A calculation method and test system for the thrust coefficient of a throat-plug nozzle

Abstract

The present invention provides a method and test system for calculating the thrust coefficient of a throat-bolt nozzle, primarily addressing the problem of accurately measuring the thrust coefficient of a pintle nozzle under different operating conditions. Based on a throat-bolt nozzle test model, the present invention calculates the corresponding thrust coefficient at a specified combustion chamber pressure using the engine equilibrium pressure calculation formula. The test system, employing this method, includes an engine combustion chamber, an ignition device, a servo control system, a sealed connection structure, a static frame, a dynamic frame, a thrust sensor, and a bearing block. During testing, the engine's combustion chamber pressure and throat area can be precisely controlled, resulting in the nozzle thrust coefficient under the desired operating conditions.

Description

Technical Field

[0001] The present invention relates to the field of variable thrust solid rocket engines, and in particular to a method for testing a nozzle thrust coefficient. Background Art

[0002] The throat plug-type solid rocket engine is a widely studied and relatively mature variable thrust engine. It achieves engine thrust adjustment by changing the throat area through the throat plug actuated along the axial direction of the nozzle.

[0003] In engine design, the thrust coefficient of the nozzle is an important performance parameter. For a throat-type nozzle, shock waves may be generated in the nozzle expansion section when the throat is actuated, and the position of the shock wave will change depending on the position of the throat. Therefore, the thrust coefficient formula derived based on one-dimensional isentropic flow is: No longer applicable. The thrust coefficient of the throat plug nozzle is related to the combustion chamber p c , ambient pressure p a , the ratio of nozzle exit area to throat area In addition to the above, it is also related to the flow state of the gas in the nozzle. c , throat area A t It may vary within a large range and the operating conditions are complex. Existing technology cannot accurately measure the thrust coefficient of the pintle nozzle under different operating conditions. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology and accurately measure the thrust coefficient of a pintle nozzle under different working conditions, the present invention provides a throat plug nozzle thrust coefficient testing method and testing system.

[0005] A method for calculating a thrust coefficient of a throat-type nozzle includes a throat-type nozzle test model and a thrust coefficient calculation method; the throat-type nozzle test model includes a first throat-type nozzle, a second throat-type nozzle, and a third throat-type nozzle; a thrust line of the first throat-type nozzle and a thrust line of the third throat-type nozzle are collinear; a thrust line of the second throat-type nozzle is perpendicular to the thrust line of the first throat-type nozzle; a plane rectangular coordinate system is established with a horizontal plane where the thrust line of the second throat-type nozzle is located; the thrust line of the second throat-type nozzle is an X-axis; the projections of the thrust lines of the first throat-type nozzle and the third throat-type nozzle on the plane rectangular coordinate system are a Y-axis; the second throat-type nozzle is located in a direction where the X-axis is greater than zero; the first throat-type nozzle and the third throat-type nozzle are arranged on both sides of the origin of the Y-axis;

[0006] The steps of the thrust coefficient calculation method are:

[0007] According to the engine balance pressure formula:

[0008]

[0009] Among them, p c is the combustion chamber pressure, a is the burning rate coefficient, ρ is the propellant density, C* is the characteristic velocity, and n is the pressure exponent; A b A is the burning surface of the grain; t-tot is the total laryngeal area;

[0010] After the propellant is determined, the burning rate coefficient a, propellant density ρ, characteristic velocity C*, and pressure index n are all known constants. b is a known quantity that varies with working time;

[0011] Based on the throat plug nozzle test model, according to the engine balance pressure calculation formula, at the specified combustion chamber pressure p c Next, we first calculate the total throat area A of the three nozzles based on the engine balance pressure calculation formula and known parameters. t-tot After the throat area of ​​the second throat plug nozzle is determined, the throat areas of the first and third throat plug nozzles are adjusted to make the total throat area of ​​the three nozzles reach A t-tot , the combustion chamber pressure p c ;

[0012] According to the specified combustion chamber pressure p c The first throat plug nozzle obtained from the test has a throat area of ​​A t The thrust F at this time, according to the thrust formula F=p c A t C f , the corresponding thrust coefficient C can be calculated f ;

[0013] Changing the combustion chamber pressure p c and the throat area A of the second throat plug nozzle t , we can get the thrust coefficient of the second throat plug nozzle at different pressures and different throat areas.

