An evaluation method for integrated energy system based on fly / launch cooperative control strategy

Abstract

The application discloses a kind of based on the evaluation method of comprehensive energy system of fly / launch collaborative control strategy, it is related to advanced aeronautical power comprehensive energy system. With the comprehensive energy system with multi-source energy extraction mode as the research object, the performance evaluation of comprehensive energy system is realized through the comprehensive evaluation of fly / launch level of typical TBCC engine. Including steps: 1) parameter initialization: 2) establish aircraft dynamics model;3) establish combination engine model;4) establish comprehensive energy system model;5) solve optimal trajectory. The performance influence of different energy extraction modes on combination power is quantitatively analyzed, and the comprehensive evaluation of comprehensive energy system with multi-source energy extraction mode is realized. Under certain energy demand, the fly / launch coordination control for realizing optimal trajectory and lowest fuel consumption is combined, and the evaluation method taking the performance influence of comprehensive energy system on combination power device as evaluation index provides reference value for future comprehensive energy management system design method.

Description

Technical Field

[0001] The present invention relates to an advanced aviation power integrated energy system, and in particular to an integrated energy system evaluation method based on a flight / engine collaborative control strategy. Background Art

[0002] The development of aerospace hypersonic vehicles and combined propulsion technologies has enabled flight over a wide speed range and for extended flight durations. Consequently, the extraction, utilization, and management of onboard energy during these extended flights has become crucial. Due to the unique nature of their operating environments and factors such as mass penalties, hypersonic vehicles struggle to carry sufficient power supply equipment to meet the power needs of all onboard equipment. Therefore, achieving electrical self-sufficiency within these constraints is a major challenge facing energy management for air-breathing hypersonic vehicles.

[0003] Given that energy extraction is of great significance to aircraft carrying out long-duration, wide-range flight missions, we attach great importance to the technical research related to airborne energy systems and have achieved certain results. Currently, the common and relatively mature energy extraction schemes are mainly the following: one is to extract through the engine turbine shaft power; the second is to use the turbine to extract the total enthalpy of the engine intake air / oil and gas; the third is to recover and utilize the aerodynamic heat of the engine wall based on the thermoelectric conversion device; the fourth is the fuel cooling Utilize, turbine power generation based on fuel cracking gas (Li Haowei, Qin Jiang, Gan Jianzhou, et al. Review of the current status of energy management and utilization technology of air-breathing hypersonic aircraft [J]. Cruise Missile, 2021(7):12-17).

[0004] Different energy extraction schemes have varying conversion efficiencies and applicable speed ranges. Therefore, for combined propulsion systems designed for flight over a wide speed range, an integrated energy system is needed to extract energy from multiple sources to meet the aircraft's energy needs across different speed ranges. However, all of these energy extraction methods affect the combined propulsion system's fuel consumption, turbine compressor stability margin, ramjet inlet stability margin, combustion stability, and other performance characteristics, with varying degrees of impact and mechanisms. Therefore, to help combined propulsion systems achieve lower fuel consumption rates under certain energy requirements, it is essential to develop a suitable evaluation method that quantifies the impact of the integrated energy system on their performance. Summary of the Invention

[0005] This paper aims to provide an integrated energy system evaluation method based on a flight / engine coordinated control strategy for advanced aviation propulsion integrated energy systems. This method, focusing on integrated energy systems with multi-source energy extraction, evaluates the performance of these systems through a comprehensive evaluation of the flight / engine level of a typical TBCC engine.

[0006] The present invention comprises the following steps:

[0007] 1) Parameter initialization: Set the target power requirement and initial conditions (flight altitude, Mach, etc.), divide the flight phase into segment points (Ma2, Ma5) based on the characteristics of the combined engine, set constraints and control quantities, and provide a reasonable initial parameter range.

[0008] 2) Establish an aircraft dynamics model: Considering the impact of the trajectory characteristics of the vertical plane climb phase, the aircraft is regarded as a point mass model moving on the vertical plane. The six-degree-of-freedom model of the aircraft is simplified as required, and the state differential equations of various state parameters are established;

[0009] 3) Establish a combined engine model: Under certain flight conditions (Mach number Ma / altitude H), a dynamic model of a typical TBCC engine is established. Ultimately, the angle of attack rate and TBCC throttle lever are used as control variables in combination with the aircraft dynamic model.

