A steady flow droplet evaporation test bench

Abstract

The present application relates to a kind of steady flow liquid drop evaporation test bench, including primary steady flow cylinder, primary steady flow cylinder is bolted with cylinder through secondary steady flow cylinder and tertiary steady flow cylinder;Two end covers are bolted with cylinder on the end cover plane of cylinder, optical glass is installed in end cover optical glass groove and cylinder optical glass groove;Heater is installed in the heater groove on the inner wall of cylinder;Automatic injector is installed on the injection plane above cylinder, and injection capillary tube installed on automatic injector extends into cylinder through sealing plug;Sealing plug is installed in the sealing plug mounting hole above cylinder;Air inlet valve and exhaust valve are installed in air inlet valve hole and exhaust valve hole on cylinder respectively.The present application makes fuel droplet and environmental gas fully interact, and makes fuel droplet even in environmental gas free fall, and will not be randomly changed trajectory and shape by disorderly airflow because of lighter mass, improve the accuracy of test result.

Description

Technical Field

[0001] This invention belongs to the field of engine-related testing technology, specifically relating to a droplet evaporation test bench with stable flow. Background Technology

[0002] In the operation of a diesel engine, the in-cylinder fuel spray combustion is the most critical stage. Since the advent and development of diesel engines in modern times, the pressure and temperature inside the cylinder have not exceeded the critical point of the fuel (properties). Therefore, current theoretical research on in-cylinder fuel spray is limited to subcritical conditions, where the interface between the fuel liquid and gas is clear. However, with increasingly stringent global environmental regulations, researchers worldwide have continuously strived to develop highly efficient and low-emission engines. Consequently, technologies such as high injection pressure, high back pressure, and high back temperature are widely used in modern diesel engines. This causes the injected fuel to approach and exceed its critical point, entering a transcritical / supercritical state. In the transcritical / supercritical state, the liquid-gas interface no longer exists; in effect, there is no distinction between liquid and gas. The fuel injection and fuel / air mixture formation processes have extremely complex mechanisms completely different from those in subcritical conditions, and currently, our understanding of these mechanisms is very superficial.

[0003] Since the dynamic characteristics of spray are essentially the statistical sum of the evaporation characteristics of a large number of individual droplets, a thorough understanding of the evaporation characteristics of single droplets under transcritical / supercritical conditions is a necessary prerequisite for studying the mechanism of transcritical / supercritical spray. Under transcritical / supercritical conditions, the droplet evaporation process exhibits many characteristics different from those under subcritical conditions. One of the most important is the need to consider intermolecular interactions. Simultaneously, under transcritical / supercritical conditions, transient effects become significant, the thermophysical properties of the fluid become increasingly transient, and the thermodynamic properties of both the gas and liquid phases change significantly with environmental conditions. However, current experiments often employ the method of observing fuel droplets dropped onto a glass slide. This method prevents the droplets from fully interacting with the air, and the obstruction caused by the glass slide greatly diminishes the transient effects of the droplet evaporation process, resulting in inaccurate and uncertain studies of the fuel droplet evaporation process under transcritical / supercritical conditions. Summary of the Invention

[0004] This invention provides a stable-flow droplet evaporation test bench. The technical problem to be solved is to address the problems of inaccurate and uncertain research on the evaporation mechanism of fuel droplets under transcritical / supercritical conditions caused by traditional droplet evaporation research methods. It can study the transient whole process of the interaction between fuel droplets with different initial diameters and masses and ambient gases in different states.

[0005] To solve the above technical problems, the present invention provides a droplet evaporation test bench with stable flow, characterized in that it includes a cylinder body 2, a primary flow stabilizer 5, a secondary flow stabilizer 4, and a tertiary flow stabilizer 3, which are nested from the inside out and fixedly connected to the cylinder body 2; two end caps are fixed to the left and right ends of the cylinder body 2 respectively; optical glass 11 is installed in the optical glass groove 62 of the end cap and the optical glass groove 26 of the cylinder body; a heater 10 is installed in the heater groove 28 on the inner wall of the cylinder body; an auto-injector 9 is installed on the injection plane 22 above the cylinder body 2; an injection tube 8 installed on the auto-injector 9 extends into the cylinder body 2 through a sealing plug 7; and an inlet valve 12 and an exhaust valve 13 are installed in the inlet valve hole 211 and the exhaust valve hole 212 on the cylinder body 2 respectively.