[0014] Furthermore, a test system for calculating the thrust coefficient of a throat plug nozzle is applied, comprising an engine combustion chamber, an ignition device, a servo control system, a sealing connection structure, a static frame, a dynamic frame, a thrust sensor and a bearing pier;

[0015] The engine combustion chamber includes a barrel section, a bottom cover and a head; the head is provided on the top surface of the barrel section; the bottom cover is provided on the bottom surface of the barrel section; a first through hole, a second through hole and a third through hole are provided on the outer surface of the head; the position of the first through hole is the same as the position of the first throat bolt nozzle of the throat bolt nozzle test model; the position of the second through hole is the same as the position of the second throat bolt nozzle of the throat bolt nozzle test model; the position of the third through hole is the same as the position of the third throat bolt nozzle of the throat bolt nozzle test model; a first flange seat is provided in the first through hole; a second flange seat is provided in the second through hole; a third flange seat is provided in the third through hole; a first throat bolt nozzle is provided in the first flange seat; a second throat bolt nozzle is provided in the second flange seat; a third throat bolt nozzle is provided in the third flange seat; the head and barrel section are fixedly connected by a sealing connection structure;

[0016] The engine combustion chamber is arranged on the moving frame;

[0017] The movable frame includes a base and a roller; the base is a rectangular plate; the base is fixedly connected to the bottom cover; the roller is provided on the bottom surface of the base; the engine combustion chamber is perpendicular to the base;

[0018] A dynamic frame is arranged inside the static frame; the static frame includes a load-bearing pier and a base; the base is parallel to the horizontal plane; the load-bearing pier and the dynamic frame are arranged on the top surface of the base; a thrust sensor is arranged on the load-bearing pier; one end of the thrust sensor is fixedly connected to the load-bearing pier; the other end of the thrust sensor is fixedly connected to the engine combustion chamber; the position where the thrust sensor is fixedly connected to the engine combustion chamber is located on the thrust line of the second throat plug nozzle.

[0019] Furthermore, the sealing connection structure includes a bottom flange of the cover, a top flange of the barrel section, and bolts; the bottom flange of the cover is provided on the outer circumference of the bottom surface of the cover; the bottom flange of the cover is a circular ring; a plurality of screw holes are provided on the end surface of the bottom flange of the cover; the top flange of the barrel section is provided on the outer circumference of the top surface of the barrel section; the top flange of the barrel section is a circular ring; a plurality of screw holes are provided on the top flange of the barrel section; the bottom flange of the cover and the top flange of the barrel section are fixedly connected by bolts;

[0020] Furthermore, the first throat plug nozzle, the second throat plug nozzle and the third throat plug nozzle are respectively provided with actuators;

[0021] Furthermore, a fourth through hole is provided on the outer surface of the head; an ignition device is provided in the fourth through hole; a fifth through hole is provided on the outer surface of the head; the fifth through hole is a pressure measuring hole; a pressure sensor is provided in the fifth through hole; the pressure sensor and the actuator are respectively connected to the servo control system.

