Aerodynamic optimization design technology of the

Aero engine aerodynamic optimization design technology

the thrust and size of modern aircraft engines are getting larger and larger. In order to fully meet the development requirements, it is very difficult to expand the scale and size of simulation experiment equipment only, which can also be said to be difficult to do to a certain extent. As a special form of test, CFD technology can replace a considerable part of aero engine simulation test and reduce the test cost, Improve the quality of test data and test efficiency, and greatly shorten the test cycle of aeroengine development

cfd's advantages in engine design

engines have a decisive impact on aircraft performance. In view of the difficulty, high cost and long cycle of engine research and development, CFD technology came into being and developed rapidly in recent years. The application of CFD technology in the engine makes the detailed research on the aerodynamic characteristics of the engine a step forward, which not only saves the time and cost of engine test run, avoids the danger of actual test run, but also can obtain all parameter data, including parameters that are difficult to measure during actual test run, and can also solve the optimization problem of multiple parameters. With CFD software, the following functions can be achieved

(1) design, performance check, optimization and improvement of engine turbine, compressor and other components. Through CFD simulation test, the influence of geometric shape change on aerodynamic performance at design and off design points is analyzed quickly and systematically. In addition, numerical simulation and analysis can also be carried out for the data and phenomena obtained in the engine test run

(2) component integration. In the past, the full-scale simulation of engine is mostly zero dimensional, which can not reflect the objectively existing multi-component and multidisciplinary flow characteristics in the engine. The corresponding flow relationship can be obtained only after hardware tests. At this time, considerable research work has been carried out and a large number of tests have been done. The design changes will cause a huge waste of time and money. Using CFD technology, the integrated model of multiple components can be solved directly, which directly reflects the flow interference between components and the overall aerodynamic characteristics

(3) multi physical field coupling. The physical processes inside the engine involve many disciplines, and the accurate simulation of these processes must also include many disciplines. The traditional analysis method is carried out separately and orderly according to different classifications of disciplines. The characteristic of this method is that it takes a long time and often causes errors due to ignoring the strong coupling between disciplines. At present, the object of CFD analysis has expanded from a single component analysis based on two force columns measured with a dial indicator to a system level assembly simulation. At the same time, its analysis field is no longer limited to fluid mechanics, but now it has involved more abundant physical space, such as combustion, thermodynamics, multi field coupling and so on

to sum up, it is possible for people to carry out numerical simulation of the flow inside the engine with the help of computers. CFD method will replace the test to a certain extent, so as to reduce the cost and shorten the development cycle. In addition, numerical simulation can provide rich flow field information and provide a basis for designers to design and improve the engine

in order to adapt to the development strategy of aeroengine and meet the development needs of aeroengine, NUMECA company, with its strong R & D strength and more than ten years of rich engineering experience, not only has its corresponding fine/turbo numerical simulation analysis software and targeted theme modules for aeroengine, so that the numerical simulation analysis is closer to the real flow and provides more detailed flow field data for engine designers; In addition, NUMECA also has a groundbreaking and efficient software tool fine/design3d for three-dimensional blade design and optimization, which is unprecedented in all aspects. The software adopts the multi-objective parameter optimization method, and users can define multiple optimization objectives by themselves, while ensuring geometric and mechanical constraints, which provides a certain basis for designers to optimize and improve the engine

aerodynamic optimization design scheme

has enhanced the rapid development of domestic safety belt enterprises. As we all know, the characteristics of aeroengine flow field have very high requirements for the professionalism, calculation speed and accuracy of numerical simulation software. NUMECA adopts the most advanced and professional numerical simulation analysis and optimization design technology in the industry to ensure the accuracy of the simulation results and meet the needs of numerical simulation and optimization design analysis of the flow field of the core components of the engine. From domestic aero-engine research institutes to international aero-engine giants (GE, RR, Honeywell, etc.), from colleges and universities to enterprises and institutions, NUMECA software is the preferred CFD software in the industry