[0006] Beneficial effects:

[0007] 1) This invention adopts the method of allowing fuel droplets to fall freely in a transcritical / supercritical environment, so that the fuel droplets can fully interact with the ambient gas. The initial diameter of the fuel droplets is controlled by changing the diameter of the injection tube, and the mass of the fuel droplets is controlled by the auto-injector. This allows for the study of the transient process of the interaction between fuel droplets with different initial diameters and masses and ambient gases in different states.

[0008] 2) At the same time, a multi-stage flow stabilizer is set up to regulate the disordered airflow inside the cylinder, so that even if the fuel droplets fall freely in the ambient gas, they will not have their trajectory and shape changed by the disordered airflow due to their light mass, thus making them easier to observe and improving the accuracy of the test results.

[0009] 3) This test bench has a simple structure, is easy to manufacture and install, and allows for easy replacement of parts, which improves the simplicity and speed of the test, reduces economic costs and the time cost of operation during the test; at the same time, this test bench takes into account various interactions between airflow and single droplets, which improves the accuracy and universality of the test results. Attached Figure Description

[0010] Figure 1 An oblique view of the heater of a droplet evaporation test bench with stable flow according to the present invention;

[0011] Figure 2 The image shows a perspective view of the inlet valve and exhaust valve of a droplet evaporation test bench with stable flow according to the present invention.

[0012] Figure 3 This is an overall front sectional view of a droplet evaporation test bench with stable flow according to the present invention;

[0013] Figure 4 This is a left sectional view of the overall flow-stabilized droplet evaporation test bench according to the present invention.

[0014] Figure 5 This is a front upper right oblique view of the cylinder body of a droplet evaporation test bench with stable flow according to the present invention;

[0015] Figure 6 This is a lower right oblique view of the cylinder body of a droplet evaporation test bench with stable flow according to the present invention;

[0016] Figure 7 This is a front sectional view of the cylinder of a droplet evaporation test bench with stable flow according to the present invention.

[0017] Figure 8 This is a left sectional view of the cylinder of a droplet evaporation test bench with stable flow according to the present invention.

[0018] Figure 9 This is a front upper right oblique view of the three-stage flow stabilizing cylinder of a droplet evaporation test bench with stable flow according to the present invention;

[0019] Figure 10 This is a lower right oblique view of the three-stage flow stabilizer cylinder of a droplet evaporation test bench with stable flow according to the present invention;

[0020] Figure 11 This is a front cross-sectional view of the three-stage flow stabilizer of a droplet evaporation test bench with stable flow according to the present invention.

[0021] Figure 12 This is a left sectional view of the three-stage flow-stabilizing cylinder of a droplet evaporation test bench with stable flow according to the present invention;

[0022] Figure 13 This is a front upper right oblique view of the secondary flow stabilizing cylinder of a droplet evaporation test bench with stable flow according to the present invention;

[0023] Figure 14 This is a lower right oblique view of the secondary flow stabilizing cylinder of a droplet evaporation test bench with stable flow according to the present invention;

[0024] Figure 15 This is a front cross-sectional view of the secondary flow stabilizing cylinder of a droplet evaporation test bench with stable flow according to the present invention;

[0025] Figure 16 This is a left sectional view of the secondary flow stabilizing cylinder of a droplet evaporation test bench with stable flow according to the present invention;

[0026] Figure 17 This is a front upper right oblique view of the primary flow stabilizer cylinder of a droplet evaporation test bench with stable flow according to the present invention;

[0027] Figure 18 This is a lower right oblique view of the first-stage flow stabilizer of a droplet evaporation test bench according to the present invention.

[0028] Figure 19 This is a front cross-sectional view of the primary flow stabilizer of a droplet evaporation test bench according to the present invention.

[0029] Figure 20 This is a left sectional view of the primary flow stabilizer cylinder of a droplet evaporation test bench with stable flow according to the present invention;

[0030] Figure 21 This is a top right oblique view of the end cap of a droplet evaporation test bench with stable flow according to the present invention.

[0031] Figure 22 This is a lower left oblique view of the end cap of a droplet evaporation test bench with stable flow according to the present invention.

[0032] Figure 23 This is a front sectional view of the end cap of a droplet evaporation test bench with stable flow according to the present invention.

