A method for thrust control of an extruded primary rocket

Abstract

The application discloses a thrust control method of an extrusion type first-stage rocket, which is executed by a flight control computer, and the extrusion type first-stage rocket is provided with a liquid nitrogen turbine pump for pressurized liquid nitrogen, and liquid nitrogen is used to extrude propellant in a propellant storage tank after being gasified by a vaporizer. The application establishes a complete closed-loop thrust control logic based on a large-thrust power system with liquid nitrogen turbine pump pressurization and liquid nitrogen gasification extrusion of propellant as a power transmission basis, provides a reliable benchmark for precise regulation and control of thrust, and realizes precise large-thrust output of the extrusion type first-stage rocket. The application realizes precise isolation of a fault system by reducing the liquid outlet valve of the failed system to the minimum safety opening degree, avoids the risk of leakage caused by abnormal excessive extrusion of a single propellant to a thrust chamber due to pressurization, and maximizes the remaining system's load distribution to retain the whole rocket's thrust output capacity, and takes into account fault tolerance and task continuity.

Description

Technical Field

[0001] This invention relates to the field of launch vehicle propulsion control technology, and in particular to a thrust control method for a multi-engine parallel compression-type first-stage rocket. Background Technology

[0002] Existing thrust control systems for squeeze rockets mostly employ single-loop regulation schemes, which suffer from technical defects such as weak disturbance resistance, low thrust tracking accuracy, and poor fault tolerance. In particular, for high-thrust propulsion systems equipped with liquid nitrogen turbopumps and liquid nitrogen vaporized squeeze propellants, existing technologies have not developed targeted control strategies and cannot be adapted to the high thrust output of squeeze rockets as first-stage rockets.

[0003] This defect will result in: the lack of effective cascade coordinated control of the liquid nitrogen turbopump speed, which will directly affect the liquid nitrogen vaporization efficiency and the compression pressure of all tanks; if the distribution accuracy of the three booster pressures, the anti-disturbance capability of the propellant mixture ratio, and the degradation logic under fault conditions are not adapted to the working characteristics of the power system, it will lead to insufficient thrust control accuracy, poor system stability, and inability to meet the requirements of high-precision flight. To address this, the present invention proposes a thrust control method based on cascade PID control, weighted pressure distribution, adaptive cooling, and fault degradation, which precisely matches the high-thrust power system of liquid nitrogen turbopump and liquid nitrogen vaporization extrusion, thereby improving thrust control accuracy and power system reliability. Summary of the Invention

[0004] To overcome the shortcomings mentioned above, the present invention aims to provide a technical solution that can solve the above problems.

[0005] A thrust control method for a squeeze-type first-stage rocket, wherein the thrust control method is executed by a flight control computer, the squeeze-type first-stage rocket is equipped with a liquid nitrogen turbopump for pressurizing liquid nitrogen, the liquid nitrogen being vaporized by a vaporizer and then squeezing the propellant in the propellant tank, the thrust control method comprising: S1. Real-time acquisition of target thrust command, thrust chamber pressure, three-way booster pressure, and liquid nitrogen turbine pump speed, wherein the three-way booster pressure includes oxygen tank pressure, fuel tank pressure, and nitrogen tank pressure; S2. Based on the mapping model of preset thrust, preset pressure, and preset flow rate, calculate the target thrust chamber pressure, target oxygen flow rate, target fuel flow rate, and target liquid nitrogen turbopump speed. S3. A cascaded PID control algorithm is adopted, with the outer loop using the thrust chamber pressure as feedback and the inner loop using the liquid nitrogen turbine pump speed as feedback. The opening of the gas extraction control valve is adjusted to control the flow rate of the ejected gas in the thrust chamber, thereby stabilizing the boost pressure of the liquid nitrogen turbine pump and the intake volume of the vaporizer. S4. Based on the weighted distribution algorithm of the three boosting pressures, adjust the opening of the oxygen tank boosting valve, fuel tank boosting valve, and nitrogen tank boosting valve in real time to maintain the three boosting pressures within the set range and achieve balanced distribution of extrusion pressure. S5. Based on the target oxygen flow rate and target fuel flow rate, adjust the opening of the oxygen tank outlet valve and the fuel tank outlet valve, using the thrust chamber pressure and mixing ratio as feedback, to keep the propellant mixing ratio stable within the design range. S6. Using the measured thrust chamber pressure as the controlled variable, the liquid nitrogen turbopump speed, the three-way booster pressure, the opening of the oxygen tank outlet valve, and the opening of the fuel tank outlet valve are corrected step by step to achieve thrust tracking and to implement safety interlocks for overpressure, liquid nitrogen turbopump overspeed, and mixture ratio over-limit. Preferably, the cascaded PID control includes: The outer loop outputs the target speed and the target total boost pressure; The inner ring adjusts the opening of the gas extraction control valve based on the difference between the target speed and the measured speed. Feedforward compensation for liquid nitrogen temperature, liquid level, and tank pressure is introduced to suppress disturbances; Preferably, the weighted allocation algorithm for the three-way boosting pressure satisfies: P_ox=α・P_total P_fuel=β・P_total P_n2=γ・P_totalα+β+γ=1 Where P_total is the total boost pressure, and α, β, and γ are the allocation coefficients optimized by the software in real time; Preferably, an offline mapping table of wall temperature and liquid nitrogen flow rate is established in S6, with a control cycle of 1–10 ms, and adaptive thin film cooling is achieved through table lookup and fine-tuning; Preferably, the thrust control method for the squeeze-type first-stage rocket further includes fault degradation control: When oxidizer boost failure is detected, the corresponding fuel flow rate is immediately reduced and the system enters a low thrust holding mode. When a fuel boost failure is detected, the corresponding oxygen flow is immediately reduced and the system enters a low thrust holding mode. When liquid nitrogen pressurization failure is detected, the turbine speed is reduced and the total thrust is decreased to maintain closed-loop stability.

