Liquid drop evaporation test bed with known flow field parameters

Abstract

The invention provides a liquid drop evaporation test bed with known flow field parameters. The liquid drop evaporation test bed comprises an observation column, an air inlet filter tube, a transverse rectification net, an annular rectification net, a vortex chamber, an exhaust valve, an exhaust filter net, a static dropper, an injection slim tube and an automatic injector, one end of the observation column is fixedly connected with the vortex chamber through the air inlet filter pipe, the transverse rectification net and the annular rectification net; the exhaust valve is mounted in an exhaust hole of the vortex chamber; the static dropper is installed in a static hole of the exhaust filter screen, one end of the injection slim tube is connected with an injection hole of the automatic injector, the other end of the injection slim tube is connected with a dropper hole of the static dropper, the sensor sealing columns are installed in sealing through grooves in the observation column, and the sensors are installed in sensor holes of the sensor sealing columns. According to the invention, the problems of errors, agnostic research results and the like caused by uncontrollable and unmeasurable weak airflow disturbance and determined by liquid surface tension disappearance and gas-liquid interface thickness increase under the transcritical / supercritical condition are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of engine testing, and in particular relates to a droplet evaporation test bench with known flow field parameters. Background Art

[0002] In order to achieve a more efficient and low-pollution engine, technical measures such as high injection pressure, high boost pressure, and high back pressure are widely used. It is not a low-probability phenomenon that the temperature and back pressure in the cylinder are close to and exceed the critical point of the fuel, making transcritical / supercritical spray mixing an unavoidable issue for the engine. Under critical conditions, the density of the liquid phase is significantly reduced, and the gas-liquid interface is difficult to identify. Instead, it is replaced by a gas-liquid two-phase mixing layer mainly controlled by the diffusion process. The appearance of this mixing layer is attributed to the disappearance of the liquid surface tension and the increase in the thickness of the gas-liquid interface. Therefore, the disintegration of the liquid jet and the formation of the mixture are no longer controlled by surface tension and aerodynamic instability, but are controlled by the turbulent diffusion process. At this time, a slight disturbance at the gas-liquid interface can have a significant impact on the diffusion process of the fuel.

[0003] For a long time, the research on transcritical / supercritical spray has been mainly focused on three aspects. The first is the evaporation characteristics of a single droplet under transcritical / supercritical conditions; the second is the state equation of real fluids and the calculation method of thermophysical properties and transport coefficients under transcritical / supercritical conditions; the third is the stability of the transcritical / supercritical jet mixing layer and its evolution process. The existing experimental methods, such as the main work in constant volume combustion bombs, are to study the jet conditions of the spray, which can provide experimental data for the second point mentioned above. However, because the constant volume combustion bomb can only ensure that the flow field environment remains approximately static relative to the dynamic process of the spray, the weak airflow disturbance caused by temperature transfer is difficult to control and measure, which will cause large errors in the data results due to the characteristics of transcritical / supercritical spray.

[0004] Weak airflow disturbances are difficult to observe and control, but if an obviously observable airflow environment is artificially provided, the flow field parameters of the airflow can be observed, and the airflow disturbances caused by chance can also be predicted and controlled. In this way, the errors and unknowns in the research results caused by the uncontrollable and unmeasurable weak airflow disturbances determined by the disappearance of liquid surface tension and the increase of gas-liquid interface thickness under transcritical / supercritical conditions can be reduced, and the evaporation characteristics of a single droplet under transcritical / supercritical conditions can be studied in an environment where the flow field parameters are known; at the same time, because the static dropper and observation column in this equipment provide static and dynamic flow field environments respectively, the comparison of the motion state of the fuel droplet in the two can study the stability and evolution process of the transcritical / supercritical jet mixing layer. Summary of the invention

[0005] In view of this, the present invention aims to propose a droplet evaporation test bench with known flow field parameters to solve the problems of errors and unknowability in research results caused by uncontrollable and unmeasurable weak airflow disturbances determined by the disappearance of liquid surface tension and the increase of gas-liquid interface thickness under transcritical / supercritical conditions, thereby providing the possibility of studying the evaporation characteristics of a single droplet under transcritical / supercritical conditions and the stability and evolution process of the transcritical / supercritical jet mixing layer.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A droplet evaporation test bench with known flow field parameters comprises an observation column, an air inlet filter tube, a transverse rectifying net, an annular rectifying net, a vortex chamber, an exhaust valve, an exhaust filter, a static dropper, an injection capillary and an automatic injector;

[0008] One end of the observation column is tightly connected to the vortex chamber through an air inlet filter tube, a transverse rectifying net, and an annular rectifying net; the exhaust valve is installed in the exhaust hole of the vortex chamber;

[0009] The other end of the observation column is tightly connected to the exhaust filter, the static dropper is installed in the static hole of the exhaust filter, one end of the injection tube is connected to the injection hole of the automatic syringe, and the other end is connected to the dropper hole of the static dropper, several sensor sealing columns are installed in the sealing grooves on the observation column, and the sensors are installed in the sensor holes of the sensor sealing columns.