[0022] Furthermore, the servo control system includes a controller and control software; the controller is connected to the actuator and the pressure sensor respectively; the controller receives a signal from the pressure sensor, and the control software issues an actuation instruction to the actuator based on the signal from the pressure sensor, driving the throat plug to move axially; after the servo control system collects the combustion chamber pressure, it performs closed-loop control on the throat area of ​​the nozzle, thereby improving the adjustment accuracy of the combustion chamber pressure and obtaining a more accurate thrust coefficient;

[0023] Furthermore, a charge is provided in the combustion chamber; and an insulating structure and a lining are provided in sequence between the charge and the barrel section, the cover and the bottom cover;

[0024] Furthermore, a thrust transfer structure is provided on the cover; the thrust transfer structure is connected to the engine combustion chamber to facilitate the transmission of thrust; the thrust transfer structure is a rectangular plate; a flange is provided on the bottom surface of the thrust transfer structure; the flange is fixedly connected to the cover; a through hole is provided on the side surface of the thrust transfer structure; the through hole is used to set the thrust sensor;

[0025] Furthermore, the thrust transfer structure and the cover are integrally processed.

[0026] The beneficial effects of the present invention are:

[0027] 1. The present invention designs an engine for testing the thrust coefficient of a throat-plug nozzle. A throat-plug nozzle is installed on each of the engine's quadrant lines I, II, and IV. The thrust test of the nozzle on the quadrant line I can be achieved by using a conventional thrust test step structure.

[0028] 2. Continuous adjustment of the throat area is achieved by adjusting the throat plug position of the nozzle on the Quadrant I line. Combustion chamber pressure regulation is achieved by equally adjusting the throat areas of the nozzles on the Quadrant II and IV lines. The thrust generated by the nozzle on the Quadrant I line is obtained from the test. The thrust coefficient corresponding to different pressures and different throat areas of the nozzle on the Quadrant I line can be calculated according to the thrust formula. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the traditional pintle nozzle structure;

[0030] Figure 2 Testing the engine's structure for thrust coefficient;

[0031] Figure 3 This is a cross-sectional view of the engine;

[0032] Figure 4 This is a top view of the engine combustion chamber;

[0033] Figure 5 It is the combustion chamber structure;

[0034] Figure 6It is the top view of the head;

[0035] Figure 7 This is a schematic diagram of the thrust test bench;

[0036] Figure 8 This is a top view of the thrust test bench;

[0037] In the figure, T1 is the gas outlet; T2 is the throat area that changes with the actuation of the throat plug; T3 is the throat plug body; T4 is the gas inlet; T5 is the thrust nozzle; 1 is the combustion chamber; 2 is the throat plug nozzle; 3 is the servo control system; 4 is the ignition device; 5 is the sealing connection structure; 6 is the static frame; 7 is the dynamic frame; 8 is the thrust sensor; 9 is the bearing pier; 1a is the bottom cover; 1b is the barrel section; 1c is the head; 1d is the insulation structure; 1e is the liner; 1f is the charge column; 1c-1 is the thrust transfer structure; 1c-2 is the pressure measuring hole; 1c-3 is the first hanging point; 1c-4 is the third flange; 1c-5 is the second flange; 1c-6 is the first flange; 1c-7 is the second hanging point; 1c-8 is the ignition hole. DETAILED DESCRIPTION

[0038] A method for calculating a thrust coefficient of a throat-type nozzle includes a throat-type nozzle test model and a thrust coefficient calculation method; the throat-type nozzle test model includes a first throat-type nozzle, a second throat-type nozzle, and a third throat-type nozzle; a thrust line of the first throat-type nozzle and a thrust line of the third throat-type nozzle are collinear; a thrust line of the second throat-type nozzle is perpendicular to the thrust line of the first throat-type nozzle; a plane rectangular coordinate system is established with a horizontal plane where the thrust line of the second throat-type nozzle is located; the thrust line of the second throat-type nozzle is an X-axis; the projections of the thrust lines of the first throat-type nozzle and the third throat-type nozzle on the plane rectangular coordinate system are a Y-axis; the second throat-type nozzle is located in a direction where the X-axis is greater than zero; the first throat-type nozzle and the third throat-type nozzle are arranged on both sides of the origin of the Y-axis;

[0039] The steps of the thrust coefficient calculation method are:

[0040] According to the engine balance pressure formula:

[0041]