[0006] Compared with the prior art, the advantages of the present invention are: This invention relies on a high-thrust propulsion system based on liquid nitrogen turbopump pressurization and liquid nitrogen vaporization extrusion propellant as the power transmission basis. It establishes a complete closed-loop thrust control logic, collects key state parameters at millisecond intervals through the flight control computer, and accurately calculates the parameters of each control target by combining the mapping model, providing a reliable benchmark for precise thrust control and realizing the precise high-thrust output of the extrusion-type first-stage rocket.

[0007] This invention employs a cascaded PID dual closed-loop control system consisting of an outer loop for thrust chamber pressure and an inner loop for liquid nitrogen turbine pump speed. Combined with the adjustment of the ejector gas control valve opening, it can quickly stabilize the working state of the liquid nitrogen turbine pump, the liquid nitrogen boosting pressure, and the vaporizer intake volume, suppressing the tank extrusion pressure disturbance caused by fluctuations in liquid nitrogen vaporization efficiency, and improving the stability of propellant supply and the accuracy of thrust steady-state control.

[0008] This invention establishes an offline mapping table between thrust chamber wall temperature and liquid nitrogen flow rate, and combines this with adaptive fine-tuning of liquid nitrogen supply based on vaporizer outlet temperature to form a stable thin-film cooling layer on the thrust chamber wall, thereby stabilizing and controlling the wall temperature within a reasonable range. This effectively prevents high-temperature ablation of the thrust chamber, extending the structural service life and operational reliability.

[0009] This invention achieves precise isolation of the faulty system by reducing the outlet valve of the failed system to the minimum safe opening, avoiding the risk of leakage caused by excessive compression of a single propellant into the thrust chamber due to abnormal pressurization. Furthermore, it maximizes the retention of the entire rocket's thrust output capacity through dynamic load distribution of the remaining system, balancing fault tolerance and mission continuity.

[0010] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the thrust control method of the present invention.

[0013] Figure 2 This is a schematic diagram of the fault degradation control of the present invention.

[0014] Figure 3 This is a structural diagram of the propulsion system of the compression-type first-stage rocket controlled by the present invention. Detailed Implementation

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0017] Furthermore, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0018] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] Please see Figures 1-2 In this embodiment of the invention, a thrust control method for a squeeze-type first-stage rocket is provided. The thrust control method is executed by a flight control computer. The power transmission basis of the squeeze-type first-stage rocket is as follows: the rocket is equipped with a liquid nitrogen turbopump 400. The liquid nitrogen turbopump 400 pressurizes the liquid nitrogen and delivers it to the vaporizer 600. The liquid nitrogen absorbs heat and vaporizes in the vaporizer to form high-pressure nitrogen gas. The high-pressure nitrogen gas is introduced into the oxygen tank 100, the fuel tank 200, and the nitrogen tank 300 respectively. The gas pressure squeezes the propellant (liquid oxygen / fuel) in the tank, so that the propellant is delivered to the thrust chamber for combustion at a set flow rate to generate thrust.

