-07-30 | 郭孝国 | Water jet air extractor |
| CN113252290A (en) * | 2021-04-22 | 2021-08-13 | 哈尔滨工业大学 | Mars low-pressure supersonic ejector with ultralow-pressure input and high-wind-speed output |
| CN117928959A (en) * | 2024-03-25 | 2024-04-26 | 中国航空工业集团公司沈阳空气动力研究所 | Ejector type power simulation system of aero-engine icing test bed |
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