[0033] Figure 24 An optical glass perspective view of a droplet evaporation test stage capable of stable flow as described in this invention;

[0034] Figure 25 This is a schematic diagram of the optical path of a droplet evaporation test stage with stable flow according to the present invention;

[0035] Figure 26 A perspective view of the sealing plug of a droplet evaporation test bench with stable flow according to the present invention;

[0036] Figure 27 An oblique view of the automatic injector of the droplet evaporation test bench with stable flow according to the present invention;

[0037] Figure 28 This is a perspective view of the injection capillary of a droplet evaporation test bench with stable flow according to the present invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 2-Cylinder block; 21-Spherical inner cavity; 211-Intake valve hole; 212-Exhaust valve hole; 22-Injection plane; 23-Sealing plug mounting hole; 24-End cap plane; 25-End cap fixing screw hole; 26-Cylinder block optical glass groove; 27-Cylinder block optical observation hole; 28-Heater groove; 29-Stabilizer mounting groove; 291-Third-stage stabilizer mounting hole; 292-First-stage stabilizer mounting screw hole; 293-Second-stage stabilizer mounting screw hole; 294-Third-stage stabilizer mounting screw hole; 3-Third-stage stabilizer; 31-Third-stage stabilizer body; 311-Third-stage stabilizer hole; 32-Third-stage fixing plate; 321-Second-stage stabilizer positioning countersunk hole; 322-First-stage through hole; 323-Second-stage through hole; 324-Third-stage stabilizer mounting through hole; 325-Second-stage stabilizer mounting hole 4-Secondary flow stabilizer; 41-Secondary flow stabilizer body; 411-Secondary flow stabilizer hole; 42-Secondary fixing plate; 421-First-stage flow stabilizer positioning countersunk hole; 422-First-stage transition through hole; 423-Secondary flow stabilizer mounting through hole; 424-First-stage flow stabilizer mounting hole; 5-First-stage flow stabilizer; 51-First-stage flow stabilizer body; 511-First-stage flow stabilizer hole; 52-First-stage fixing plate; 521-First-stage flow stabilizer mounting through hole; 6-End cap; 61-End cap fixing through hole; 62-End cap optical glass groove; 63-End cap observation hole; 7-Sealing plug; 71-Sealing plug injection through hole; 8-Injection tube; 9-Automatic injector; 91-Injection tube connector; 10-Heater; 11-Optical glass; 111-Optical path; 12-Inlet valve; 13-Exhaust valve. Detailed Implementation

[0040] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below.

[0041] like Figures 3 to 4 As shown, the present invention proposes a flow-stabilized droplet evaporation test bench, comprising a primary flow stabilizer 5, which is bolted to a cylinder 2 via a secondary flow stabilizer 4 and a tertiary flow stabilizer 3. Two end caps 6 are bolted to the cylinder 2 on the end cap plane 24. Optical glass 11 is installed in the optical glass groove 62 of the end caps and the optical glass groove 26 of the cylinder. A heater 10 is installed in a heater groove 28 on the inner wall of the cylinder. An auto-injector 9 is installed on the injection plane 22 above the cylinder 2, and an injection tube 8 mounted on the auto-injector 9 extends into the cylinder 2 through a sealing plug 7. The sealing plug 7 is installed in a sealing plug mounting hole 23 above the cylinder 2. An inlet valve 12 and an exhaust valve 13 are respectively installed in the inlet valve hole 211 and the exhaust valve hole 212 on the cylinder 2.

[0042] like Figures 5 to 8As shown, the cylinder body 2 is generally spherical, with a spherical inner cavity 21. A plane on its upper part is an injection plane 22, and a circular through hole on the injection plane 22 serves as a sealing plug mounting hole 23. On the left and right sides of the cylinder body 2 are planes that serve as end cap planes 24, with end cap fixing screw holes 25 distributed in a ring around the outer edge of the end cap planes 24. A circular countersunk hole on the end cap plane 24 serves as a cylinder body optical glass groove 26. A rectangular through hole in the cylinder body optical glass groove 26 serves as a cylinder body optical observation hole 27. A horizontal annular groove on the spherical inner cavity 21 serves as a heater groove 28. Below the cylinder body 2 is a flow stabilizer mounting groove 29, which is a circular countersunk hole. A circular through hole on the flow stabilizer mounting groove 29 serves as a three-stage flow stabilizer mounting hole 291. On the stabilizer mounting slot 29, from the third-stage stabilizer mounting hole 291 outwards, there are ring-shaped mounting screw holes for the first-stage stabilizer 292, the second-stage stabilizer 293, and the third-stage stabilizer 294. On the lower front and rear sides of the cylinder block 2, there is a through hole extending into the spherical inner cavity 21 of the cylinder block, which serves as the intake valve hole 211 and the exhaust valve hole 212, respectively.

