Variable cycle / self-adaptive engine performance design method based on core engine derivation

Abstract

The invention discloses a variable cycle / self-adaptive engine performance design method based on core engine derivation. The method comprises the following steps that S1, a basic small-bypass-ratio turbofan engine derives three types of different design parameters with different engine active values; s2, after different design parameters are actively selected, respective core machine matching parameters are determined; s3, determining respective iteration value design parameters and derived design constraint conditions after determining respective core machine matching parameters; s4, performing iterative solution by using a Newton-Raphson method; s5, if the iterative solution is successful, establishing a simulation performance model of each derivative engine, and carrying out corresponding overall performance simulation calculation; and S6, if the iterative solution fails, returning to the step S1 and the step S2 to readjust the active value design parameters and the core machine matching parameters. By the adoption of the variable cycle / self-adaptive engine performance design method based on core engine derivation, good performance characteristics are shown, and the expected effect is met.

Description

Technical Field

[0001] The present invention relates to the technical field of core engines, and in particular to a variable cycle / adaptive engine performance design method based on core engine derivation. Background Art

[0002] The adaptive cycle engine is one of the important candidates for the power plant of future advanced fighter jets. Through mode switching, it can have the performance characteristics of high thrust and low fuel consumption, thus meeting the complex mission requirements of future fighter jets. However, the high R&D cost is contradictory to the significant performance advantage. According to the survey, the development cost of the F100 engine installed on the F15 and F16 is 1.41 billion US dollars, and the development cost of the F135, the world's most advanced engine, is as high as 13.605 billion US dollars. For adaptive cycle engines with more complex structures and more new technologies, their development costs will rise further, so it will be difficult for countries to support the comprehensive development of adaptive cycle engines of multiple configurations at the same time.

[0003] In order to achieve low-cost design and development of engines, the world's aviation powers have proposed a design concept of universal core engine derivatives. Its essence is to match different low-pressure systems for the gas generator composed of compressors, combustion chambers and turbines to derive engines with different configurations and performances. This design model can inherit existing mature technologies, improve the reliability, durability and maintainability of the core engine, enable advanced technologies to be verified and matured in engine products in advance, and quickly respond to different mission requirements to form products. Ultimately, it can meet the performance requirements of the engine while reducing the cost and cycle of engine research and development.

[0004] Compared with foreign countries, China's industrial foundation is weak, and the core engine design research started late. From 1980 to 1994, benchmarking the F404 engine, my country completed the test of the turbofan engine core with a thrust-to-weight ratio of 8. In 1990, in order to meet the power unit requirements of the fourth-generation fighter, my country carried out the design and development of a core engine with a thrust-to-weight ratio of 10. By the beginning of the 21st century, the Sichuan Turbine Research Institute had carried out the design planning of a general core engine of 5kg / s-30kg / s, and the derived engine thrust covered 200daN-20000daN. Later, the Turbine Research Institute derived the design and research work of a 10kN thrust-class medium bypass ratio turbofan engine based on a 5kN thrust-class turbofan engine. Since 2003, the Hunan Power Machinery Research Institute has carried out the demonstration and development of 4kg / s flow rate general core engine derived turboshafts, turboprops, turbofans and gas turbines. The 1000kW-class civil turboshaft engine derived from it has completed the whole machine performance and main life scientific research tests, and is currently carrying out airworthiness certification tests. In terms of core engine design research progress, Beijing University of Aeronautics and Astronautics has established a core engine derivative design process, analyzed the positioning principle of the core engine working point, the matching mechanism of the high and low pressure systems, and combined with the engine size and weight estimation method to optimize the performance of the derived engine.

[0005] The above studies all take conventional turbojet, turbofan and turboshaft engines as research objects, and carry out core engine derivative design research, but lack the core engine derivative design method suitable for variable cycle / adaptive engine. The goal of this patent is to apply the core engine derivative design concept to the performance design research of variable cycle / adaptive cycle engines, and solve the contradiction between the performance advantage and R&D cost of adaptive cycle engines. On the other hand, the conventional core engine derivative design is usually based on a fixed core engine. Due to the limited performance of the original core engine, the improvement of the performance of the derivative engine is limited. For example, due to the low design pressure ratio of the original core compressor facing the subsonic economic transport mission, the further increase of the bypass ratio of the turbofan engine is restricted; and the design pressure ratio is too high for the supersonic maneuverability mission, resulting in insufficient cycle heating. It can be inferred from this that if the pressure ratio and air flow can be adaptively improved and adjusted based on the original core engine according to different mission requirements, the design of more types of engines will be successfully realized, and a variety of tasks with a larger flight speed range will be better adapted. Summary of the invention

