A spatially staggered liquid film cooling structure and its flow rate calculation method

Abstract

This invention relates to a combustion chamber cooling device and a method for calculating coolant flow rate, specifically to a spatially staggered liquid film cooling structure and its flow rate calculation method. It addresses the technical problem that existing propulsion systems, while maintaining comprehensive performance requirements such as the specific impulse of the attitude and orbit control thrust chamber, struggle to meet the cooling matching requirements across the entire combustion chamber area with liquid film cooling. The spatially staggered liquid film cooling structure includes an injector and a combustion chamber matched to the injector. Multiple wall-impact cooling holes are provided on the edge area of ​​the injector's injection surface. These wall-impact cooling holes include a first wall-impact cooling hole and a second wall-impact cooling hole. The first wall-impact cooling hole is used to cool the converging section and throat of the combustion chamber; the second wall-impact cooling hole is used to cool the cylindrical section of the combustion chamber. The first and second wall-impact cooling holes on adjacent circumferences are staggered along the circumferential direction of the injection surface.

Description

Technical Field

[0001] This invention relates to a combustion chamber cooling device and a method for calculating coolant flow rate, specifically to a spatially staggered liquid film cooling structure and its flow rate calculation method. Background Technology

[0002] The combustion gas temperature in the central area of ​​the attitude and orbit control thrust chamber reaches over 3000℃. Therefore, the cooling design of the combustion chamber walls is crucial for the reliable operation of the thrust chamber. Liquid film cooling is one of the commonly used cooling methods for attitude and orbit control thrust chambers. Its working principle involves injecting propellant through an injector onto the inner wall of the combustion chamber, forming a protective layer with an extremely low liquid / gas film mixture near the wall. This reduces the direct erosion of the combustion chamber substrate by the high-temperature, oxygen-rich combustion gas, as well as convective and radiative heat transfer, thereby lowering the combustion chamber wall temperature and reducing the oxidative erosion of the combustion chamber wall by the combustion gas, thus meeting the operational requirements of the attitude and orbit control thrust chamber.

[0003] The heat flux density varies in different regions of the combustion chamber, such as the cylindrical section, converging section, and throat. The atomization, mixing, and combustion completeness of the propellant also differ in these regions, thus affecting the cooling requirements of the combustion chamber walls. The selection of coolant parameters and the structural arrangement both influence the cooling effect on the combustion chamber walls. Inappropriate selection of cooling parameters or an unreasonable cooling structure arrangement may prevent reliable cooling in different regions of the combustion chamber. With the continuous improvement of the comprehensive performance and reliability requirements of propulsion systems for attitude and orbit control thrust chambers, while maintaining the comprehensive performance such as specific impulse, liquid film cooling may not achieve the optimal cooling matching effect across the entire combustion chamber region. Summary of the Invention

[0004] The purpose of this invention is to address the technical problem that existing propulsion systems, while maintaining comprehensive performance requirements such as attitude and orbit control thrust chamber specific impulse, have difficulty meeting the cooling matching requirements of the entire combustion chamber area with liquid film cooling. This invention provides a spatially staggered liquid film cooling structure and its flow rate calculation method.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A spatially staggered liquid film cooling structure includes an injector and a combustion chamber matched with the injector; the combustion chamber includes a cylindrical section, a converging section, and a throat.

[0007] Its special feature is:

[0008] Multiple wall-breaking cooling holes are provided on the edge area of ​​the injection surface of the injector; the wall-breaking cooling holes include a first wall-breaking cooling hole and a second wall-breaking cooling hole;

[0009] The first and second wall-mounted cooling holes are evenly arranged along different circumferences and are alternately distributed on N circumferences from the outside to the inside; the second wall-mounted cooling holes are arranged on the circumference near the center of the injection surface; N is an integer greater than or equal to 1; the first wall-mounted cooling holes are used to cool the convergent section and throat of the combustion chamber;

[0010] The second wall cooling hole is used to cool the cylindrical section of the combustion chamber;

[0011] The first and second wall-cooling holes on adjacent circumferences are staggered along the circumference of the injection surface.

[0012] Furthermore, the angle α between the first wall cooling hole and the inner wall of the combustion chamber is 10° to 30°;

[0013] The angle β between the second wall cooling hole and the inner wall of the combustion chamber is 30° to 60°.

[0014] Furthermore, the inner diameter of the first wall-mounted cooling hole is smaller than the inner diameter of the second wall-mounted cooling hole.