[0043] like Figures 9 to 12 As shown, the three-stage flow stabilizer 3 consists of an upper three-stage flow stabilizer body 31 and a lower three-stage fixing plate 32. The three-stage flow stabilizer body 31 is cylindrical with a circular cross-section, and rectangular through holes on its left and right sides are three-stage flow stabilizer holes 311. The three-stage fixing plate 32 is disc-shaped, with the three-stage flow stabilizer body 31 fixed in the upper center, and a circular countersunk hole in the lower center serving as a two-stage flow stabilizer positioning countersunk hole 321. Circular through holes are distributed in a ring around the periphery of the three-stage fixing plate 32, from the inside out: a first-stage through hole 322, a second-stage through hole 323, and a three-stage flow stabilizer mounting through hole 324. The two-stage flow stabilizer positioning countersunk hole 321 has a circular through hole in the center, serving as a two-stage flow stabilizer mounting hole 325. The three-stage flow stabilizer body 31 can be inserted into the three-stage flow stabilizer mounting hole 291 on the cylinder body 2. The three-stage fixing plate 32 can also be inserted into the flow stabilizer mounting groove 29 on the cylinder body 2. The bolts pass through the three-stage flow stabilizer mounting through hole 324 and the three-stage flow stabilizer mounting screw hole 294 to securely connect the three-stage flow stabilizer 3 to the cylinder body 2.

[0044] like Figures 13 to 16As shown, the secondary flow stabilizer 4 consists of an upper secondary flow stabilizer body 41 and a lower secondary fixing plate 42. The secondary flow stabilizer body 41 is cylindrical with a circular cross-section, and rectangular through holes on its left and right sides are secondary flow stabilizer holes 411. The secondary fixing plate 42 is disc-shaped, with the secondary flow stabilizer body 41 fixed in the upper center and a circular countersunk hole in the lower center, which is the primary flow stabilizer positioning countersunk hole 421. Circular through holes are distributed in a ring around the periphery of the secondary fixing plate 42, from the inside out: a primary transition through hole 422 and a secondary flow stabilizer mounting through hole 423. The primary flow stabilizer positioning countersunk hole 421 has a circular through hole in the center, which is the primary flow stabilizer mounting hole 424. The secondary flow stabilizer body 41 can be inserted into the secondary flow stabilizer mounting hole 325, and the secondary fixing plate 42 can be inserted into the secondary flow stabilizer positioning countersunk hole 321. The bolts pass through the secondary flow stabilizer mounting through hole 423, the secondary through hole 323 and the secondary flow stabilizer mounting screw hole 293 to securely connect the secondary flow stabilizer 4 to the cylinder body 2.

[0045] like Figures 17 to 20 As shown, the primary flow stabilizer 5 consists of an upper primary flow stabilizer body 51 and a lower primary fixing plate 52. The primary flow stabilizer body 51 is cylindrical with a circular cross-section, and rectangular through holes 511 are distributed on its left and right sides. The primary fixing plate 52 is disc-shaped, with the primary flow stabilizer body 51 fixed at its upper center. Circular through holes 521 are distributed in a ring around the periphery of the primary fixing plate 52. The primary flow stabilizer body 51 can be inserted precisely into the primary flow stabilizer mounting hole 424, and the primary fixing plate 52 can be inserted precisely into the primary flow stabilizer positioning countersunk hole 421. Bolts are used to securely connect the primary flow stabilizer 5 to the cylinder body 2 through the primary flow stabilizer mounting through hole 521, the primary transition through hole 422, the primary through hole 322, and the primary flow stabilizer mounting screw hole 292.

[0046] like Figures 21 to 23 As shown, the end cap 6 is cylindrical in shape, with circular through holes 61 arranged in a ring around its outer edge. A circular countersunk hole on one side serves as the end cap optical glass groove 62. A circular through hole in the center of the end cap 6 serves as the end cap observation hole 63. The end cap 6 rests against the end cap plane 24, making the end cap optical glass groove 62 adjacent to the cylinder body optical glass groove 26. The end cap 6 is fixed to the cylinder body 2 by bolts passing through the end cap fixing through holes 61 and the end cap fixing screw holes 25.