[0010] Furthermore, the vortex chamber is in the shape of a hollow cylinder with an open circular surface on the top; a cylinder is provided in the center of the bottom of the vortex chamber, which is an air release column, and a through hole is provided in the center of the air release column as an air release hole; an air intake column with a square cross-section is provided in the vortex chamber along the tangent direction of the cylinder, and there is an air intake hole with a square cross-section in the air intake column, and the inner wall of the air intake hole is also tangent to the inner wall of the cylindrical surface of the vortex chamber.

[0011] Furthermore, the annular rectifying net is a hemispherical thin plate, and an annular flat plate is provided at the bottom; the central axis of the annular rectifying net is coaxially placed with the central axis of the vortex chamber, the hemispherical thin plate of the annular rectifying net protrudes upward, and the annular flat plate of the annular rectifying net is closely attached to the top plane of the vortex chamber;

[0012] The transverse rectifying net is a hemispherical thin plate with an annular plane plate at the bottom; its grids are arranged to be parallel to each other in a transverse distribution; the central axis of the transverse rectifying net is coaxially placed with the central axis of the vortex chamber, the hemispherical thin plate protrudes upward, and the annular plane plate of the transverse rectifying net is closely attached to the annular plane plate of the annular rectifying net;

[0013] The air intake filter tube is a hollow cylinder with an open bottom circular surface and parallel horizontally distributed grids arranged on the top circular surface; the central axis of the air intake filter tube is coaxially placed with the central axis of the vortex chamber, and the bottom circular surface of the air intake filter tube is in close contact with the horizontal rectifying net annular plane plate.

[0014] Furthermore, the observation column is a transparent hollow cylinder with circular openings on the upper and lower sides; a longitudinal square gap is opened on the annular cylindrical surface as a sealing groove, and longitudinal long square sealing bosses are arranged on the cylindrical surfaces on both sides of the sealing groove, and sealing screw holes are evenly arranged longitudinally on the sealing bosses on both sides, and the positions of the sealing screw holes on the sealing bosses on both sides correspond horizontally to each other; the central axis of the observation column is coaxially placed with the central axis of the vortex chamber, and the bottom surface of the observation column is close to the top surface of the air intake filter tube.

[0015] Furthermore, the exhaust filter is a hollow cylinder with an open bottom circular surface, parallel horizontally distributed grids arranged on the top circular surface, and a through hole arranged in the center of the top circular surface as a static hole; the central axis of the exhaust filter is coaxially placed with the central axis of the vortex chamber, and the bottom surface of the exhaust filter is close to the top surface of the observation column.

[0016] Furthermore, the static dropper is a transparent hollow long cylinder with an opening on the bottom circular surface and a through hole in the center of the top circular surface as a dropper hole; the static dropper can be placed in the static hole on the exhaust filter, and the bottom surface of the static dropper coincides with the bottom surface of the exhaust filter.

[0017] Furthermore, the automatic syringe is a product consisting of an injection pump and a syringe, and has the function of evenly and slowly pushing a liquid of appropriate mass into an injection tube. There is an injection hole on the automatic syringe.

[0018] Furthermore, the injection tube is a round tube, the shape of which is adapted to the test environment; one end of the injection tube is placed in the dropper hole on the static dropper, and the other end is placed in the injection hole on the automatic injector.

[0019] Furthermore, the sensor sealing column is a column with a "convex"-shaped cross-section, a through hole is arranged in the center of the sensor sealing column along the horizontal direction as a sensor hole, and through holes are arranged in the horizontal direction on both sides of the sensor sealing column along the horizontal direction as sealing holes; a number of sensor sealing columns are placed in the sealing groove and arranged horizontally and longitudinally from top to bottom, and bolts are used to fasten the sensor sealing columns to the observation column through the sealing holes and sealing screw holes.

[0020] Furthermore, the sensor includes a pressure sensor and a temperature sensor, which can measure physical characteristics at corresponding positions in the flow field; the sensor can be placed in the sensor hole of the sensor sealing column, and the measuring end of the sensor is close to the center axis of the vortex chamber. The observation column, the sensor sealing column and the sensor realize the sealing of the internal space of the observation column.

[0021] Compared with the prior art, the droplet evaporation test bench with known flow field parameters described in the present invention has the following advantages:

[0022] (1) The present invention provides a droplet evaporation test bench with known flow field parameters, which artificially provides an observable airflow environment, thereby reducing the error in the research results caused by the uncontrollable and unmeasurable weak airflow disturbance around the droplets in general equipment. The evaporation characteristics of a single droplet under transcritical / supercritical conditions can be studied in an environment where the flow field parameters are known, thereby improving the accuracy and repeatability of the test and reducing the economic cost and time cost of the operation in the test.