[0015] Furthermore, the method also includes multiple conical process annular grooves disposed on the edge area of ​​the injection surface corresponding to N circumferential positions; the cross-section of the conical process annular grooves is triangular;

[0016] The first wall-breaking cooling hole and the second wall-breaking cooling hole are respectively located on one side of the triangular cross section near the center of the injection surface, and the central axis of the first wall-breaking cooling hole and the central axis of the second wall-breaking cooling hole are both perpendicular to one side of the triangular cross section.

[0017] Furthermore, the angle α between the first wall cooling hole and the inner wall of the combustion chamber is 20°;

[0018] The angle β between the second wall cooling hole and the inner wall of the combustion chamber is 40°.

[0019] Furthermore, the number of the first wall-mounted cooling holes and the second wall-mounted cooling holes are the same.

[0020] Furthermore, N is 2.

[0021] Meanwhile, this invention also provides a method for calculating the flow rate of the aforementioned spatially staggered liquid film cooling structure, the special feature of which is that the flow rate of the wall cooling holes is calculated by the following formula:

[0022]

[0023] In the formula, i represents the type of wall-mounted cooling hole, i=1 represents the first wall-mounted cooling hole, and i=2 represents the second wall-mounted cooling hole;

[0024] qm iThe flow rate of the i-th type of wall-mounted cooling hole is expressed in kg / s.

[0025] Cd i Let be the flow coefficient of the i-th type of wall-mounted cooling hole;

[0026] n i Let be the number of cooling holes for the i-th type of wall impact;

[0027] D i Let be the inner diameter of the i-th type of wall-mounted cooling hole, in meters (m).

[0028] ρ is the density of the coolant in the injector, in kg / m³. 3 ;

[0029] ΔP is the injection pressure drop of the injector, in Pa.

[0030] Furthermore, the coolant flow distribution ratio between the first wall cooling hole and the second wall cooling hole is 2:3.

[0031] Furthermore, the Cd i The value ranges from 0.55 to 0.8.

[0032] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0033] (1) The spatially staggered liquid film cooling structure of the present invention achieves differentiated selection of the flow rate of the two rings of cooling holes through two rings of wall-impact cooling holes (i.e., the first wall-impact cooling hole and the second wall-impact cooling hole). When optimizing the cooling design parameters of the attitude control thrust chamber, the flow rate of the two rings of cooling holes can be selected in a targeted manner according to the different cooling requirements of different sections of the combustion chamber, so as to meet the coolant requirements of different sections of the combustion chamber and achieve the best parameter matching in different areas of the cylindrical section, convergent section and throat of the combustion chamber.

[0034] (2) The present invention provides a spatially staggered liquid film cooling structure, which sets up a cooling hole structure with two different wall impact angles of large and small in the combustion chamber side area. According to the different coolant requirements of the cylindrical section, converging section and throat of the combustion chamber, and the different state of the coolant from the injection surface downstream to the throat, the coolant flow rate can be selected by staggering the two angles of the cooling holes.

[0035] (3) The present invention features a spatially staggered liquid film cooling structure. Two rings of cooling holes with different impact angles (large and small) are machined in the edge area of ​​the injection plate. Both rings have the same number of holes and are evenly distributed in the injection plate edge area. The first impact cooling hole uses a small impact angle of 10°–30° to cool the convergent section and throat of the combustion chamber; the second impact cooling hole uses a large impact angle of 30°–60° to cool the cylindrical section of the combustion chamber. The cooling holes in different rings are staggered, with a single second impact cooling hole positioned between two adjacent first impact cooling holes, forming a staggered spatial structure that ensures more thorough cooling of the combustion chamber.

[0036] (4) The spatially staggered liquid film cooling structure of the present invention has a first ring of wall-impact cooling holes with an angle of 20° and a second ring of wall-impact cooling holes with an angle of 40°. By setting different inner diameters of the first and second wall-impact cooling holes, the coolant flow distribution ratio of the first and second wall-impact cooling holes is differentiated to 2:3. This achieves reliable cooling of different parts of the cylindrical section, convergent section and throat of the combustion chamber of the thrust chamber. Through multiple high-performance model tests, the highest temperature of the combustion chamber is 1300℃, which has a high temperature margin compared with the allowable temperature of the combustion chamber material.