[0010] 4) Establishing a comprehensive energy system model: Three energy extraction modes are established for the flight speed range of Ma0-7 to adapt to different operating speed ranges; the power generation mode of the turbine engine high-pressure shaft extracting shaft power is adopted in the Ma0-2 stage (including Ma=2); the power generation mode of the turbine engine high-pressure shaft extracting shaft power is adopted in the Ma2-5 stage (including Ma=5) by drawing air from the inlet duct outlet section to drive the air turbine to generate electricity; the power generation mode of the turbine engine high-pressure shaft extracting shaft power is adopted in the Ma5-7 stage; the power generation mode of the turbine engine high-pressure shaft extracting shaft power is adopted by the Ma0-2 stage (including Ma=2); the power generation mode of the turbine engine high-pressure shaft extracting shaft power is adopted by the Ma2-5 stage (including Ma=5) by drawing air from the inlet duct outlet section to drive the air turbine to generate electricity; the power generation mode of the turbine engine high-pressure shaft extracting shaft power is adopted by the Ma5-7 stage ...

[0011] 5) Solve the optimal trajectory: The optimal trajectory of the aircraft is solved based on the Gaussian pseudospectral method. In combination with the above model, the flight altitude, speed, climb angle, aircraft mass, and angle of attack are set as state parameters, and the rate of change of angle of attack and TBCC throttle lever are set as control variables. The optimization problem of the climb trajectory is expressed as a corresponding cost function and parameter constraints, with minimum fuel consumption as the performance indicator. Based on the optimal result, the impact of the call of the integrated energy system under the optimal trajectory on the overall performance of the combined power is output, and the evaluation of the integrated energy system based on the flight / engine coordinated control strategy is completed.

[0012] In step 3), the specific steps of establishing the combined engine model may be:

[0013] (1) Establishing the combined engine intake model:

[0014] An axisymmetric inlet is selected. Based on the given inlet conditions and inlet design parameters, the model's performance parameters, such as the total pressure recovery coefficient, flow capture coefficient, and drag coefficient, are calculated to obtain the inlet outlet parameters.

[0015] (2) Establishing a turbine engine working model:

[0016] The airflow parameters of each section of the engine and the engine's performance parameters such as unit thrust, fuel consumption rate, and specific impulse are calculated through the working process parameters, and the turbine engine thrust is calculated in combination with the captured air flow.

[0017] (3) Establishing a ramjet engine working model:

[0018] The engine thrust and specific impulse are calculated through the unit flow thrust and specific impulse characteristics, considering only the influence of Mach number and not considering the altitude and throttling characteristics. The unit flow thrust and specific impulse can be obtained by modeling based on the known change law.

[0019] In step 4), the integrated energy system model is established as follows:

[0020] (1) Turbine shaft power extraction model: A certain required power is extracted from the high-pressure shaft of the turbine engine and driven by the transmission device to generate electricity.

[0021] (2) Air turbine power generation model: Based on the total temperature, total pressure and flow rate of the incoming flow at the inlet outlet, the turbine working model is introduced to inversely solve the required target power to obtain the flow rate of the required induced air, and the impact of the induced air on the overall performance of the current combined ramjet engine is iteratively calculated.

[0022] (3) Gas turbine power generation model: After the gas is drawn out at the inlet outlet, it is burned in the combustion chamber. Based on the total temperature, total pressure and flow rate of the gas, the turbine working model is introduced to inversely solve the required target power to obtain the flow rate of the required bleed gas. The total outlet temperature is limited to 2200K, and then the impact of the bleed gas on the overall performance of the current ramjet engine is iteratively calculated.

[0023] The present invention has the following outstanding technical effects:

[0024] Compared to existing evaluation methods, this method, applied to TBCC engines, quantifies the impact of different energy extraction methods on the combined power unit's performance, thereby enabling comprehensive evaluation of integrated energy systems with multiple energy extraction methods. This method, combined with coordinated flight / engine control to achieve optimal flight trajectory and minimize fuel consumption under certain energy requirements, uses the impact of the integrated energy system on the combined power unit's performance as an evaluation metric. This method provides valuable insights into the design of future integrated energy management systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the integrated energy system architecture based on the parallel TBCC engine. DETAILED DESCRIPTION

[0026] The following embodiments will further illustrate the present invention with reference to the accompanying drawings.

[0027] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that technicians may use different terms to refer to the same component.