[0023] (2) The present invention provides a droplet evaporation test bench with known flow field parameters. Since the static dropper and observation column in the device provide static and dynamic flow field environments respectively, the comparison of the motion state of the fuel droplets in the two can be used to study the stability and evolution process of the transcritical / supercritical jet mixing layer. It is convenient for research and improves the adaptability of the research process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 It is a schematic diagram of the overall structure of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0026] Figure 2 It is a cross-sectional view of the overall structure of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0027] Figure 3 It is a schematic diagram of the overall structure of a vortex chamber of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0028] Figure 4 It is a cross-sectional view of a vortex chamber along the air inlet column of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0029] Figure 5 A cross-sectional view of a vortex chamber of a droplet evaporation test bench with known flow field parameters along a degassing column according to the present invention;

[0030] Figure 6 A schematic diagram of an exhaust valve of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0031] Figure 7 It is an overall schematic diagram of an annular rectifying network of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0032] Figure 8 It is a cross-sectional view of an annular rectifying network of a droplet evaporation test bench with known flow field parameters according to the present invention along the central axis of the annular rectifying network;

[0033] Fig. 9 A top view of a circumferential rectifying network of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0034] Fig.10 It is an overall schematic diagram of a transverse rectifying network of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0035] Fig.11 A cross-sectional view of a transverse rectifying network of a droplet evaporation test bench with known flow field parameters according to the present invention along the central axis of the transverse rectifying network;

[0036] Fig.12 A top view of a transverse rectifying network of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0037] Fig.13 It is an overall schematic diagram of an air intake filter tube of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0038] Fig.14 It is a cross-sectional view of an air intake filter tube of a droplet evaporation test bench with known flow field parameters according to the present invention along the central axis of the air intake filter tube;

[0039] Fig.15 A top view of an air inlet filter tube of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0040] Fig.16 It is an overall schematic diagram of an observation column of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0041] Fig.17 A cross-sectional view of an observation column of a droplet evaporation test bench with known flow field parameters according to the present invention along the central axis of the observation column;

[0042] Fig.18 It is a cross-sectional view of the sealing screw hole of the observation column of the droplet evaporation test bench with known flow field parameters according to the present invention;

[0043] Fig.19 It is an overall schematic diagram of a sensor sealing column of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0044] Fig. 20 A cross-sectional view of a sealing column of a sensor of a droplet evaporation test bench with known flow field parameters along a sealing through hole according to the present invention;

[0045] Fig.21 A schematic diagram of a sensor of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0046] Fig. 22 It is an overall schematic diagram of an exhaust filter screen of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0047] Fig.23 It is a cross-sectional view of an exhaust filter of a droplet evaporation test bench with known flow field parameters according to the present invention along the central axis of the exhaust filter;

[0048] Fig.24 A top view of an exhaust filter screen of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0049] Fig.25 It is an overall schematic diagram of an automatic injector of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0050] Fig.26 It is an overall schematic diagram of an injection capillary of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0051] Fig. 27 A cross-sectional view of an injection capillary of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0052] Fig.28 It is an overall schematic diagram of a static dropper of a droplet evaporation test bench with known flow field parameters according to the present invention;

[0053] Fig.29 This is a cross-sectional view of a static dropper along the dropper hole of a droplet evaporation test bench with known flow field parameters described in the present invention.

[0054] Description of reference numerals:

[0055] 1. Observation column; 11. Sealing groove; 12. Observation column centerline; 13. Sealing boss; 131. Sealing screw hole; 2. Inlet filter tube; 21. Inlet filter tube centerline; 3. Horizontal rectifier net; 31. Hemispherical thin plate of the horizontal rectifier net; 32. Annular plane plate of the horizontal rectifier net; 33. Centerline of the horizontal rectifier net; 4. Annular rectifier net; 41. Hemispherical thin plate of the annular rectifier net; 42. Annular plane plate of the annular rectifier net; 43. Centerline of the annular rectifier net; 5. Eddy current chamber; 51. Eddy current The center axis of the chamber; 52, the exhaust column; 521, the exhaust hole; 53, the intake column; 531, the intake hole; 54, the cylindrical surface of the vortex chamber; 6, the exhaust valve; 7, the exhaust filter; 71, the static hole; 72, the center axis of the exhaust filter; 8, the static dropper; 81, the dropper hole; 9, the injection capillary; 10, the automatic syringe; 1010, the injection hole; 111, the sensor sealing column; 1110, the sealing through hole; 1120, the sensor hole; 112, the sensor; 1210, the sensor measuring end. DETAILED DESCRIPTION

[0056] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0057] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0058] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0059] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0060] In order to achieve a more efficient and low-pollution engine, technical measures such as high injection pressure, high boost pressure, and high back pressure are widely used. It is not a low-probability phenomenon that the temperature and back pressure in the cylinder are close to and exceed the critical point of the fuel, making transcritical / supercritical spray mixing an unavoidable issue for the engine. Under critical conditions, the density of the liquid phase is significantly reduced, and the gas-liquid interface is difficult to identify. Instead, it is replaced by a gas-liquid two-phase mixing layer mainly controlled by the diffusion process. The appearance of this mixing layer is attributed to the disappearance of the liquid surface tension and the increase in the thickness of the gas-liquid interface. Therefore, the disintegration of the liquid jet and the formation of the mixture are no longer controlled by surface tension and aerodynamic instability, but are controlled by the turbulent diffusion process. At this time, a slight disturbance at the gas-liquid interface can have a significant impact on the diffusion process of the fuel.