[0037] (5) The flow rate calculation method of the wall-impact cooling holes of the present invention utilizes the differences in axial velocity component and circumferential liquid film spreading width generated on the combustion chamber wall surface after the cooling holes at different angles impact the wall, to provide targeted cooling for different sections of the cylindrical section, converging section, and throat of the combustion chamber. The larger axial velocity component generated by the first wall-impact hole with a small impact angle allows more coolant to move along the combustion chamber wall surface to the converging section and throat of the combustion chamber, thus cooling these areas. The wider circumferential liquid film spreading width and smaller axial velocity component generated by the second wall-impact cooling hole with a large impact angle allow a larger proportion of coolant to remain near the cylindrical section, thus cooling the cylindrical section of the combustion chamber. This method achieves effective protection and reliable cooling for different areas of the cylindrical section, converging section, and throat of the combustion chamber. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of an embodiment of the spatially staggered liquid film cooling structure of the present invention;

[0039] Figure 2 for Figure 1 Sectional view at point AA;

[0040] Figure 3 This is a schematic diagram showing the angle α between the first wall cooling hole and the inner wall of the combustion chamber in an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram of the angle β between the second wall cooling hole and the inner wall of the combustion chamber in an embodiment of the present invention.

[0042] The attached figures are labeled as follows:

[0043] 1-Injector, 2-Combustion chamber, 21-Cylindrical section, 22-Converging section, 23-Throat, 3-Second wall cooling hole, 4-First wall cooling hole. Detailed Implementation

[0044] like Figure 1 , Figure 2 As shown, a spatially staggered liquid film cooling structure includes an injector 1 and a combustion chamber 2 matched with the injector 1. The combustion chamber 2 includes a cylindrical section 21, a converging section 22, and a throat 23. Multiple wall-breaking cooling holes are provided on the edge area of ​​the injection surface of the injector 1. The wall-breaking cooling holes include a first wall-breaking cooling hole 4 and a second wall-breaking cooling hole 3. The first wall-breaking cooling holes 4 and the second wall-breaking cooling holes 3 are uniformly arranged along different circumferences and are alternately distributed on N circumferences from the outside to the inside. The second wall-breaking cooling holes 3 are located on the circumference near the center area of ​​the injection surface. N is an integer greater than or equal to 1. The first wall-breaking cooling holes 4 are used to cool the converging section 22 and the throat 23 of the combustion chamber 2. The second wall-breaking cooling holes 3 are used to cool the cylindrical section 21 of the combustion chamber 2. The first wall-breaking cooling holes 4 and the second wall-breaking cooling holes 3 on adjacent circumferences are staggered along the circumferential direction of the injection surface. The inner diameter of the first wall-breaking cooling hole 4 is smaller than the inner diameter of the second wall-breaking cooling hole 3. In other embodiments, depending on the cooling requirements of the combustion chamber 2, the inner diameter of the first wall cooling hole 4 can be designed to be greater than or equal to the inner diameter of the second wall cooling hole 3.

[0045] A first ring of wall-mounted cooling holes 4 is machined on the outer side of the injection surface (near the inner wall of the combustion chamber 2), and a second ring of wall-mounted cooling holes 3 is machined on the inner side of the injection surface (near the central axis of the injection surface). The number of holes in the first ring and the second ring of wall-mounted cooling holes 3 are the same, and they are evenly staggered along the circumference of the injection surface. The first rings of wall-mounted cooling holes 4 and the second rings of wall-mounted cooling holes 3 are arranged alternately to form a staggered spatial structure.

[0046] like Figure 3 As shown, the impact angle α of the first wall-impact cooling hole 4 (i.e., the angle between the first wall-impact cooling hole 4 and the inner wall of the combustion chamber 2) is relatively small. When the coolant in the injector 1 impacts the wall at a certain injection speed through the first wall-impact cooling hole 4 at a small angle, a narrow circumferential liquid film spreading width and a large axial velocity are generated near the impact point on the wall of the combustion chamber 2. This allows a large proportion of the coolant to move along the wall of the combustion chamber 2 towards the converging section 22 and throat 23 of the combustion chamber 2, thereby effectively protecting and cooling the converging section 22 and throat 23 of the combustion chamber 2. To obtain the best cooling effect, the value of the impact angle α of the first wall-impact cooling hole 4 is in the range of 10° to 30°.

[0047] like Figure 4 As shown, the impact angle β of the second wall-impact cooling hole 3 (i.e., the angle between the second wall-impact cooling hole 3 and the inner wall of the combustion chamber 2) is relatively large. By utilizing the coolant in the injector 1, which impacts the wall at a certain injection speed through the second wall-impact cooling hole 3 at a large angle, a wider circumferential liquid film spreads and a smaller axial velocity is generated near the impact point on the wall of the combustion chamber 2. This allows a larger proportion of coolant to spread and remain near the impact point of the combustion chamber 2, effectively protecting and cooling the cylindrical section 21 of the combustion chamber 2. To obtain the best cooling effect, the impact angle β of the second wall-impact cooling hole 3 is in the range of 30° to 60°.