[0047] like Figure 24As shown, the optical glass 11 is a product, a cylinder with appropriate height and diameter, transparent, which can fit perfectly into the end cap optical glass groove 62 and the cylinder optical glass groove 26. The end cap observation hole 63, the optical glass 11, the cylinder optical observation hole 27, the third-stage flow stabilization hole 311, the second-stage flow stabilization hole 411, and the first-stage flow stabilization hole 511 are on the same straight line, and the maximum common area formed by them is the optical path 111 that allows observation of the interior of the test bench from the outside. Figure 25 As shown, objects within the optical path 111 of the test platform can be observed and recorded from outside the test platform.

[0048] like Figure 26 As shown, the sealing plug 7 is a cylindrical solid made of a certain material, which has the functions of heat insulation, sealing and fixing. It has a circular through hole of appropriate diameter in the center, which is the sealing plug injection through hole 71. The sealing plug 7 fits perfectly into the sealing plug mounting hole 23 on the cylinder body 2.

[0049] like Figure 27 As shown, the autoinjector 9 is a product, simplified in the figure, consisting of an injection pump and a syringe, which has the function of uniformly and slowly propelling an appropriate mass of liquid into an injection capillary. The annular interface on the autoinjector 9 is an injection capillary connector 91, which can be connected to injection capillary tubes 8 of different diameters. The autoinjector 9 is mounted on the injection plane 22 on the cylinder 2.

[0050] like Figure 28 As shown, the injection capillary 8 is a tubular part with appropriate internal and external diameters and an appropriate length. In the experiment, an injection capillary with an appropriate inner diameter can be selected, and an appropriate mass can be injected via an automatic injector, thereby determining the initial diameter and mass of the droplet. The outer diameter of the injection capillary 8 is just large enough to extend into the injection port 71 of the sealing plug, and then through the injection port 71 into the first-stage flow-stabilizing cylinder 51 within the spherical inner cavity 21 of the cylinder body. The appropriate length of the injection capillary 8 ensures that one end is within the observable optical path 111. Thus, when a fuel droplet of appropriate diameter and mass falls freely, the transient process during the droplet's descent can be observed and recorded by a camera device installed outside the test bench. To study the evaporation characteristics of a single droplet under transcritical / supercritical conditions, the entire process of the fuel droplet interacting with the static ambient gas relative to the test bench during its descent is crucial for observation and recording. However, the influence of airflow in the moving environment on the trajectory and morphology of the fuel droplet must be avoided in the experiment, as this will affect the mapping of the experimental results to the evaporation mechanism. The primary flow stabilizing orifice 511, the secondary flow stabilizing orifice 411, and the tertiary flow stabilizing orifice 311 regulate the disordered airflow in the environment, thereby constructing an environmental gas that remains static relative to the test bench in the primary flow stabilizing cylinder 51, thus improving the accuracy of the test results.

[0051] like Figure 1 As shown, the heater 10 is an existing product, simplified in the figure, and is a partial annular body with appropriate diameter and height, containing an electric heating wire for heating air. The heater 10 is installed in the heater slot 28 of the cylinder 2.

[0052] like Figure 2 As shown, the intake valve 12 and exhaust valve 13 are both mature products, and are represented by a simple geometric simplification in the figure. They have the function of controlling the airflow interruption and the airflow speed.

[0053] The intake valve 12 and the exhaust valve 13 are respectively installed in the intake valve hole 211 and the exhaust valve hole 212 on the cylinder block 2.

[0054] By controlling the intake and exhaust valves and heating the ambient gas with a heater, an ambient gas with appropriate pressure and temperature can be constructed inside the test bench, thereby creating a transcritical / supercritical environment for fuel droplets.

[0055] The installation method and functional implementation process of the stable-flow droplet evaporation test bench of the present invention are as follows:

[0056] First, the end cap 6 rests against the end cap plane 24, making the end cap optical glass groove 62 adjacent to the cylinder optical glass groove 26. The optical glass 11 is placed into the end cap optical glass groove 62 and the cylinder optical glass groove 26. The end cap 6 is fixed to the cylinder 2 by bolts passing through the end cap fixing through hole 61 and the end cap fixing screw hole 25.