[0061] For a long time, the research on transcritical / supercritical spray has been mainly focused on three aspects. The first is the evaporation characteristics of a single droplet under transcritical / supercritical conditions; the second is the state equation of real fluids and the calculation method of thermophysical properties and transport coefficients under transcritical / supercritical conditions; the third is the stability of the transcritical / supercritical jet mixing layer and its evolution process. The existing experimental methods, such as the main work in constant volume combustion bombs, are to study the jet conditions of the spray, which can provide experimental data for the second point mentioned above. However, because the constant volume combustion bomb can only ensure that the flow field environment remains approximately static relative to the dynamic process of the spray, the weak airflow disturbance caused by temperature transfer is difficult to control and measure, which will cause large errors in the data results due to the characteristics of transcritical / supercritical spray.

[0062] Weak airflow disturbances are difficult to observe and control, but if an obviously observable airflow environment is artificially provided, the flow field parameters of the airflow can be observed, and the airflow disturbances caused by chance can also be predicted and controlled. In this way, the errors and unknowns in the research results caused by the uncontrollable and unmeasurable weak airflow disturbances determined by the disappearance of liquid surface tension and the increase of gas-liquid interface thickness under transcritical / supercritical conditions can be reduced, and the evaporation characteristics of a single droplet under transcritical / supercritical conditions can be studied in an environment where the flow field parameters are known; at the same time, because the static dropper and observation column in the equipment provide static and dynamic flow field environments respectively, the comparison of the motion state of the fuel droplet in the two can study the stability and evolution process of the transcritical / supercritical jet mixing layer.

[0063] like Figure 1 and Figure 2 As shown, a droplet evaporation test bench with known flow field parameters is characterized in that it includes an observation column 1, which is tightly connected to the vortex chamber 5 through an air intake filter tube 2, a transverse rectifying net 3, and an annular rectifying net 4. The exhaust valve 6 is installed in the vent hole 521 of the vortex chamber 5. The observation column 1 is tightly connected to the exhaust filter 7. The static dropper 8 is installed in the static hole 71 in the center of the exhaust filter 7. One end of the injection tube 9 is connected to the injection hole 1010 of the automatic injector 10, and the other end is connected to the dropper hole 81 of the static dropper 8. A plurality of sensor sealing columns 111 are installed in the sealing groove 11 on the observation column 1, and the sensor 112 is installed in the sensor hole 1120 of the sensor sealing column 111.

[0064] like Figure 3 , Figure 4 and Figure 5, the vortex chamber 5 is a hollow cylinder with a circular opening on the top. An air intake column 53 with a square cross section is arranged along the tangent direction of the cylinder in the vortex chamber 5. An air intake hole 531 with a square cross section is arranged in the air intake column 53. The inner wall of the air intake hole 531 is also tangent to the inner wall of the cylindrical surface of the vortex chamber 5. A certain mass flow rate of air enters the vortex chamber 5 from the air intake hole 531. In order to ultimately provide an orderly and controllable flow field environment in the observation column, the airflow is first allowed to form a preliminary ordered state, i.e., a vortex, in the vortex chamber 5. There is a cylinder at the bottom center of the vortex chamber 5, which is an air release column 52. A through hole is arranged in the center of the air release column 52, which is an air release hole 521. As Figure 6 As shown, the exhaust valve 6 is a product that has the function of controlling the interruption of air flow and the speed of air flow. The exhaust valve 6 is just placed in the exhaust hole 521 in the center of the exhaust column 52 of the vortex chamber 5. The exhaust valve 6 can release a certain mass flow of air out of the vortex chamber 5, thereby controlling the mass flow of air that finally enters the observation column 1.

[0065] like Figure 7 , Figure 8 and Fig. 9 As shown, the annular rectifying net 4 is a hemispherical thin plate with an annular plane plate at the bottom. Looking down at the annular rectifying net 4, its grid is arranged to be annularly distributed. The eddy velocity formed in the vortex chamber 5 presents a radially uneven distribution characteristic: the closer to the outside air velocity, the greater the air velocity, and the closer to the inside air velocity, the smaller the air velocity. This is also the reason why the venting column 52 is arranged at the bottom center of the vortex chamber 5, because the air velocity in the center is the smallest, and the air can be released stably without affecting the movement of the vortex. The central axis of the annular rectifying net 4 is coaxially placed with the central axis of the vortex chamber 5, the hemispherical thin plate protrudes upward, and the annular plane plate of the annular rectifying net 4 is close to the top plane of the vortex chamber 5. Since the closer to the outside in the vortex chamber 5, the greater the flow velocity, the grid of the annular rectifying net 4 is arranged to be annularly distributed and hemispherical, so that the flow with a large flow velocity first contacts the rectifying net at the periphery and changes the velocity distribution, and the flow with a small flow velocity contacts the rectifying net at the center last, thereby forming a flow field with uniform velocity distribution along the axial direction.