[0028] The embodiment of the present invention proposes a comprehensive energy system architecture with multi-source energy extraction based on the parallel TBCC engine (such as Figure 1 Specifically, this integrated energy system combines the power characteristics of the parallel TBCC engine and matches the corresponding energy systems to different subcomponents: extracting the high-pressure shaft power of the turbine engine for power generation, bleed air from the ramjet isolation section to generate air turbine power, and bleed air from the ramjet isolation section to the power generation combustor to drive the turbine to generate power.

[0029] The embodiment of the present invention is based on Figure 1 This architecture establishes a comprehensive energy system evaluation method based on the flight / engine coordinated control strategy. A specific implementation example is given below, which includes the following steps:

[0030] 1. Parameter initialization

[0031] Set the target required power and initial conditions (flight altitude, Mach, etc.) of the integrated energy system, divide the flight phase into segment points (Ma2, Ma5) based on the characteristics of the propulsion system, set constraints and control quantities, and give a reasonable initial parameter range.

[0032] 2. Aircraft Modeling

[0033] That is, the aircraft dynamics model is established, mainly considering the influence of the trajectory characteristics of accelerated climb and cruise in the vertical plane. Therefore, the aircraft can be regarded as a point mass model moving on the vertical plane. Based on the six-degree-of-freedom dynamics model of the aircraft, it is simplified according to the needs, and the state differential equations of various state parameters are established as follows:

[0034]

[0035] Where h is the flight altitude, V is the flight speed, γ is the climb angle, α is the flight attack angle, T is the thrust, D is the drag, L is the lift, and I sp represents specific impulse, m represents the mass of the aircraft, r represents the distance between the aircraft and the center of the earth, g represents the acceleration due to gravity, and the superscript represents the differential of the parameter.

[0036] The lift force L is defined as:

[0037] L=qSC L (α,Ma)

[0038] The resistance D is defined as:

[0039] D=qSC D(α,Ma)

[0040] Where q is the flight pressure, S is the reference wing area of ​​the aircraft, and the lift coefficient C is L and the drag coefficient C D Both are functions of the angle of attack α and the Mach number Ma.

[0041] 3. Engine Modeling

[0042] That is, a combined engine model is established, and the following simplified explanation is given during the calculation process of the model: Since the combined engine operates in the stratosphere and the atmospheric temperature is relatively constant, the unit flow thrust and specific impulse characteristics of the present invention only consider the influence of the Mach number, and do not consider the altitude and throttling characteristics for the time being.

[0043] 1. Axisymmetric intake duct model

[0044] According to the given incoming flow conditions and intake duct design parameters, the total intake air temperature T of the incoming flow is obtained. t0 and the total intake pressure P t0 , and the inlet air flow function q(λ). Since the energy extraction method of the present invention involves the extraction of incoming gas, the actual captured flow q of the intake duct is calculated according to the requirements of the engine design point:

[0045]

[0046] Among them, the air flow measurement constant K a =0.04042, flow capture coefficient Only the effect of Mach number is considered.

[0047] 2. Turbine engine working model

[0048] The turbine engine model consists of an axisymmetric central cone inlet, a turbine gas generator, and a tail nozzle. Since the turbine engine's operating speed range is Ma0 to 2.5, and there are cross-speed flights from subsonic to transonic, different flight conditions (subsonic, transonic, and supersonic) are modeled separately:

[0049] At subsonic and transonic speeds (Ma<1.1), the engine flow rate is determined by the demand of the gas generator, and the flow rate exceeding the demand is considered as overflow. Given the relative length L of the inlet duct center cone in,r and the total pressure loss coefficient of the intake duct, adjust the fuel-gas ratio f in the combustion chamber to make the main combustion chamber outlet temperature reach the highest value Then limit the relative conversion speed n cor,r , relative physical speed n r Determine the high pressure shaft speed n based on the critical nozzle throat area TH .

[0050] At supersonic speed (Ma≥1.1), the engine flow is mainly determined by the supersonic inlet. The inlet airflow of the gas generator mainly depends on the working state of the inlet and the flight conditions. Similarly, the fuel-air ratio f of the main combustion chamber makes the outlet temperature of the main combustion chamber reach the highest value. Combined with the determined high pressure shaft speed n H Calculate the final thrust T tur Specific impulse I sp,tur And high-pressure shaft power P C .