[0057] The third-stage flow stabilizer body 31 can be inserted precisely into the third-stage flow stabilizer mounting hole 291 on the cylinder body 2, and the third-stage fixing plate 32 can also be inserted precisely into the flow stabilizer mounting groove 29 on the cylinder body 2; the second-stage flow stabilizer body 41 can be inserted precisely into the second-stage flow stabilizer mounting hole 325, and the second-stage fixing plate 42 can be inserted precisely into the second-stage flow stabilizer positioning countersunk hole 321; the first-stage flow stabilizer body 51 can be inserted precisely into the first-stage flow stabilizer mounting hole 424, and the first-stage fixing plate 52 can be inserted precisely into the first-stage flow stabilizer positioning countersunk hole 421. The above process ensures that the end cap observation hole 63, optical glass 11, cylinder optical observation hole 27, third-stage flow stabilizer hole 311, second-stage flow stabilizer hole 411, and first-stage flow stabilizer hole 511 are aligned on the same straight line. The maximum common area formed by these components is the optical path 111, which allows observation of the interior of the test bench from the outside. Then, bolts are used to fasten the third-stage flow stabilizer 3 to the cylinder 2 through the third-stage flow stabilizer mounting through hole 324 and the third-stage flow stabilizer mounting screw hole 294. Bolts are used to fasten the second-stage flow stabilizer 4 to the cylinder 2 through the second-stage flow stabilizer mounting through hole 423, the second-stage through hole 323, and the second-stage flow stabilizer mounting screw hole 293. Bolts are used to fasten the first-stage flow stabilizer 5 to the cylinder 2 through the first-stage flow stabilizer mounting through hole 521, the first-stage transition through hole 422, the first-stage through hole 322, and the first-stage flow stabilizer mounting screw hole 292.

[0058] Then, the heater 10 is installed in the heater slot 28 of the cylinder block 2, and the intake valve 12 and the exhaust valve 13 are respectively installed in the intake valve hole 211 and the exhaust valve hole 212 on the cylinder block 2;

[0059] Finally, the sealing plug 7 is precisely inserted into the sealing plug mounting hole 23 on the cylinder 2; the autoinjector 9 is installed on the injection plane 22 on the cylinder 2, and the annular interface on the autoinjector 9 is an injection capillary connector 91, which can be connected to injection capillary tubes 8 of different diameters. The outer diameter of the injection capillary tube 8 is just enough to extend into the injection through hole 71 of the sealing plug, and then through the injection through hole 71 into the first-stage flow-stabilizing cylinder 51 in the spherical inner cavity 21 of the cylinder. The length of the injection capillary tube 8 is appropriate so that one end of it is in the observable optical path 111. This completes the installation of the flow-stabilizing droplet evaporation test bench.

[0060] The heater 10 is a product containing an electric heating wire that can heat air; the intake valve 12 and exhaust valve 13 are both mature products, with the function of controlling the airflow interruption and airflow speed; meanwhile, the sealing plug 7 is a cylindrical solid made of a certain material, with the functions of heat insulation, sealing, and fixation. Thus, by controlling the intake and exhaust valves and heating the ambient gas with the heater, an ambient gas with appropriate pressure and temperature can be constructed inside the test bench, thereby creating a transcritical / supercritical environment for fuel droplets.

[0061] The optical glass 11 is a transparent product. The end cap observation hole 63, the optical glass 11, the cylinder optical observation hole 27, the third-stage flow stabilizing hole 311, the second-stage flow stabilizing hole 411, and the first-stage flow stabilizing hole 511 are all on the same straight line. The largest common area formed by them is the optical path 111, which allows observation of the interior of the test bench from the outside. Anything within the optical path 111 of the test bench can be observed and recorded from the outside of the test bench.

[0062] The autoinjector 9 is a product consisting of an injection pump and a syringe, which functions to uniformly and slowly propel an appropriate mass of liquid into an injection capillary. The annular interface on the autoinjector 9 is the injection capillary connector 91, which can be connected to injection capillary tubes 8 of different diameters. During the experiment, an injection capillary with an appropriate inner diameter can be selected, and an appropriate mass can be injected through the autoinjector, thereby determining the initial diameter and mass of the droplet. The length of the injection capillary 8 is appropriate so that its extended end is within the observable optical path 111. Thus, when a fuel droplet of appropriate diameter and mass falls freely, the transient process during the droplet's descent can be observed and recorded by a camera device mounted outside the test bench.