[0048] Multiple conical process annular grooves corresponding to N circumferential positions are provided on the edge area of ​​the injection surface; the cross-section of the conical process annular grooves is triangular; the first wall-breaking cooling hole 4 and the second wall-breaking cooling hole 3 are respectively set on the side of the corresponding triangular cross-section near the center area of ​​the injection surface, and the central axis of the first wall-breaking cooling hole 4 and the central axis of the second wall-breaking cooling hole 3 are both perpendicular to one side of the triangular cross-section, so as to ensure the perpendicular machining of the first wall-breaking cooling hole 4 and the second wall-breaking cooling hole 3 and improve the machinability of the central axis of the first wall-breaking cooling hole 4 and the second wall-breaking cooling hole 3. Preferably, based on the comprehensive factors of the cooling requirements in different areas of the attitude control thrust chamber combustion chamber 2 and the machinability of the injector 1, the angle α between the first wall-breaking cooling hole 4 and the inner wall of the combustion chamber 2 is 20°, and the angle β between the second wall-breaking cooling hole 3 and the inner wall of the combustion chamber 2 is 40°.

[0049] The working principle of the above embodiments is as follows:

[0050] After the coolant enters the injector 1, it is sprayed out at a certain injection speed along its respective angular direction through the first wall-impact cooling hole 4 and the second wall-impact cooling hole 3. The first wall-impact cooling hole 4 impacts the inner wall of the combustion chamber 2 at a small angle α, generating a large axial velocity near the impact point on the wall of the combustion chamber 2. This allows a large proportion of the coolant to move along the wall of the combustion chamber 2 towards the converging section 22 and the throat 23, effectively protecting and cooling the converging section 22 and the throat 23 of the combustion chamber 2. The second wall-impact hole impacts the wall at a large angle β, generating a wide circumferential liquid film spread and a small axial velocity near the impact point on the wall of the combustion chamber 2. This allows a large proportion of the coolant to spread and remain near the impact point on the wall of the combustion chamber 2, cooling the cylindrical section 21 of the combustion chamber 2. The coolant flow rates of the first wall-mounted cooling hole 4 and the second wall-mounted cooling hole 3 are selected and distributed according to the cooling requirements of different attitude-controlled thrust chambers. The inner diameter of the first wall-mounted cooling hole 4 is smaller than that of the second wall-mounted cooling hole 3. By using the different diameters of the two rings of wall-mounted cooling holes, the coolant flow rate is distributed differently to meet the coolant requirements of different sections of the combustion chamber 2 and achieve the best matching of cooling effects in different sections of the combustion chamber 2.

[0051] Meanwhile, this invention also provides a method for calculating the flow rate of a spatially staggered liquid film cooling structure, wherein the flow rate of the wall-mounted cooling holes is calculated using the following formula:

[0052]

[0053] In the formula, i represents the type of wall-mounted cooling hole, i=1 represents the first wall-mounted cooling hole 4, and i=2 represents the second wall-mounted cooling hole 3;

[0054] qm i The flow rate of the i-th type of wall-mounted cooling hole is expressed in kg / s.

[0055] Cd i Let be the flow coefficient of the i-th type of wall-mounted cooling hole;

[0056] n i Let be the number of cooling holes for the i-th type of wall impact;

[0057] D i Let be the inner diameter of the i-th type of wall-mounted cooling hole, in meters (m).

[0058] ρ is the density of the coolant in injector 1, in kg / m³. 3 ;

[0059] ΔP is the injection pressure drop of injector 1, in Pa.

[0060] In this embodiment, two rings of coolant injection holes are provided, with different orifice diameters; the first ring has an orifice diameter of ΦD1, and the second ring has an orifice diameter of ΦD2. By using different orifice sizes, the flow rates of the two rings of coolant are differentiated. This allows for targeted selection of coolant flow rates based on the varying cooling requirements of different sections of the combustion chamber 2 during the optimization of the attitude control thrust chamber cooling design parameters, achieving optimal parameter matching in different areas of the cylindrical section 21, the converging section 22, and the throat 23 of the combustion chamber 2. i It is a dimensionless parameter, and its value is generally between 0.55 and 0.8. The specific data is obtained through the liquid flow test of injector 1.