[0066] like Fig.10 , Fig.11 and Fig.12As shown, the transverse rectifying net 3 is a hemispherical thin plate with an annular plane plate at the bottom. Looking down at the transverse rectifying net 3, its grids are arranged to be parallel to each other in the transverse distribution. The central axis of the transverse rectifying net 3 is coaxially placed with the central axis of the vortex chamber 5, the hemispherical thin plate protrudes upward, and the annular plane plate of the transverse rectifying net 3 is close to the annular plane plate of the annular rectifying net 4. The airflow flowing out of the annular rectifying net 4 has a uniform velocity distribution in the axial direction, but a chaotic velocity distribution in the horizontal direction. Because the closer the vortex is to the periphery, the greater the velocity, the closer the airflow flowing out of the annular rectifying net 4 is to the periphery, the more chaotic the velocity, so the transverse rectifying net 3 is arranged to be hemispherical and the grids are parallel to each other in the transverse distribution. The more chaotic the airflow is, the earlier it contacts the transverse rectifying net 3, and the earlier and more strongly the vortex component in the airflow can be eliminated, so that the airflow flowing out of the transverse rectifying net 3 is also uniformly distributed in the horizontal direction.

[0067] like Fig.13 , Fig.14 and Fig.15 As shown, the air intake filter tube 2 is a hollow cylinder with an open bottom circular surface and parallel horizontally distributed grids on the top circular surface. The central axis of the air intake filter tube 2 is coaxially placed with the central axis of the vortex chamber 5, and the bottom circular surface of the air intake filter tube 2 is in close contact with the annular plane plate of the horizontal rectifying net 3. The airflow flowing out of the horizontal rectifying net 3 is further stabilized in the air intake filter tube 2. The closer to the periphery, the longer the airflow is stabilized. Finally, it is further filtered in the horizontally distributed grids, so that the airflow finally entering the observation column 1 can remain uniform and stable in all directions.

[0068] The airflow flowing out of the air inlet filter tube 2 and entering the observation column 1 is evenly and stably distributed in all directions on the same horizontal plane, eliminating airflow disturbances to the greatest extent. Fig.16 , Fig.17 and Fig.18 As shown, the observation column 1 is a transparent hollow cylinder with circular openings on the upper and lower sides. A longitudinal square gap is opened on the annular cylindrical surface as a sealing groove 11, and longitudinal long square sealing bosses 13 are arranged on the cylindrical surfaces on both sides of the sealing groove 11. Sealing screw holes 131 are evenly arranged longitudinally on the sealing bosses 13 on both sides, and the positions of the sealing screw holes 131 on the sealing bosses 13 on both sides correspond horizontally to each other. The central axis of the observation column 1 is coaxial with the central axis of the vortex chamber 5, and the bottom surface of the observation column 1 is in close contact with the top surface of the air intake filter tube 2. Fig.19 and Fig. 20As shown, the sensor 112 sealing column 111 is a column with a "convex" cross section. A through hole is set in the center of the sensor 112 sealing column 111 along its horizontal direction as the sensor 112 hole 1120, and through holes are set in the two sides of the sensor 112 sealing column 111 along its horizontal direction as sealing through holes 1110. A plurality of sensor 112 sealing columns 111 are just placed in the sealing through groove 11, and are arranged horizontally and longitudinally from top to bottom. Bolts pass through the sealing through hole 1110 and the sealing screw hole 131 to fasten the sensor 112 sealing column 111 to the observation column 1. Fig.21 As shown, the sensor 112 is a general term for a class of products, including pressure sensors 112, temperature sensors 112, etc., which can measure physical characteristics at corresponding positions in the flow field. The sensor 112 can be just placed in the sensor 112 hole 1120 of the sensor 112 sealing column 111, and the measuring end of the sensor 112 is close to the central axis of the vortex chamber 5. The observation column 1, the sensor 112 sealing column 111 and the sensor 112 realize the sealing of the internal space of the observation column 1. At different positions inside the observation column 1 and near the central axis, the local pressure and temperature are measured by the measuring end of the sensor 112. The local density and velocity can be calculated according to the Clapeyron equation and the Bernoulli equation, and the mass flow rate of the airflow entering the observation column 1 is known. Therefore, the flow field parameters such as pressure, temperature, density and velocity of the airflow near the central axis inside the observation column 1 are all known. In this way, an obviously observable airflow environment can be artificially provided, and the flow field parameters of the airflow can be observed. The accidental airflow disturbances can also be predicted and controlled. The evaporation characteristics of a single droplet under transcritical / supercritical conditions can be studied in an environment where the flow field parameters are known.