[0042] Among them, p c is the combustion chamber pressure, a is the burning rate coefficient, ρ is the propellant density, C* is the characteristic velocity, and n is the pressure exponent; A b A is the burning surface of the grain; t-tot is the total laryngeal area;

[0043] After the propellant is determined, the burning rate coefficient a, propellant density ρ, characteristic velocity C*, and pressure index n are all known constants. bis a known quantity that varies with working time;

[0044] Based on the throat plug nozzle test model, according to the engine balance pressure calculation formula, at the specified combustion chamber pressure p c Next, we first calculate the total throat area A of the three nozzles based on the engine balance pressure calculation formula and known parameters. t-tot After the throat area of ​​the second throat plug nozzle is determined, the throat areas of the first and third throat plug nozzles are adjusted to make the total throat area of ​​the three nozzles reach A t-tot , the combustion chamber pressure p c ;

[0045] According to the specified combustion chamber pressure p c The first throat plug nozzle obtained from the test has a throat area of ​​A t The thrust F at this time, according to the thrust formula F=p c A t C f , the corresponding thrust coefficient C can be calculated f ;

[0046] Changing the combustion chamber pressure p c and the throat area A of the second throat plug nozzle t , we can get the thrust coefficient of the second throat plug nozzle at different pressures and different throat areas;

[0047] A test system for calculating the thrust coefficient of a throat-type nozzle is used, including an engine combustion chamber, an ignition device, a servo control system, a sealing connection structure, a static frame, a dynamic frame, a thrust sensor, and a bearing block.

[0048] The engine combustion chamber includes a barrel section, a bottom cover and a head; the head is provided on the top surface of the barrel section; the bottom cover is provided on the bottom surface of the barrel section; a first through hole, a second through hole and a third through hole are provided on the outer surface of the head; the position of the first through hole is the same as the position of the first throat bolt nozzle of the throat bolt nozzle test model; the position of the second through hole is the same as the position of the second throat bolt nozzle of the throat bolt nozzle test model; the position of the third through hole is the same as the position of the third throat bolt nozzle of the throat bolt nozzle test model; a first flange seat is provided in the first through hole; a second flange seat is provided in the second through hole; a third flange seat is provided in the third through hole; a first throat bolt nozzle is provided in the first flange seat; a second throat bolt nozzle is provided in the second flange seat; a third throat bolt nozzle is provided in the third flange seat; the head and barrel section are fixedly connected by a sealing connection structure;

[0049] The sealing connection structure includes a bottom flange of the cover, a top flange of the barrel section, and bolts; the bottom flange of the cover is provided on the outer circumference of the bottom surface of the cover; the bottom flange of the cover is a circular ring; a plurality of screw holes are provided on the end surface of the bottom flange of the cover; the top flange of the barrel section is provided on the outer circumference of the top surface of the barrel section; the top flange of the barrel section is a circular ring; a plurality of screw holes are provided on the top flange of the barrel section; the bottom flange of the cover and the top flange of the barrel section are fixedly connected by bolts;

[0050] The engine combustion chamber is arranged on the moving frame;

[0051] The movable frame includes a base and a roller; the base is a rectangular plate; the base is fixedly connected to the bottom cover; the roller is provided on the bottom surface of the base; the engine combustion chamber is perpendicular to the base;

[0052] The dynamic frame is arranged inside the static frame; the static frame includes a bearing pier and a base; the base is parallel to the horizontal plane; the bearing pier is arranged on the top surface of the base; a thrust sensor is arranged on the bearing pier; one end of the thrust sensor is fixedly connected to the bearing pier; the other end of the thrust sensor is fixedly connected to the engine combustion chamber; the position where the thrust sensor is fixedly connected to the engine combustion chamber is located on the thrust line of the second throat plug nozzle;

[0053] Actuators are respectively provided on the first throat plug nozzle, the second throat plug nozzle and the third throat plug nozzle;