[0061] Preferably, the angle of the first ring of wall-impact cooling holes in the thrust chamber is 20°, and the angle of the second ring of wall-impact cooling holes is 40°. By setting different inner diameters for the first ring of wall-impact cooling holes 4 and the second ring of wall-impact cooling holes 3, a 2:3 ratio of coolant flow distribution between the first ring of wall-impact cooling holes 4 and the second ring of wall-impact cooling holes 3 is achieved. This enables reliable cooling of different parts of the cylindrical section 21, the converging section 22 and the throat 23 of the thrust chamber combustion chamber 2. Through multiple high-performance model tests, the highest temperature of the combustion chamber 2 is 1300℃, which has a high temperature margin compared with the allowable temperature of the combustion chamber 2 material.

Claims

1. A spatially staggered liquid film cooling structure, comprising an injector (1) and a combustion chamber (2) matched with the injector (1); the combustion chamber (2) comprises a cylindrical section (21), a converging section (22) and a throat (23); Its features are: The spray nozzle (1) has multiple wall-cooling holes on the spray surface edge area; the wall-cooling holes include a first wall-cooling hole (4) and a second wall-cooling hole (3); The first wall-breaking cooling hole (4) and the second wall-breaking cooling hole (3) are uniformly arranged along different circumferences and are alternately distributed on N circumferences from the outside to the inside; the second wall-breaking cooling hole (3) is set on the circumference near the center area of ​​the injection surface; N is an integer greater than or equal to 1; The first wall cooling hole (4) is used to cool the converging section (22) and throat (23) of the combustion chamber (2); The second wall cooling hole (3) is used to cool the cylindrical section (21) of the combustion chamber (2); The first wall-breaking cooling hole (4) and the second wall-breaking cooling hole (3) on adjacent circumferences are staggered along the circumference of the injection surface; It also includes multiple conical process annular grooves disposed on the edge area of ​​the injection surface, corresponding to N circumferential positions; the cross-section of the conical process annular grooves is triangular; The first wall-cooling hole (4) and the second wall-cooling hole (3) are respectively located on one side of the triangular cross section near the center of the injection surface, and the central axis of the first wall-cooling hole (4) and the central axis of the second wall-cooling hole (3) are both perpendicular to one side of the triangular cross section.

2. The spatially staggered liquid film cooling structure according to claim 1, characterized in that: The angle α between the first wall cooling hole (4) and the inner wall of the combustion chamber (2) is 10° to 30°. The angle β between the second wall cooling hole (3) and the inner wall of the combustion chamber (2) is 30° to 60°.

3. A spatially staggered liquid film cooling structure according to claim 1 or 2, characterized in that: The inner diameter of the first wall cooling hole (4) is smaller than the inner diameter of the second wall cooling hole (3).

4. The spatially staggered liquid film cooling structure according to claim 3, characterized in that: The angle α between the first wall cooling hole (4) and the inner wall of the combustion chamber (2) is 20°; The angle β between the second wall cooling hole (3) and the inner wall of the combustion chamber (2) is 40°.

5. The spatially staggered liquid film cooling structure according to claim 4, characterized in that: The number of the first wall cooling hole (4) and the second wall cooling hole (3) is the same.

6. The spatially staggered liquid film cooling structure according to claim 5, characterized in that: The value of N is 2.

7. A method for calculating the flow rate of a spatially staggered liquid film cooling structure as described in any one of claims 1-6, characterized in that, The flow rate of the wall cooling hole is calculated using the following formula: In the formula, i represents the type of wall-breaking cooling hole, i=1 represents the first wall-breaking cooling hole (4), and i=2 represents the second wall-breaking cooling hole (3); qm i The flow rate of the i-th type of wall-mounted cooling hole is expressed in kg / s. Cd i Let be the flow coefficient of the i-th type of wall-mounted cooling hole; n i Let be the number of cooling holes for the i-th type of wall impact; D i Let be the inner diameter of the i-th type of wall-mounted cooling hole, in meters (m). ρ is the density of the coolant in the injector (1), in kg / m³. 3 ; ΔP is the injection pressure drop of the injector (1), in Pa.

8. The flow rate calculation method for a spatially staggered liquid film cooling structure according to claim 7, characterized in that: The coolant flow distribution ratio between the first wall cooling hole (4) and the second wall cooling hole (3) is 2:

3.

9. The flow rate calculation method for a spatially staggered liquid film cooling structure according to claim 8, characterized in that: The Cd i The value ranges from 0.55 to 0.8.

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