[0069] like Fig. 22 , Fig.23 and Fig.24 The exhaust filter 7 is a hollow cylinder with an open bottom circular surface, parallel horizontally distributed grids arranged on the top circular surface, and a through hole arranged in the center of the top circular surface as a static hole 71. The central axis of the exhaust filter 7 is coaxially placed with the central axis of the vortex chamber 5, and the bottom surface of the exhaust filter 7 is close to the top surface of the observation column 1. The airflow passing through the observation column 1 flows out from the exhaust filter 7 in time to avoid unnecessary disturbance caused by airflow accumulation.

[0070] like Fig.25 As shown, the automatic injector 10 is a product, which is composed of an injection pump and a syringe, and has the function of evenly and slowly pushing a liquid of appropriate mass into the injection tube 9. There is an injection hole 1010 on the automatic injector 10. Fig.26 and Fig. 27 As shown, the injection tube 9 is a round tube, and its shape is adapted to the test environment. One end of the injection tube 9 is just placed in the dropper hole 81 on the static dropper 8, and the other end is just placed in the injection hole 1010 on the automatic injector 10. Fig.28 and Fig.29 As shown, the static dropper 8 is a transparent hollow long cylinder with an open bottom circular surface and a through hole set in the center of the top circular surface as a dropper hole 81. The static dropper 8 can be just placed in the static hole 71 on the exhaust filter 7, and the bottom surface of the static dropper 8 coincides with the bottom surface of the exhaust filter 7. A certain mass of fuel is finally dripped into the static dropper 8 from the automatic injector 10 through the injection capillary 9. Since the inside of the static dropper 8 is sealed, it can be considered that the inside of the static dropper 8 is a static gas environment; and when the fuel droplets fall out of the bottom surface of the static dropper 8, this place coincides with the bottom surface of the exhaust filter 7 and begins to be affected by the airflow. The static dropper 8 and the observation column 1 in the device provide static and dynamic flow field environments respectively, so the comparison of the motion state of the fuel droplets in the two can study the stability and evolution process of the transcritical / supercritical jet mixing layer.

[0071] The installation method and function realization process of a droplet evaporation test bench with known flow field parameters of the present invention are as follows:

[0072] The exhaust valve 6 can be just placed in the exhaust hole 521 at the center of the exhaust column 52 of the vortex chamber 5 .

[0073] The central axis of the annular rectifying net 4 is coaxially placed with the central axis of the vortex chamber 5 , the hemispherical thin plate protrudes upward, and the annular plane plate of the annular rectifying net 4 is closely attached to the top plane of the vortex chamber 5 .

[0074] The central axis of the transverse rectifying net 3 is coaxially placed with the central axis of the vortex chamber 5 , the hemispherical thin plate protrudes upward, and the annular plane plate of the transverse rectifying net 3 is closely attached to the annular plane plate of the annular rectifying net 4 .

[0075] The central axis of the air intake filter tube 2 is coaxially placed with the central axis of the vortex chamber 5 , and the bottom circular surface of the air intake filter tube 2 is in close contact with the annular plane plate of the transverse rectifying net 3 .

[0076] The central axis of the observation column 1 is coaxially placed with the central axis of the vortex chamber 5 , and the bottom surface of the observation column 1 is in close contact with the top surface of the air intake filter tube 2 .

[0077] Several sealing columns 111 of sensors 112 are just placed in the sealing grooves 11 and arranged horizontally and longitudinally from top to bottom. Bolts fasten the sealing columns 111 of sensors 112 to the observation column 1 through the sealing holes 1110 and the sealing screw holes 131.

[0078] The sensor 112 can be just placed in the sensor 112 hole 1120 of the sensor 112 sealing column 111. The measuring end of the sensor 112 is close to the central axis of the vortex chamber 5. The observation column 1, the sensor 112 sealing column 111 and the sensor 112 realize the sealing of the internal space of the observation column 1.

[0079] The central axis of the exhaust filter 7 is coaxially placed with the central axis of the vortex chamber 5 , and the bottom surface of the exhaust filter 7 is in close contact with the top surface of the observation column 1 .

[0080] One end of the injection tube 9 is just placed in the dropper hole 81 on the static dropper 8, and the other end is just placed in the injection hole 1010 on the automatic injector 10.

[0081] The static dropper 8 can be just placed in the static hole 71 on the exhaust filter 7, and the bottom surface of the static dropper 8 coincides with the bottom surface of the exhaust filter 7. Thus, the installation of a droplet evaporation test bench with known flow field parameters is completed.