[0006] The purpose of the present invention is to provide a variable cycle / adaptive engine performance design method based on core engine derivation. The derivative design after adaptive improvement of the original core engine can improve the performance level and adaptability of the core engine, broaden the application scope of the core engine, and enable it to meet the matching requirements of adaptive variable cycle / adaptive engines and meet the use requirements of different types of flight missions. The simulation calculation results show that the various series of engines derived from the design method proposed in this patent have shown good performance characteristics under specified subsonic and supersonic flight conditions, which is in line with the expected effect.

[0007] The present invention provides a variable cycle / adaptive engine performance design method based on core engine derivation, comprising the following steps: S1, first, in the derivation process, a basic small bypass ratio turbofan engine derives three different types of engines to actively take different design parameters;

[0008] S2. After actively selecting different design parameters, determine the core engine matching parameters;

[0009] S3. After determining the core engine matching parameters, determine the iterative value design parameters and derived design constraints;

[0010] S4, using the Newton-Raphson method to iteratively solve;

[0011] S4.1, Initialization: Select the initial iterative design value;

[0012] S4.2, iterative update: calculate the Jacobian matrix and the equilibrium residual of the current point, and solve the linear equations to obtain the increment;

[0013] S4.3, update iteration variables;

[0014] S4.4, judging convergence: check whether the equilibrium residual is less than the set tolerance value. If it is satisfied, the iterative solution is considered successful;

[0015] S4.5, non-convergence processing: If it does not converge and does not exceed the set upper limit of the iteration step, return to step S4.2 to continue the iteration; if it does not converge and reaches the upper limit of the iteration step, the Newton-Raphson iteration solution fails;

[0016] S5. If the iterative solution is successful, a simulation performance model of each derived engine is established, and corresponding overall performance simulation calculation is carried out;

[0017] S6. If the iterative solution fails, it is necessary to return to step S1 and step S2 to readjust the active value design parameters and the core engine matching parameters, and perform the iterative solution again.

[0018] Preferably, in step S1, the three different types of engines include a high bypass ratio turbofan engine, a dual bypass variable cycle engine and a triple bypass adaptive engine.

[0019] Preferably, in step S1, the design parameters of the basic small bypass ratio engine include flight altitude, flight speed, air flow, bypass ratio, fan pressure ratio, core compressor pressure ratio, and turbine inlet temperature.

[0020] Preferably, in step S1, the design parameters of the high bypass ratio turbofan engine include flight altitude, flight speed, air flow, overall bypass ratio, fan pressure ratio, boost stage pressure ratio, core engine new inlet stage pressure ratio, high-pressure turbine guide vane relative flow area, and external / internal tail nozzle outlet airflow velocity ratio.

[0021] Preferably, in step S1, the design parameters of the dual-external variable cycle engine include flight altitude, flight speed, air flow, first diversion ratio, second diversion ratio, fan pressure ratio, CDFS pressure ratio, and relative flow area of ​​the high-pressure turbine guide vane.

[0022] Preferably, in step S1, the design parameters of the three-outer-tube adaptive engine include flight altitude, flight speed, air flow, first diversion ratio, second diversion ratio, third diversion ratio, front fan pressure ratio, rear fan pressure ratio, CDFS pressure ratio, pressure ratio of the newly added inlet stage of the core engine, relative flow area of ​​the high-pressure turbine guide vane, and outer / inner tail nozzle outlet airflow velocity ratio.

[0023] Therefore, the present invention adopts the above-mentioned variable cycle / adaptive engine performance design method based on core engine derivation, and the derivative design after adaptive improvement of the original core engine can improve the performance level and adaptability of the core engine, broaden the application scope of the core engine, and enable it to meet the matching requirements of adaptive variable cycle / adaptive engines and meet the use requirements of different types of flight missions. The simulation calculation results show that the various series of engines derived from the design method proposed in this patent have shown good performance characteristics under the specified subsonic and supersonic flight conditions, which meets the expected effect.