[0054] A fourth through hole is provided on the outer surface of the head; an ignition device is provided in the fourth through hole; a fifth through hole is provided on the outer surface of the head; the fifth through hole is a pressure measuring hole; a pressure sensor is provided in the fifth through hole;

[0055] The pressure sensor and the actuator are respectively connected to the servo control system;

[0056] The servo control system includes a controller and control software; the controller is connected to the actuators respectively; the controller drives the throat plug to move axially according to instructions; the pressure sensor is used to collect the combustion chamber pressure, and the controller receives the combustion chamber pressure signal and issues an actuation instruction to the actuator according to the control software; after the servo control system collects the combustion chamber pressure, it performs closed-loop control on the throat area of ​​the nozzle, thereby improving the adjustment accuracy of the combustion chamber pressure and obtaining a more accurate thrust coefficient;

[0057] A charge is arranged in the combustion chamber; an insulation structure and a lining are arranged in sequence between the charge and the barrel section, the cover and the bottom cover;

[0058] The cover is provided with a thrust transfer structure; the thrust transfer structure is connected to the engine combustion chamber to facilitate thrust transmission; the thrust transfer structure is a rectangular plate; a flange is provided on the bottom surface of the thrust transfer structure; the flange is fixedly connected to the cover; a through hole is provided on the side surface of the thrust transfer structure; the through hole is used to install a thrust sensor;

[0059] The thrust transfer structure and the cover are processed in an integrated manner.

[0060] The present invention will be further described below with reference to the accompanying drawings and examples.

[0061] The structure and appearance of the thrust coefficient test engine are shown in Figure 2 , engine cross-section diagram see Figure 3 , engine top view see Figure 4 ,Depend on Figure 4 The definitions of quadrant lines I, II, III, and IV are shown, and the quadrant line definitions of each component are consistent with the engine. The engine consists of a combustion chamber, three throat-type nozzles, an ignition device, a servo control system, and a sealing connection structure. The engine is placed vertically on the ground, and the thrust lines of the three throat-type nozzles are parallel to the ground. The engine achieves continuous adjustment of the throat area by adjusting the throat position of the nozzle on the quadrant line I, and achieves combustion chamber pressure regulation by equally adjusting the throat area of ​​the nozzle on the quadrant lines II and IV. The thrust generated by the nozzle on the quadrant line I is obtained by testing. According to the thrust formula F=p c A t C f The thrust coefficient of the nozzle on the quadrant I line corresponding to different pressures and different throat areas can be calculated.

[0062] Combustion Chamber:

[0063] Combustion chamber structure Figure 5 The combustion chamber consists of a bottom cover, a barrel section, a head, an insulation structure, a liner, and a charge.

[0064] The bottom cover is a stepped, disc-shaped structure, made of high-strength steel, such as 30CrMnSiA. It features threaded holes and through-holes evenly distributed around the circumference. The threaded holes connect to the barrel, while the through-holes connect to the test fixture, securing the engine.

[0065] The barrel section is cylindrical and can be made of high-strength steel, such as 30CrMnSiA steel. Threaded holes and through-holes are evenly spaced circumferentially at both ends of the barrel section. The threaded holes are used to connect to the head, while the through-holes are used to connect to the bottom cover. Seal grooves are designed on the end faces for installing sealing rings.

[0066] The head is an ellipsoidal structure with three flange seats spaced 90° apart in the circumference. High-strength steel materials such as 30CrMnSiA steel can be used. Figure 6. The outer end of the head is designed with circumferentially evenly distributed through holes for connection with the barrel section. Flange seats are designed on the quadrant lines I, II and IV for installing three throat-type nozzles. Pressure measuring holes and ignition holes are designed on the upper surface of the head for installing pressure sensors and ignition electrical connectors. The positions of the pressure measuring holes and ignition holes are based on the structural layout and there are no special requirements. The outer edges of the quadrant lines II and IV of the head extend out the lifting points for engine lifting. The outer edge of the quadrant line III of the head is designed with a thrust transfer structure, which has sufficient strength for transmitting thrust to the thrust sensor. The thrust transfer point is collinear with the thrust line of the throat-type nozzle installed on the quadrant line I. The thrust transfer structure can be processed as a whole with the head, or it can be processed separately and then welded to the head, or it can be processed separately and connected to the head with a plug-in structure.