[0020] In this embodiment, the thrust control method includes: S1. The flight control computer collects core parameters in real time at a 1ms cycle, including target thrust command, thrust chamber pressure (reflecting actual thrust), three-way pressurization pressure (pressure of oxygen tank 100 / fuel tank 200 / nitrogen tank 300, reflecting the extrusion pressure state), and liquid nitrogen turbopump speed of 400 (affecting liquid nitrogen vaporization efficiency). S2. Based on the mapping model of preset thrust, preset pressure, and preset flow rate, calculate the target thrust chamber pressure, target oxygen flow rate, target fuel flow rate, and target liquid nitrogen turbine pump speed of 400 rpm, providing a benchmark for subsequent control. S3. A cascaded PID control algorithm is used to achieve dual closed-loop coordination: the outer loop uses the thrust chamber pressure as feedback to output the target liquid nitrogen turbopump speed of 400 and the target total boost pressure, ensuring that the actual thrust approaches the target value; the inner loop uses the liquid nitrogen turbopump speed of 400 as feedback to control the injection gas flow rate by adjusting the opening of the gas extraction control valve 500, accurately stabilizing the liquid nitrogen turbopump speed of 400, thereby stabilizing the liquid nitrogen boost pressure and the vaporizer intake volume, avoiding the instability of extrusion pressure caused by fluctuations in liquid nitrogen vaporization efficiency; S4. A weighted allocation algorithm based on three boosting pressures (satisfying P_ox=α・P_total, P_fuel=β・P_total, P_n2=γ・P_total, and α+β+γ=1, where P_total is the total boosting pressure, and α, β, and γ are allocation coefficients optimized by the software in real time) is used to adjust the opening of the boosting valves of oxygen tank 100, fuel tank 200, and nitrogen tank 300 in real time, maintain the three boosting pressures within the set range, achieve balanced distribution of extrusion pressure, and avoid unstable propellant delivery caused by excessively high or low pressure in a single tank. S5. Based on the target oxygen flow rate and target fuel flow rate, adjust the opening of the liquid outlet valve of oxygen tank 100 and the liquid outlet valve of fuel tank 200. With the thrust chamber pressure and mixing ratio as feedback, when the mixing ratio deviation is the main factor, prioritize adjusting the opening of the liquid outlet valve of oxygen tank 100. When the thrust chamber pressure deviation is the main factor, simultaneously adjust the opening of the two liquid outlet valves to ensure that the mixing ratio is stable within the design range and to ensure the combustion efficiency of the thrust chamber. S6. Using the measured thrust chamber pressure as the core controlled variable (thrust and pressure have a linear relationship F=k・P_c), the control parameters are corrected step by step to achieve precise thrust tracking. At the same time, safety interlocks are executed. When the thrust chamber pressure exceeds the limit (≥22MPa), the liquid nitrogen turbopump exceeds the limit by 400 rpm (≥33000 rpm), or the mixing ratio exceeds the limit (≤1.6 or ≥2.4), emergency valve shut-off, speed reduction, or staged shutdown actions are immediately triggered to prevent the system failure from escalating. During the thrust control process, the liquid nitrogen supply is finely adjusted by looking up the table and combining it with the vaporizer outlet temperature based on the offline mapping table of thrust chamber wall temperature and liquid nitrogen flow rate. This allows liquid nitrogen to form a stable thin film cooling layer on the sweat pores of the thrust chamber wall, maintaining the wall temperature at 300-500℃ and preventing the thrust chamber from overheating and burning.

[0021] In another embodiment, the squeeze-type first-stage rocket is a parallel structure of multiple high-thrust propulsion systems, and its thrust control method also includes fault degradation control: When an oxidizer pressurization failure or fuel pressurization failure is detected in a certain propulsion system, the opening of the liquid outlet valve of the corresponding fuel tank 200 and oxygen tank 100 is immediately reduced to prevent secondary risks such as leakage and unstable combustion caused by excessive pressure of a single propellant being squeezed into the thrust chamber. This achieves physical isolation between the faulty system and the normal system. The flight control computer recalculates the target thrust distribution of the remaining normal propulsion systems and maintains stable total thrust by correcting the speed of the liquid nitrogen turbopump 400, the three-way pressurization pressure, and the opening of its own liquid outlet valve according to the new target thrust. If a single propulsion system experiences a continuous pressurization failure, after isolating the faulty system, if the flight control computer determines that the thrust of the remaining propulsion systems meets the minimum climb requirements, it enters a low-thrust steady-state flight mode to maintain attitude stability and continue flying according to the predetermined trajectory. If the flight control computer determines that the thrust of the remaining propulsion systems is insufficient and cannot maintain a stable climb, it immediately executes the entire rocket shutdown procedure and controlled self-destruct process to avoid the risk of trajectory descent and accidental crash.