[0063] To study the evaporation characteristics of single droplets under transcritical / supercritical conditions, the entire process of interaction between the fuel droplet and the ambient gas, which remains static relative to the test platform, during its descent is crucial for observation and recording. However, the influence of the moving airflow on the trajectory and morphology of the fuel droplet must be carefully avoided, as this can affect the mapping of the experimental results to the evaporation mechanism. The primary flow stabilizing orifice 511, secondary flow stabilizing orifice 411, and tertiary flow stabilizing orifice 311 regulate the disordered airflow in the environment, thereby constructing an ambient gas that remains static relative to the test platform within the primary flow stabilizing cylinder 51, thus improving the accuracy of the experimental results.

Claims

1. A droplet evaporation test bench with stable flow capability, characterized in that, The system includes a cylinder (2), a primary flow stabilizer (5), a secondary flow stabilizer (4), and a tertiary flow stabilizer (3). The primary flow stabilizer (5), the secondary flow stabilizer (4), and the tertiary flow stabilizer (3) are nested from the inside out and fixedly connected to the cylinder (2). Two end caps are fixed to the left and right ends of the cylinder (2). Optical glass (11) is installed in the optical glass groove (62) of the end cap and the optical glass groove (26) of the cylinder. A heater (10) is installed in the heater groove (28) on the inner wall of the cylinder. An automatic injector (9) is installed on the injection plane (22) above the cylinder (2). An injection tube (8) installed on the automatic injector (9) extends into the cylinder (2) through a sealing plug (7). An air inlet valve (12) and an air outlet valve (13) are installed in the air inlet valve hole (211) and the air outlet valve hole (212) on the cylinder (2), respectively. There is a circular through hole in the center of the end cap (6), which is the end cap observation hole (63); there is a rectangular through hole in the cylinder optical glass groove (26), which is the cylinder optical observation hole (27); The three-stage flow stabilizer (3) consists of an upper three-stage flow stabilizer body (31) and a lower three-stage fixing plate (32). The rectangular through holes distributed on the left and right sides of the three-stage flow stabilizer body (31) are three-stage flow stabilizer holes (311). The secondary flow stabilizer (4) consists of an upper secondary flow stabilizer body (41) and a lower secondary fixing plate (42); the rectangular through holes distributed on the left and right sides of the secondary flow stabilizer body (41) are secondary flow stabilizer holes (411); The primary flow stabilizer (5) consists of an upper primary flow stabilizer body (51) and a lower primary fixing plate (52); rectangular through holes distributed on the left and right sides of the primary flow stabilizer body (51) are primary flow stabilizer holes (511). The end cap observation hole (63), optical glass (11), cylinder optical observation hole (27), third-stage flow stabilizing hole (311), second-stage flow stabilizing hole (411) and first-stage flow stabilizing hole (511) are on the same straight line, and the maximum common area they form is the optical path (111) from which the internal situation can be observed from the outside.

2. The droplet evaporation test bench with stable flow according to claim 1, characterized in that: The cylinder body (2) is spherical in shape and has a spherical inner cavity (21). There is a plane on the upper part of the cylinder body (22) which is an injection plane (22). There is a circular through hole on the injection plane (22) which is a sealing plug mounting hole (23). There are planes on the left and right sides of the cylinder body (2) which are end cap planes (24). There is a horizontal annular groove on the spherical inner cavity (21) of the cylinder body which is a heater groove (28). There is a flow stabilizer mounting groove (29) at the bottom of the cylinder body (2). On the flow stabilizer mounting groove (29), from the third-stage flow stabilizer mounting hole (291) outward, there are first-stage flow stabilizer mounting screw holes (292), second-stage flow stabilizer mounting screw holes (293) and third-stage flow stabilizer mounting screw holes (294) distributed in a ring. There is a through hole on the lower front and rear sides of the cylinder body (2) that extends into the spherical inner cavity (21) of the cylinder body, which are an intake valve hole (211) and an exhaust valve hole (212).