[0024] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of a low bypass ratio turbofan engine and a high bypass ratio turbofan engine according to a core engine derived variable cycle / adaptive engine performance design method of the present invention;

[0026] Figure 2 A schematic diagram of a low bypass ratio turbofan engine and a variable cycle engine structure according to a core engine derived variable cycle / adaptive engine performance design method of the present invention;

[0027] Figure 3 A schematic diagram of a low bypass ratio turbofan engine and an adaptive engine structure based on a core engine derived variable cycle / adaptive engine performance design method of the present invention;

[0028] Figure 4 A derived design roadmap of a core engine-derived variable cycle / adaptive engine performance design method of the present invention;

[0029] Figure 5 The invention provides a variable cycle / adaptive engine performance design method based on core engine derivative for designing high bypass ratio turbofan engine design parameters, constraint conditions and matching parameters;

[0030] Figure 6 The invention provides a variable cycle / adaptive engine performance design method based on a core engine derived variable cycle / adaptive engine design parameter, constraint conditions and matching parameters of the derived variable cycle engine;

[0031] Figure 7 The invention provides design parameters, constraints and matching parameters of a derived adaptive engine according to a core engine-derived variable cycle / adaptive engine performance design method;

[0032] Figure 8 The present invention provides a comparison of unit thrust-fuel consumption rate under subsonic conditions based on a core engine-derived variable cycle / adaptive engine performance design method;

[0033] Fig. 9 The present invention provides a supersonic condition unit thrust-fuel consumption comparison of a core engine-derived variable cycle / adaptive engine performance design method;

[0034] Fig.10 The present invention is an overall flow chart of a variable cycle / adaptive engine performance design method based on core engine derivation. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0036] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0037] The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprises" and similar terms mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0038] Embodiment 1

[0039] like Figure 1-Figure 10 As shown, the present invention provides a variable cycle / adaptive engine performance design method based on core engine derivation, comprising the following steps:

[0040] S1. The basic low bypass ratio turbofan engine derives three different types of engines with different active design parameters;

[0041] S2. After actively selecting different design parameters, determine the core engine matching parameters;

[0042] S3. After determining the core engine matching parameters, determine the iterative value design parameters and derived design constraints;

[0043] S4, using the Newton-Raphson method to iteratively solve;

[0044] The specific algorithm steps are as follows:

[0045] S4.1. Initialization: Selecting initial iterative design values

[0046] S4.2, Iterative update: For each step k, calculate the Jacobian matrix and the equilibrium residual of the current point And solve the linear system of equations Thus, the increment

[0047] S4.3. Update iteration variables: Use Updates the iteration variable.

[0048] S4.4. Judging convergence: Checking balanced residuals Is it less than the set tolerance value (usually 0.00001)? If it is satisfied, the iterative solution is considered successful.

[0049] S4.5, non-convergence processing: If it does not converge and does not exceed the set upper limit of the iteration step (generally 400), return to step S2 to continue iterating; if it does not converge and reaches the upper limit of the iteration step, it is considered that the Newton-Raphson iteration solution has failed.

[0050] The Newton-Raphson method is based on Taylor expansion and finds the solution of a nonlinear system of equations by linearizing its approximation. The basic idea is to construct a linear equation at the current point using the function value and derivative value at that point, so as to solve the next iteration point until the solution converges.

[0051] The solution to the derived design problem can be abstracted into a nonlinear system of equations in the following form:

[0052]

[0053] Among them, f represents the core engine derived design model; is a vector of iterative design parameters; its goal is to make the balanced residual representing the derived constraints is 0.

[0054] Through Taylor expansion we can get:

[0055]

[0056] in yes exist The Jacobian matrix (i.e. derivative matrix) of a point is defined as:

[0057] Will

[0058] Substituting into Taylor expansion, we can get

[0059]

[0060] Therefore, the iterative formula can be obtained:

[0061]

[0062] The iteration step is updated as:

[0063]

[0064] S5. If the iterative solution is successful, a simulation performance model of each derived engine is established, and corresponding overall performance simulation calculation is carried out;

[0065] S6. If the iterative solution fails, it is necessary to return to step S1 and step S2 to readjust the active value design parameters and the core engine matching parameters, and perform the iterative solution again.

[0066] Using a basic small bypass ratio engine, a high bypass ratio turbofan engine, a dual-bypass variable cycle engine and a triple-bypass adaptive engine are derived respectively. During the derivation process, the core engine is improved accordingly to adapt to the requirements of the derived engine configuration for cycle parameters.