[0022] When a failure of the shared liquid nitrogen pressurization is detected, the speed of the liquid nitrogen turbopump 400 is immediately reduced to 60% of its rated value, and the total pressurization pressure is simultaneously reduced to 50% of the target value. The flight control computer simultaneously reduces the target thrust of all power systems, and the total thrust is reduced to 50% of the rated total thrust. The basic compression pressure of each system is maintained by the remaining liquid nitrogen vaporization. The pressure of the nitrogen tank 300 is continuously monitored. If the pressure recovers to more than 80% of the target value, the speed of the liquid nitrogen turbopump 400 and the thrust of each system are gradually increased until the target total thrust is restored. If the liquid nitrogen pressurization continues to fail, and the flight control computer determines that the reduced total thrust can still meet the rocket's minimum climb overload, then low-thrust closed-loop control is maintained to keep the attitude stable and fly along the predetermined trajectory. If the flight control computer determines that the reduced thrust is insufficient to maintain the climb, then the entire rocket's shutdown procedure and controlled self-destruct process are immediately triggered.

[0023] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A thrust control method for a squeeze-type first-stage rocket, characterized in that, The thrust control method is executed by a flight control computer. The squeeze-type first-stage rocket is equipped with a liquid nitrogen turbopump for pressurizing liquid nitrogen. The liquid nitrogen is vaporized by a vaporizer and then used to compress the propellant in the propellant tank. The thrust control method includes: S1. Real-time acquisition of target thrust command, thrust chamber pressure, three-way booster pressure, and liquid nitrogen turbine pump speed, wherein the three-way booster pressure includes oxygen tank pressure, fuel tank pressure, and nitrogen tank pressure; S2. Based on the mapping model of preset thrust, preset pressure, and preset flow rate, calculate the target thrust chamber pressure, target oxygen flow rate, target fuel flow rate, and target liquid nitrogen turbopump speed. S3. A cascaded PID control algorithm is adopted, with the outer loop using the thrust chamber pressure as feedback and the inner loop using the liquid nitrogen turbine pump speed as feedback. The opening of the gas extraction control valve is adjusted to control the flow rate of the ejected gas in the thrust chamber, thereby stabilizing the boost pressure of the liquid nitrogen turbine pump and the intake volume of the vaporizer. S4. Based on the weighted distribution algorithm of the three boosting pressures, adjust the opening of the oxygen tank boosting valve, fuel tank boosting valve, and nitrogen tank boosting valve in real time to maintain the three boosting pressures within the set range and achieve balanced distribution of extrusion pressure. S5. Based on the target oxygen flow rate and target fuel flow rate, adjust the opening of the oxygen tank outlet valve and the fuel tank outlet valve, using the thrust chamber pressure and mixing ratio as feedback, to keep the propellant mixing ratio stable within the design range. S6. Using the measured thrust chamber pressure as the controlled variable, the liquid nitrogen turbopump speed, the three-way booster pressure, the opening of the oxygen tank outlet valve, and the opening of the fuel tank outlet valve are corrected step by step to achieve thrust tracking and to implement safety interlocks for overpressure, liquid nitrogen turbopump overspeed, and mixture ratio exceeding limits.

2. The thrust control method for a squeeze-type first-stage rocket according to claim 1, characterized in that, The cascaded PID control described in S3 includes: The outer loop outputs the target speed and the target total boost pressure; The inner ring adjusts the opening of the gas extraction control valve based on the difference between the target speed and the measured speed. Feedforward compensation is introduced for liquid nitrogen temperature, liquid level, and tank pressure to suppress disturbances.

3. The thrust control method for a squeeze-type first-stage rocket according to claim 1, characterized in that, The weighted allocation algorithm for the three-way boost pressure satisfies: P_ox=α・P_total P_fuel=β・P_total P_n2=γ・P_totalα+β+γ=1 Where P_total is the total boost pressure, and α, β, and γ are the allocation coefficients optimized by the software in real time.

4. The thrust control method for a squeeze-type first-stage rocket according to claim 1, characterized in that, An offline mapping table for wall temperature and liquid nitrogen flow rate is established in S6, with a control cycle of 1–10 ms. Adaptive thin-film cooling is achieved through table lookup and fine-tuning.

5. The thrust control method for a squeeze-type first-stage rocket according to claim 1 further includes fault degradation control, characterized in that: When oxidizer boost failure is detected, the corresponding fuel flow rate is immediately reduced and the system enters a low thrust holding mode. When a fuel boost failure is detected, the corresponding oxygen flow is immediately reduced and the system enters a low thrust holding mode. When liquid nitrogen pressurization failure is detected, the turbine speed is reduced and the total thrust is decreased to maintain closed-loop stability.

Images