[0067] The thermal insulation structure can be made of nitrile or EPDM thermal insulation materials commonly used in solid rocket engines, which are bonded to the inside of the combustion chamber to resist the ablation of high-temperature combustion gas in the combustion chamber.

[0068] The lining layer can be made of a grade that is chemically compatible with the insulation material and propellant, and can be sprayed on the insulation structure of the cast propellant to enhance the adhesion performance of the propellant and relieve stress.

[0069] The grain can use conventional solid propellant, can be cast on the wall or loaded freely, and the grain structure can be designed as needed.

[0070] Laryngeal plug nozzle:

[0071] Three throat-bolt nozzles are mounted on flanges on quadrants I, II, and IV of the head, with the nozzle thrust lines collinear with the quadrant lines and the nozzle outlets facing outward. The thrust transfer point on quadrant III of the head is collinear with the throat-bolt nozzle thrust line on quadrant I.

[0072] Ignition device:

[0073] The ignition device consists of an ignition electrical connector and an ignition charge. The ignition charge is bonded to the surface of the charge. The ignition electrical connector is mounted on the head. The cable inside the connector is connected to the ignition charge. The cable outside receives the ignition current, igniting the ignition charge, which in turn ignites the charge.

[0074] Servo control system:

[0075] The servo control system consists of three actuators, a pressure sensor, a controller, cables, and control software. The three actuators are mounted on three throat-plug nozzles, driving the throat plugs for axial movement according to commands. The pressure sensor, mounted on the head, collects combustion chamber pressure and provides it to the controller. The controller receives the combustion chamber pressure signal and issues actuation commands to the actuators based on the control software's algorithm. Cables connect the controller to the actuators, pressure sensor, and power supply for power supply and communication. The control software, installed in the controller, drives the hardware, processes signals, and issues actuation commands based on the control algorithm.

[0076] Sealed connection structure:

[0077] The sealing connection structure is used for connection and sealing between various components of the engine, including bolts, spring washers and sealing rings.

[0078] Thrust test bench:

[0079] Thrust test bench Figure 7 , top view Figure 8 , including a static frame, a dynamic frame, a thrust sensor, and a bearing pier. The dynamic frame has a bearing roller, which is installed on the track of the static frame and can roll along the track. The thrust sensor is installed on the bearing pier. The engine is installed on the dynamic frame through the bottom cover. The thrust line of the throat plug nozzle of the quadrant line I is parallel to the dynamic frame track, and the thrust transfer point of the quadrant line III is in contact with the thrust sensor. The thrust of the throat plug nozzle of the quadrant line I can be tested through the thrust test bench. By adjusting the throat plug stroke of the quadrant line nozzle, the throat area of ​​the quadrant line nozzle can be changed to achieve thrust testing of different throat areas.

[0080] Combustion chamber pressure realization method:

[0081] The formula for engine equilibrium pressure is: After the propellant is selected, the burning rate coefficient a, propellant density ρ, characteristic velocity C * , pressure index n are known constants, the burning surface A b is a known quantity that changes with working time. In order to achieve the specified combustion chamber pressure p c First, the total throat area A of the three nozzles is calculated based on the engine balance pressure formula and known parameters. t-tot After the nozzle throat area of ​​quadrant I is determined, the nozzle throat areas of quadrant II and IV are adjusted to make the total throat area of ​​the three nozzles reach A. t-tot , so that the combustion chamber pressure p c .

[0082] After the servo control system collects the combustion chamber pressure, it can perform closed-loop control on the throat area of ​​the II and IV quadrant line nozzles, thereby improving the adjustment accuracy of the combustion chamber pressure.