[0067] In terms of core engine control parameters, adjusting the compressor guide vanes can reduce the compressor front stage pressure ratio at low conversion speed, thereby avoiding stall. The adjustment of the compressor guide vanes can also affect the core duct air flow, thereby matching the airflow distribution requirements of different working modes of the variable cycle engine. In the overall modeling process, the performance of the compressor with independent adjustable guide vanes is characterized by a three-dimensional characteristic diagram (guide vane angle, conversion speed, and relative position R of the compressor operating point). Adjusting the core engine turbine guide vane area under different types of engine derived design points can better decouple the two key parameters of the core compressor working state and the turbine front temperature, and is expected to control the high-pressure turbine to achieve a more ideal pressure drop ratio and efficiency. Reasonable design of the physical speed of the core engine can ensure the safety of the core engine structure from the overall level, and can also achieve the decoupling of the low-pressure compression system pressure ratio and the core engine conversion speed. The control parameters of the core engine are shown in the following table.

[0068] Table 1 Core engine control parameters

[0069]

[0070]

[0071] The design parameters of various types of engines are shown in Table 2-5. In order to directly compare the performance levels of the designed series engines under specific flight conditions,

[0072] In step S1, the three different types of engines include a high bypass ratio turbofan engine, a dual bypass variable cycle engine and a triple bypass adaptive engine.

[0073] In step S1, the design parameters of the basic low bypass ratio engine include flight altitude, flight speed, air flow, bypass ratio, fan pressure ratio, core compressor pressure ratio, and turbine inlet temperature.

[0074] In step S1, the design parameters of the high bypass ratio turbofan engine include flight altitude, flight speed, air flow, overall bypass ratio, fan pressure ratio, boost stage pressure ratio, core engine newly added inlet stage pressure ratio, high-pressure turbine guide vane relative flow area, and external / internal tail nozzle outlet airflow velocity ratio.

[0075] In step S1, the design parameters of the dual-external variable cycle engine include flight altitude, flight speed, air flow, first diversion ratio (after CDFS), second diversion ratio (after fan), fan pressure ratio, CDFS pressure ratio, and relative flow area of ​​the high-pressure turbine guide vane.

[0076] In step S1, the design parameters of the three-outer-tube adaptive engine include flight altitude, flight speed, air flow, the first diversion ratio (after CDFS), the second diversion ratio (after the rear fan), the third diversion ratio (after the front fan), the front fan pressure ratio, the rear fan pressure ratio, the CDFS pressure ratio, the pressure ratio of the newly added inlet stage of the core engine, the relative flow area of ​​the high-pressure turbine guide vane, and the outer / inner tail nozzle outlet airflow velocity ratio.

[0077] Typical operating conditions of subsonic cruise and supersonic cruise were selected as the test environment, and performance tests were carried out on each engine simultaneously.

[0078] Table 2 Basic low bypass ratio turbofan engine design parameters

[0079]

[0080] Table 3 Derived high bypass ratio turbofan engine design parameters

[0081]

[0082] Table 4 Design parameters of derived variable cycle engine

[0083]

[0084]

[0085] Table 5 Derived adaptive engine design parameters

[0086]

[0087] Figure 8 The chart shows the unit thrust-fuel consumption characteristics of the four series engines at high altitude subsonic flight (11km, Mach 0.8). It can be seen from the figure that except for the high bypass ratio turbofan engine with its lower unit thrust and fuel consumption, which is located on the lower left side of the comparison chart, the other three engines all show the characteristics of high unit thrust and high fuel consumption. Among these three engines, the basic low-bypass turbofan engine has a relatively small unit thrust and a narrow thrust adjustment range, and its fuel consumption rate is also the highest under the same unit thrust conditions; the adaptive engine can achieve the highest un-afterburning unit thrust, the widest thrust adjustment range, and maintain the lowest fuel consumption rate by switching the working mode, which shows that it has the best applicability for subsonic high-maneuverability and high-stealth missions; the dual-bypass variable cycle engine can achieve a thrust level close to that of the triple-bypass adaptive engine by adjusting the working mode, but its fuel consumption rate is higher than that of the triple-bypass adaptive engine. It can be seen that its performance is slightly inferior to that of the triple-bypass adaptive engine under subsonic cruise conditions, but it still shows a significant performance advantage compared to the low-bypass turbofan engine.