3. The droplet evaporation test bench with stable flow according to claim 2, characterized in that: The three-stage flow stabilizer cylinder (31) is cylindrical with a circular cross-section. The three-stage fixing plate (32) is disc-shaped, with the three-stage flow stabilizer cylinder (31) fixed at the center of its upper part. Circular countersunk holes are distributed in the center of its lower part, serving as positioning countersunk holes (321) for the two-stage flow stabilizer cylinder. Circular through holes are distributed in a ring around the periphery of the three-stage fixing plate (32), from the inside out: a first-stage through hole (322), a second-stage through hole (323), and a third-stage flow stabilizer cylinder mounting through hole (324). The second-stage flow stabilizer cylinder positioning countersunk holes ( 321) There is a through hole in the middle, which is circular and is the mounting hole (325) for the secondary stabilizer cylinder; the tertiary stabilizer cylinder body (31) can be inserted into the tertiary stabilizer cylinder mounting hole (291) on the cylinder body (2), and the tertiary fixing plate (32) can also be inserted into the stabilizer cylinder mounting groove (29) on the cylinder body (2). The bolts pass through the tertiary stabilizer cylinder mounting through hole (324) and the tertiary stabilizer cylinder mounting screw hole (294) to securely connect the tertiary stabilizer cylinder (3) to the cylinder body (2).

4. The droplet evaporation test bench with stable flow according to claim 3, characterized in that: The secondary flow stabilizer body (41) is cylindrical with a circular cross-section; the secondary fixing plate (42) is disc-shaped, with the secondary flow stabilizer body (41) fixed in the center above and a circular countersunk hole distributed in the center below as the primary flow stabilizer positioning countersunk hole (421); the secondary fixing plate (42) has a circular distribution of circular through holes around its periphery, which are the primary transition through hole (422) and the secondary flow stabilizer installation through hole (423) from the inside out; the primary flow stabilizer positioning countersunk hole (421) has a through hole in the middle, which is circular and is the primary flow stabilizer installation hole (424); the secondary flow stabilizer body (41) can be inserted into the secondary flow stabilizer installation hole (325), and the secondary fixing plate (42) can be inserted into the secondary flow stabilizer positioning countersunk hole (321). The bolts pass through the secondary flow stabilizer installation through hole (423), the secondary through hole (323), and the secondary flow stabilizer installation screw hole (293) to securely connect the secondary flow stabilizer body (4) to the cylinder body (2).

5. The droplet evaporation test bench with stable flow according to claim 4, characterized in that: The first-stage flow stabilizer body (51) is cylindrical with a circular cross-section; the first-stage fixing plate (52) is disc-shaped, with the first-stage flow stabilizer body (51) fixed at the center above it; the first-stage fixing plate (52) has circular through holes distributed around its periphery, which are the first-stage flow stabilizer mounting through holes (521); the first-stage flow stabilizer body (51) can be inserted into the first-stage flow stabilizer mounting hole (424), and the first-stage fixing plate (52) can be inserted into the first-stage flow stabilizer positioning countersunk hole (421). The bolts achieve a tight connection between the first-stage flow stabilizer body (5) and the cylinder body (2) through the first-stage flow stabilizer mounting through hole (521), the first-stage transition through hole (422), the first-stage through hole (322), and the first-stage flow stabilizer mounting screw hole (292).

6. The droplet evaporation test bench with stable flow according to claim 2, characterized in that: The end cap (6) is cylindrical in shape, with circular through holes distributed around its outer edge as end cap fixing through holes (61); a circular countersunk hole is provided on one side as end cap optical glass groove (62); the end cap (6) rests on the end cap plane (24), so that the end cap optical glass groove (62) is adjacent to the cylinder optical glass groove (26), and the end cap (6) is fixed to the cylinder (2) by bolts passing through the end cap fixing through hole (61) and the end cap fixing screw hole (25).

7. The droplet evaporation test bench with stable flow according to claim 1, characterized in that: The optical glass (11) is a transparent cylindrical structure.

8. The droplet evaporation test bench with stable flow according to claim 1, characterized in that: The sealing plug (7) is a cylindrical solid with a through hole in the center, which is the injection through hole (71) of the sealing plug.

9. A droplet evaporation test bench with stable flow according to claim 7, characterized in that: The injection tube (8) is a tubular part. The outer diameter of the injection tube (8) is just able to extend into the injection hole (71) of the sealing plug and into the spherical inner cavity (21) of the cylinder body. The length of the injection tube (8) is appropriate so that one end of it is in the observable optical path (111). The annular interface on the automatic injector (9) is the injection tube connector (91), which is connected to injection tubes (8) of different diameters.

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