[0051] 3. Ramjet engine working model

[0052] Ramjet engines include two working modes: subsonic ramjet engines and scramjet engines. Their structure can be divided into several relatively independent major components based on the aerodynamic and thermodynamic processes: axisymmetric central cone inlet, subsonic / scramjet combustion chamber, and tail nozzle.

[0053] The thrust and specific impulse characteristics of a ramjet engine can be calculated by calculating the unit flow thrust and specific impulse characteristics. Since the wide-speed range combined ramjet engine operates in the stratosphere where the atmospheric temperature is relatively constant, its unit flow thrust and specific impulse characteristics only consider the influence of Mach number, and do not consider altitude and throttling characteristics for the time being.

[0054] Thrust per unit flow rate of ramjet engine F s / Specific Impulse I sp The fitting relationship is obtained according to the variation law of Mach number M0. Combined with the actual captured flow rate q of the inlet, the thrust and specific impulse of a single ramjet engine are:

[0055] T total =q·F s

[0056] I sp,total =q·I sp

[0057] 4. Energy System Modeling

[0058] That is, a comprehensive energy system model is established, and the following models are established accordingly based on the characteristics of different sub-components in the engine model:

[0059] 1. Turbine shaft power extraction model (Ma0~2, including Ma=2)

[0060] Following the existing turbine engine shaft power generation mode, when the turbine engine is working, a certain amount of power is extracted from the engine's high-pressure shaft, which is then driven by the transmission device to generate electricity for the electrical equipment on the aircraft.

[0061] P=P H,ext ·η

[0062] where η is the mechanical transmission and generator loss coefficient. The power balance equation in the turbo-engine model becomes

[0063] 2. Air turbo-generator model (Ma2~5, including Ma=5)

[0064] The air turbo-generator model internally bleeds air from the inlet duct of a ramjet engine, drives the turbine to expand and do work, and converts the energy through a generator, and finally discharges into the atmosphere.

[0065] The air bleed flow required for turbine work can be quantitatively analyzed by the following formula:

[0066]

[0067] where T t is the total temperature of the turbine inlet air, C p is the specific heat at constant pressure of the turbine inlet air, W T,cor is the turbine shaft power demand, η T is the turbine efficiency, (π T is the turbine pressure ratio, K g =1.33 is the specific heat ratio of the gas), and for the simplified turbine model, the present invention considers that the above turbine characteristic parameters only change with Mach number Ma.

[0068] The turbine work is mainly used for the operation of the power generation system and the transmission loss, so according to the power balance, the following equation is obtained:

[0069] P E = q2W T,cor η m

[0070] where P E is the power demand of the generator; q is the air flow; W T,cor is the turbine output power; and η m is the generator loss coefficient.

[0071] 3. Gas turbine generator model (Ma5~7)

[0072] The gas turbine generator model differs from the air turbine in that the air flow is first introduced into the combustion chamber to mix and burn with fuel, and then the gas is used to expand and do work. Therefore, in the power balance stage of the turbine expansion work model, the influence of the mixed fuel in the combustion chamber needs to be further considered, and the turbine output power is calculated as:

[0073] P E = (1+f) q2W t η m

[0074] Where f is the oil-gas ratio.

[0075] 5. Solving the Optimal Track

[0076] By using the Gaussian pseudo-spectral trajectory optimization method, the fuel consumption or range of the aircraft can be analyzed based on the optimal trajectory, thereby achieving a comprehensive evaluation of the combined power performance.

[0077] Based on the aircraft / propulsion system model, the state parameters are: flight altitude h, speed V, climb angle γ, aircraft mass m and angle of attack α; the control variable is: angle of attack change rate Throttle lever, etc. Among them, the rate of change of angle of attack As a control quantity, the purpose is to ensure a smooth flight. The state parameters between the endpoints of each flight phase (Ma0~2, Ma2~5, Ma5~7) should satisfy |x i -x i-1 |≤ε to ensure that the continuity of parameters in each stage is met.

[0078] Based on the aircraft control equations, the optimization problem of the climb trajectory can be expressed as a corresponding cost function and parameter constraints. The performance indicator of the present invention is to minimize the fuel consumption of the entire trajectory. The cost function is expressed as:

[0079]

[0080] Among them, t f Represents the end time, Represents the terminal vehicle weight, and the superscript (1) represents the climb segment. Given the boundary conditions and constraints, the minimum track dynamic pressure is limited to 10kPa and the maximum track dynamic pressure is limited to 75kPa. The initial mass of the aircraft m0 and the climb end mass m f Determined by different plans.