[0088] Fig. 9 The unit thrust-fuel consumption characteristics of three engines, namely, low bypass ratio turbofan, variable cycle and adaptive, are shown under high-altitude supersonic flight conditions (11km, Mach1.5). It can be observed from the figure that when the flight speed reaches the medium and low supersonic range, the adaptive engine with a higher bypass ratio has a fuel consumption advantage only in the low unit thrust range, while its maximum non-afterburning unit thrust and thrust adjustable range are inferior to those of the low bypass ratio turbofan and variable cycle engines, indicating that it is not suitable for supersonic high maneuverability missions; the variable cycle engine shows the largest non-afterburning unit thrust and the widest thrust adjustment range, and has a better fuel consumption than the low bypass ratio turbofan engine in the entire thrust range. It can be seen that when the flight speed gradually increases, it has entered the advantageous working range of the double external bypass variable cycle.

[0089] Therefore, the present invention adopts the above-mentioned variable cycle / adaptive engine performance design method based on core engine derivation, and the derivative design after adaptive improvement of the original core engine can improve the performance level and adaptability of the core engine, broaden the application scope of the core engine, and enable it to meet the matching requirements of adaptive variable cycle / adaptive engines and meet the use requirements of different types of flight missions. The simulation calculation results show that the various series of engines derived from the design method proposed in this patent have shown good performance characteristics under the specified subsonic and supersonic flight conditions, which meets the expected effect.

[0090] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A variable cycle / adaptive engine performance design method based on core engine derivation, characterized in that: The following steps are involved: S1. First, in the derivation process, the basic low bypass ratio turbofan engine derives three different types of engines and actively takes different design parameters; S2. After actively selecting different design parameters, determine the core engine matching parameters; S3. After determining the core engine matching parameters, determine the iterative value design parameters and derived design constraints; S4, using the Newton-Raphson method to iteratively solve; S4.1, Initialization: Select the initial iterative design value; S4.2, iterative update: calculate the Jacobian matrix and the equilibrium residual of the current point, and solve the linear equations to obtain the increment; S4.3, update iteration variables; S4.4, judging convergence: check whether the equilibrium residual is less than the set tolerance value. If it is satisfied, the iterative solution is considered successful; S4.5, non-convergence processing: If it does not converge and does not exceed the set upper limit of the iteration step, return to step S4.2 to continue the iteration; If it does not converge and reaches the upper limit of the iteration step, the Newton-Raphson iteration solution fails; S5. If the iterative solution is successful, a simulation performance model of each derived engine is established, and corresponding overall performance simulation calculation is carried out; S6. If the iterative solution fails, it is necessary to return to step S1 and step S2 to readjust the active value design parameters and the core engine matching parameters, and perform the iterative solution again.

2. A core engine derived variable cycle / adaptive engine performance design method according to claim 1, characterized in that: In step S1, the three different types of engines include a high bypass ratio turbofan engine, a dual bypass variable cycle engine and a triple bypass adaptive engine.

3. The variable cycle / adaptive engine performance design method based on core engine derivation according to claim 1 is characterized in that: In step S1, the design parameters of the basic low bypass ratio engine include flight altitude, flight speed, air flow, bypass ratio, fan pressure ratio, core compressor pressure ratio, and turbine inlet temperature.

4. The variable cycle / adaptive engine performance design method based on core engine derivation according to claim 1 is characterized in that: In step S1, the design parameters of the high bypass ratio turbofan engine include flight altitude, flight speed, air flow, overall bypass ratio, fan pressure ratio, boost stage pressure ratio, core engine newly added inlet stage pressure ratio, high-pressure turbine guide vane relative flow area, and external / internal tail nozzle outlet airflow velocity ratio.

5. The variable cycle / adaptive engine performance design method based on core engine derivation according to claim 1 is characterized in that: In step S1, the design parameters of the dual-external variable cycle engine include flight altitude, flight speed, air flow, first split ratio, second split ratio, fan pressure ratio, CDFS pressure ratio, and high-pressure turbine guide vane relative flow area.

6. The variable cycle / adaptive engine performance design method based on core engine derivation according to claim 1 is characterized in that: In step S1, the design parameters of the three-outer-tube adaptive engine include flight altitude, flight speed, air flow, first diversion ratio, second diversion ratio, third diversion ratio, front fan pressure ratio, rear fan pressure ratio, CDFS pressure ratio, core engine newly added inlet stage pressure ratio, high-pressure turbine guide vane relative flow area, and outer / inner tail nozzle outlet airflow velocity ratio.

Images