[0083] In this way, the specified combustion chamber pressure p is achieved. c The throat area of ​​the nozzle on the quadrant I line obtained from the test is A t The thrust F at this time, according to the thrust formula F=p c A t C f The corresponding thrust coefficient can be calculated. c and the nozzle throat area A on the quadrant I line t , we can get the thrust coefficient of the nozzle on the quadrant I line at different pressures and different throat areas.

[0084] Beneficial effects:

[0085] 1. The present invention designs an engine for testing the thrust coefficient of a throat-plug nozzle. A throat-plug nozzle is installed on each of the engine's quadrant lines I, II, and IV. The thrust test of the nozzle on the quadrant line I can be achieved by using a conventional thrust test step structure.

[0086] 2. The throat area is continuously adjusted by adjusting the position of the nozzle throat plug on the quadrant I line. The combustion chamber pressure is regulated by adjusting the throat area of ​​the nozzles on the quadrant II and IV lines. The thrust generated by the nozzle on the quadrant I line is obtained by testing. According to the thrust formula F = p c A t C f The thrust coefficient of the nozzle on the quadrant I line corresponding to different pressures and different throat areas can be calculated.

Claims

1. A method for calculating the thrust coefficient of a throat plug nozzle, characterized by: Including the test model of the plug-type nozzle and the thrust coefficient calculation method; The throat-bolt nozzle test model includes a first throat-bolt nozzle, a second throat-bolt nozzle, and a third throat-bolt nozzle; the thrust line of the first throat-bolt nozzle and the thrust line of the third throat-bolt nozzle are collinear; the thrust line of the second throat-bolt nozzle is perpendicular to the thrust line of the first throat-bolt nozzle; a plane rectangular coordinate system is established with the horizontal plane where the thrust line of the second throat-bolt nozzle is located; the thrust line of the second throat-bolt nozzle is the X-axis; the projections of the thrust lines of the first throat-bolt nozzle and the third throat-bolt nozzle on the plane rectangular coordinate system are the Y-axis; the second throat-bolt nozzle is located in a direction where the X-axis is greater than zero; the first throat-bolt nozzle and the third throat-bolt nozzle are arranged on both sides of the origin of the Y-axis; The steps of the thrust coefficient calculation method are: According to the engine balance pressure formula: ； in, is the combustion chamber pressure, Burning rate coefficient, is the propellant density, is the characteristic velocity, is the pressure index; It is the burning surface of the charge; is the total laryngeal area; After the propellant is determined, the burning rate coefficient , propellant density , characteristic velocity , pressure index All are known constants, the burning surface of the grain is a known quantity that varies with working time; Based on the throat plug nozzle test model, according to the engine balance pressure calculation formula, at the specified combustion chamber pressure First, according to the engine balance pressure calculation formula and known parameters, the total throat area of ​​the three nozzles is calculated. After the throat area of ​​the second throat plug nozzle is determined, the throat areas of the first and third throat plug nozzles are adjusted to make the total throat area of ​​the three nozzles reach , that is, to achieve the combustion chamber pressure ; According to the specified combustion chamber pressure The first throat plug nozzle obtained from the test has a throat area of Thrust , according to the thrust formula , that is, solve the corresponding thrust coefficient ; Changing the combustion chamber pressure and the throat area of ​​the second throat plug nozzle , that is, the thrust coefficient of the second throat plug nozzle corresponding to different pressures and different throat areas is obtained.