[0082] Air of a certain mass flow rate enters the vortex chamber 5 from the air inlet 531. In order to ultimately provide an orderly and controllable flow field environment in the observation column, the airflow is first allowed to form a preliminary orderly state, namely a vortex, in the vortex chamber 5.

[0083] Because the air velocity in the center of the vortex chamber 5 is the smallest, the air can be released stably without affecting the movement of the vortex, so the air release column 52 and the exhaust valve 6 are arranged in the center of the bottom of the vortex chamber 5. The exhaust valve 6 is a product that has the function of controlling the interruption of air flow and the flow velocity of air flow. The exhaust valve 6 can release a certain mass flow of air out of the vortex chamber 5, thereby controlling the mass flow of air that finally enters the observation column 1.

[0084] The eddy velocity formed in the vortex chamber 5 presents a radially uneven distribution characteristic: the closer to the outside air flow rate, the greater the air flow rate, and the closer to the inside air flow rate, the smaller the air flow rate, so the grid of the annular rectifying net 4 is arranged to be annularly distributed and hemispherical, so that the flow with a large velocity first contacts the rectifying net at the periphery and changes the velocity distribution, and the flow with a small velocity contacts the rectifying net at the center last, thereby forming a flow field with uniform velocity distribution along the axial direction.

[0085] The velocity of the airflow flowing out of the annular rectifying net 4 is uniformly distributed in the axial direction, but the velocity distribution in the horizontal direction is chaotic. Since the closer the vortex is to the periphery, the greater the velocity, the closer the airflow flowing out of the annular rectifying net 4 is to the periphery, the more chaotic the velocity is. Therefore, the transverse rectifying net 3 is configured to be hemispherical and the grids are parallel to each other in the transverse distribution. The more chaotic the airflow is, the earlier it contacts the transverse rectifying net 3, and the earlier and more strongly the vortex component in the airflow can be eliminated, so that the airflow flowing out of the transverse rectifying net 3 is also uniformly distributed in the horizontal direction.

[0086] The airflow flowing out of the transverse rectifying net 3 is further stabilized in the air inlet filter tube 2. The closer the airflow is to the periphery, the longer the airflow is stabilized. Finally, it is further filtered in the transversely distributed grid, so that the airflow finally entering the observation column 1 can remain uniform and stable in all directions.

[0087] The airflow flowing out of the air inlet filter tube 2 and entering the observation column 1 is evenly and stably distributed in all directions of the same horizontal plane, eliminating airflow disturbances to the greatest extent. The sensor 112 is a general term for a class of products, including pressure sensors 112, temperature sensors 112, etc., which can measure the physical characteristics of corresponding positions in the flow field. At different positions inside the observation column 1 and near the central axis, the local pressure and temperature are measured by the measuring end of the sensor 112, and the mass flow rate of the airflow entering the observation column 1 is known. Then, according to the Clapeyron equation and the Bernoulli equation, the local density and velocity can be calculated. Therefore, the flow field parameters such as pressure, temperature, density and velocity of the airflow near the central axis inside the observation column 1 are all known. In this way, an obviously observable airflow environment can be artificially provided, and the flow field parameters of the airflow can be observed at this time, and the airflow disturbance caused by chance can also be predicted and controlled. The evaporation characteristics of a single droplet under transcritical / supercritical conditions can be studied in an environment where the flow field parameters are all known.

[0088] The airflow passing through the observation column 1 flows out from the exhaust filter 7 in time to avoid unnecessary disturbance caused by airflow accumulation.

[0089] The automatic injector 10 is a product, which consists of an injection pump and an injector, and has the function of uniformly and slowly pushing an appropriate mass of liquid into the injection capillary 9. A certain mass of fuel is finally dripped from the automatic injector 10 through the injection capillary 9 into the static dropper 8. Since the static dropper 8 is sealed inside, it can be considered that the inside of the static dropper 8 is a static gas environment; and when the fuel droplets fall out of the bottom surface of the static dropper 8, this place coincides with the bottom surface of the exhaust filter 7 and begins to be affected by the airflow. The static dropper 8 and the observation column 1 in the equipment provide static and dynamic flow field environments respectively, so the comparison of the motion state of the fuel droplets in the two can study the stability and evolution process of the transcritical / supercritical jet mixing layer. So far, the description of the functional realization process of a droplet evaporation test bench with known flow field parameters has been completed.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A droplet evaporation test bench with known flow field parameters, characterized in that: It includes an observation column, an air inlet filter tube, a transverse rectifying net, an annular rectifying net, a vortex chamber, an exhaust valve, an exhaust filter, a static dropper, an injection capillary and an automatic injector; One end of the observation column is tightly connected to the vortex chamber through an air inlet filter tube, a transverse rectifying net, and an annular rectifying net; the exhaust valve is installed in the exhaust hole of the vortex chamber; The other end of the observation column is tightly connected to the exhaust filter, the static dropper is installed in the static hole of the exhaust filter, one end of the injection tube is connected to the injection hole of the automatic syringe, and the other end is connected to the dropper hole of the static dropper, several sensor sealing columns are installed in the sealing grooves on the observation column, and the sensors are installed in the sensor holes of the sensor sealing columns.