[0081] Finally, based on the optimal results, the influence of the call of the integrated energy system under the optimal trajectory on the overall performance of the combined power is output, and the evaluation of the integrated energy system based on the flight / engine coordinated control strategy is completed.

Claims

1. A comprehensive energy system evaluation method based on flight / engine coordinated control strategy, characterized by It includes the following steps: 1) Parameter initialization: Set the target required power and initial conditions, divide the flight stages into segmentation points in combination with the characteristics of the combined engine, set the constraint conditions and control variables, and give a reasonable range of initial parameters; 2) Establish the aircraft dynamics model: Considering the influence of the track characteristics in the vertical plane climbing section, regard the aircraft as a particle model moving on the vertical plane, simplify the six-degree-of-freedom model of the aircraft as required, and establish the state differential equations of various state parameters; 3) Establish the combined engine model: Under the flight conditions, establish the dynamics model of a typical TBCC engine, and finally use the angle of attack change rate and the TBCC throttle lever as control variables and combine them with the aircraft power model; The specific steps for establishing the combined engine model are as follows: (1) Establish the combined engine inlet model: Select an axisymmetric inlet, calculate the total pressure recovery coefficient, flow capture coefficient, drag coefficient and other performance parameters of the model according to the given inlet conditions and inlet design parameters, and obtain the outlet parameters of the inlet; (2) Establish the working model of the turbine engine: Calculate the air flow parameters at each section of the engine, the unit thrust, fuel consumption rate, specific impulse and other performance parameters of the engine through the working process parameters, and calculate the thrust of the turbine engine in combination with the captured air flow; (3) Establish the working model of the ramjet engine: The engine thrust and specific impulse are calculated through the unit flow thrust and specific impulse characteristics. Only consider the influence of Mach number, and temporarily do not consider altitude and throttling characteristics. The unit flow thrust and specific impulse can be obtained by modeling according to the known variation rules; 4) Establish the integrated energy system model: Establish three energy extraction modes for the flight speed range of Ma0 to 7 to be applicable to different working speed ranges; if 0 < Ma ≤ 2, the power generation mode of extracting shaft work from the high-pressure shaft of the turbine engine is adopted; if 2 < Ma ≤ 5, air is drawn from the outlet section of the inlet to drive an air turbine to generate electricity; if 5 < Ma ≤ 7, after air is drawn from the outlet section of the inlet, it is burned in the power generation combustion chamber and then drives a turbine to generate electricity; The establishment of the integrated energy system model is as follows: (1) Turbine shaft work extraction model: Extract a certain required power from the high-pressure shaft of the turbine engine and drive an electric generator through a transmission device; (2) Air turbine power generation model: Based on the total temperature, total pressure and flow rate of the oncoming flow at the outlet of the inlet, introduce the turbine working model to inversely solve the required target power to obtain the flow rate of the air to be drawn, and iteratively calculate the influence of the air extraction on the overall performance of the current combined ramjet engine; (3) Gas turbine power generation model: After the gas is drawn from the outlet of the inlet and burned in the combustion chamber, based on the total temperature, total pressure and flow rate of the gas, introduce the turbine working model to inversely solve the required target power to obtain the flow rate of the gas to be drawn, and limit the outlet total temperature to 2200K, and then iteratively calculate the influence of the air extraction on the overall performance of the current ramjet engine; 5) Solve the optimal trajectory: The optimal trajectory of the aircraft is solved based on the Gaussian pseudospectral method. In combination with the above model, the flight altitude, speed, climb angle, aircraft mass and angle of attack are set as state parameters, and the rate of change of angle of attack and TBCC throttle lever are set as control variables. The optimization problem of the climb trajectory is expressed as a corresponding cost function and parameter constraints, with minimum fuel consumption as the performance indicator. Based on the optimal result, the impact of the call of the integrated energy system under the optimal trajectory on the overall performance of the combined power is output, and the evaluation of the integrated energy system based on the flight / engine coordinated control strategy is completed.

2. The comprehensive energy system evaluation method based on the flight / engine coordinated control strategy according to claim 1 is characterized in that In step 1), the target required power and initial conditions are set, including flight altitude and Mach; the segmentation points are set to Ma2 and Ma5.

Images