2. A test system using the method for calculating the thrust coefficient of a throat plug nozzle according to claim 1, characterized in that: It includes an engine combustion chamber, a static frame, a dynamic frame, a thrust sensor and a bearing pier; the static frame includes a base; the base is parallel to the horizontal plane; the dynamic frame and the bearing pier are arranged on the base; the engine combustion chamber is arranged on the dynamic frame; the engine combustion chamber and the bearing pier are connected via a thrust sensor; The engine combustion chamber includes a barrel section, a bottom cover and a sealing cover; a sealing cover is provided on the top surface of the barrel section; a bottom cover is provided on the bottom surface of the barrel section; the sealing cover and the barrel section are fixedly connected by a sealing connection structure; a first through hole, a second through hole and a third through hole are provided on the outer surface of the sealing cover; the position of the first through hole is the same as the position of the first throat bolt nozzle of the throat bolt nozzle test model; the position of the second through hole is the same as the position of the second throat bolt nozzle of the throat bolt nozzle test model; the position of the third through hole is the same as the position of the third throat bolt nozzle of the throat bolt nozzle test model; a first flange seat is provided in the first through hole; a second flange seat is provided in the second through hole; a third flange seat is provided in the third through hole; a first throat bolt nozzle is provided on the first flange seat; a second throat bolt nozzle is provided on the second flange seat; and a third throat bolt nozzle is provided on the third flange seat; The dynamic frame includes a base and a roller; the base is a rectangular plate; the base is fixedly connected to the bottom cover; a roller is provided on the bottom surface of the base; the engine combustion chamber is perpendicular to the base; a thrust sensor is provided on the load-bearing pier; one end of the thrust sensor is fixedly connected to the load-bearing pier; the other end of the thrust sensor is fixedly connected to the engine combustion chamber; the position where the thrust sensor is fixedly connected to the engine combustion chamber is located on the thrust line of the second throat plug nozzle.

3. The test system for calculating the thrust coefficient of a throat plug nozzle according to claim 2, characterized in that: The sealing connection structure includes a bottom flange of the cover, a top flange of the barrel section and bolts; the bottom flange of the cover is provided on the outer circumference of the bottom surface of the cover; the bottom flange of the cover is a circular ring; a plurality of screw holes are provided on the end face of the bottom flange of the cover; the top flange of the barrel section is provided on the outer circumference of the top surface of the barrel section; the top flange of the barrel section is a circular ring; a plurality of screw holes are provided on the top flange of the barrel section; the bottom flange of the cover and the top flange of the barrel section are fixedly connected by bolts.

4. The test system for calculating the thrust coefficient of a throat plug nozzle according to claim 2, characterized in that: Actuators are respectively provided on the first throat plug type nozzle, the second throat plug type nozzle and the third throat plug type nozzle.

5. The test system for calculating the thrust coefficient of a throat plug nozzle according to claim 4, characterized in that: A fourth through hole is provided on the outer surface of the cover; an ignition device is provided in the fourth through hole; a fifth through hole is provided on the outer surface of the cover; the fifth through hole is a pressure measuring hole; a pressure sensor is provided in the fifth through hole; the pressure sensor and the actuator are respectively connected to the servo control system.

6. The test system for calculating the thrust coefficient of a throat plug nozzle according to claim 5, characterized in that: The servo control system includes a controller and control software; the controller is connected to the actuator and the pressure sensor respectively; the controller receives the signal from the pressure sensor, and the control software sends an actuation instruction to the actuator based on the signal from the pressure sensor to drive the laryngeal plug to move axially.

7. The test system for calculating the thrust coefficient of a throat plug nozzle according to claim 2, characterized in that: A charge is arranged in the combustion chamber; and a heat-insulating structure and a lining are sequentially arranged between the charge and the barrel section, the sealing cover and the bottom cover.

8. The test system for calculating the thrust coefficient of a throat plug nozzle according to claim 2, characterized in that: A thrust transfer structure is provided on the cover; the thrust transfer structure is connected to the engine combustion chamber to facilitate the transmission of thrust; the thrust transfer structure is a rectangular plate; a flange is provided on the bottom surface of the thrust transfer structure; the flange is fixedly connected to the cover; a through hole is provided on the side surface of the thrust transfer structure; the through hole is used to set a thrust sensor.

9. The test system for calculating the thrust coefficient of a throat plug nozzle according to claim 8, characterized in that: The thrust transfer structure and the cover are processed in an integrated manner.

Images