2. A droplet evaporation test bench with known flow field parameters according to claim 1, characterized in that: The vortex chamber is in the shape of a hollow cylinder with an open circular surface at the top; a cylinder is provided in the center of the bottom of the vortex chamber, which is a venting column, and a through hole is provided in the center of the venting column as the venting hole; an air intake column with a square cross-section is provided in the vortex chamber along the tangent direction of the cylinder, and an air intake hole with a square cross-section is provided in the air intake column, and the inner wall of the air intake hole is also tangent to the inner wall of the cylindrical surface of the vortex chamber.

3. A droplet evaporation test bench with known flow field parameters according to claim 1, characterized in that: The annular rectifying net is a hemispherical thin plate, and an annular flat plate is provided at the bottom; the central axis of the annular rectifying net is coaxially placed with the central axis of the vortex chamber, the hemispherical thin plate of the annular rectifying net protrudes upward, and the annular flat plate of the annular rectifying net is closely attached to the top plane of the vortex chamber; The transverse rectifying net is a hemispherical thin plate with an annular plane plate at the bottom; its grids are arranged to be parallel to each other in a transverse distribution; the central axis of the transverse rectifying net is coaxially placed with the central axis of the vortex chamber, the hemispherical thin plate protrudes upward, and the annular plane plate of the transverse rectifying net is closely attached to the annular plane plate of the annular rectifying net; The air intake filter tube is a hollow cylinder with an open bottom circular surface and parallel horizontally distributed grids arranged on the top circular surface; the central axis of the air intake filter tube is coaxially placed with the central axis of the vortex chamber, and the bottom circular surface of the air intake filter tube is in close contact with the horizontal rectifying net annular plane plate.

4. A droplet evaporation test bench with known flow field parameters according to claim 1, characterized in that: The observation column is a transparent hollow cylinder with circular openings on the upper and lower sides; a longitudinal square gap is opened on the annular cylindrical surface as a sealing groove, and longitudinal long square sealing bosses are arranged on the cylindrical surfaces on both sides of the sealing groove. Sealing screw holes are evenly arranged longitudinally on the sealing bosses on both sides, and the positions of the sealing screw holes on the sealing bosses on both sides correspond horizontally to each other; the central axis of the observation column is coaxially placed with the central axis of the vortex chamber, and the bottom surface of the observation column is close to the top surface of the air intake filter tube.

5. The droplet evaporation test bench with known flow field parameters according to claim 1, characterized in that: The exhaust filter is a hollow cylinder with an open bottom circular surface, parallel horizontally distributed grids arranged on the top circular surface, and a through hole arranged in the center of the top circular surface as a static hole; the central axis of the exhaust filter is coaxially placed with the central axis of the vortex chamber, and the bottom surface of the exhaust filter is close to the top surface of the observation column.

6. The droplet evaporation test bench with known flow field parameters according to claim 1, characterized in that: The static dropper is a transparent hollow long cylinder with an opening on the bottom circular surface and a through hole in the center of the top circular surface as a dropper hole; the static dropper can be placed in the static hole on the exhaust filter, and the bottom surface of the static dropper coincides with the bottom surface of the exhaust filter.

7. The droplet evaporation test bench with known flow field parameters according to claim 1, characterized in that: The automatic syringe is a product consisting of an injection pump and a syringe, and has the function of evenly and slowly pushing a liquid of appropriate mass into an injection tube. There is an injection hole on the automatic syringe.

8. A droplet evaporation test bench with known flow field parameters according to claim 7, characterized in that: The injection capillary is a round tube, and its shape is adapted to the test environment; one end of the injection capillary is placed in the dropper hole on the static dropper, and the other end is placed in the injection hole on the automatic injector.

9. The droplet evaporation test bench with known flow field parameters according to claim 1, characterized in that: The sensor sealing column is a column with a "convex"-shaped cross-section. A through hole is arranged in the center of the sensor sealing column along its horizontal direction as a sensor hole, and through holes are arranged in the horizontal direction on both sides of the sensor sealing column along its horizontal direction as sealing through holes. Several sensor sealing columns are placed in the sealing through groove and arranged horizontally and longitudinally from top to bottom. Bolts are used to fasten the sensor sealing columns to the observation column through the sealing through holes and the sealing screw holes.

10. A droplet evaporation test bench with known flow field parameters according to claim 9, characterized in that: The sensor includes a pressure sensor and a temperature sensor, which can measure the physical characteristics at the corresponding position in the flow field; the sensor can be placed in the sensor hole of the sensor sealing column, and the measuring end of the sensor is close to the central axis of the vortex chamber. The observation column, the sensor sealing column and the sensor realize the sealing of the internal space of the observation column.

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