for the development research of aeroengine, NUMECA company has put forward complete solutions, including initial design, geometric modeling and geometric feature analysis, numerical simulation (lattice production, numerical solution, multi physical field problem analysis), optimization design, etc., as shown in Figure 1

aerodynamic optimization design concept

today's aero-engine has good performance, but its aerodynamic performance still has room for further improvement and improvement. Using optimization methods based on advanced mathematical theory for optimization design is an effective method. Fine/design3d has been considered as the most advanced software tool for 3D blade design and optimization of aeroengines. Fine/design3d, as the leader of 3D blade optimization design, provides a very fast and convenient way for the virtual network analysis of engine analysis and design by coupling the blade parametric modeling module autoblade with the numerical simulation analysis software package fine/turbo of NUMECA. As the optimization platform itself, a new intelligent optimization method with neural network, genetic algorithm and simulated annealing algorithm can realize multi-objective and multi parameter optimization functions. Users can define multiple optimization objectives by themselves, and ensure geometric and mechanical constraints at the same time. The optimization process is shown in Figure 2

autoblade is a general geometric modeling tool for compressor and turbine blades and channels. The geometric definition parameters are universal (pressure surface/suction surface profile or mid arc/blade thickness, etc.) and highly flexible (independent control of tangential and meridional tilt and sweep, three-dimensional stacking mode of multiple blades, inlet and outlet edge types of multiple splitter blades, circular arc or multiple cutting section forms, etc.). The calculation functions of throat area and position, moment of inertia, center of gravity position, blade profile curvature and thickness distribution are embedded in two-dimensional and three-dimensional

autoblade, as a professional blade parametric modeling tool, includes the following functions

(1) parametric geometric templates for axial flow, centrifugal compressors, turbines, fans and other machinery

(2) a variety of end wall profile types, such as B-spline curve, Bezier curve, straight line Bezier curve straight line combination line, straight line spline straight line combination line, user-defined linetype, etc

(3) a variety of flow surface structures make it impossible for the experimental machine to model, such as linear interpolation for the plane, cylindrical surface, conical surface, hub and wheel cover of axial flow or runoff respectively

(4) various stacking laws of blades, such as the stacking at any position of leading edge point, center of gravity, maximum thickness point, midpoint of throat line of blade shape, tail edge point, middle arc or chord line

(5) various types of front and rear edge curves defined by blade meridian positions, such as straight lines, Bezier curves with adjustable control points, and B curves with adjustable control points

(6) the types of stacking lines defined by various impeller circumferential positions, such as straight lines, Bezier curves and combination lines of straight lines, simple Bezier curves, Bezier curves with adjustable control points, and B-spline curves with adjustable control points

autoblade provides convenient design ideas and ways for engine R & D and designers with professional modeling functions and processes

autoblade can also analyze the geometric characteristics of the designed model, including the angle change of the end wall profile, the curvature change of the end wall profile, the thickness distribution, the angle change of the middle arc, the curvature change of the middle arc, the angle change of the pressure surface and the suction surface, the curvature change of the pressure surface and the suction surface, and the channel width change, which provides convenient conditions for the designer to analyze and check the model

aerodynamic optimization design application

figure 3~4 shows the optimization design results of NUMECA for the core components of aeroengine respectively. The optimization process integrates parametric modeling, numerical simulation analysis and optimization design software, and obtains products that meet the requirements of designers

Figure 3 shows a comparison diagram of three-dimensional optimal design of a compressor. The aerodynamic shape of the blade is optimized to improve the aerodynamic performance of the compressor. The figure shows the changes of aerodynamic performance and working range before and after blade optimization. It can be seen that the aerodynamic performance is significantly improved, and the working range of the compressor is also significantly broadened

Figure 4 is a comparison diagram of aerodynamic shape and performance after optimized design of a turbine. It can be seen from the figure that under the given constraints, by changing the aerodynamic shape of the turbine blade, the polyurethane exterior wall insulation material is gradually accepted by the market with its good performance, and the aerodynamic performance is greatly improved

the optimization of the model given in Figure 5 is divided into two steps. In the first step, only aerodynamic optimization is carried out without considering the strength factor. The second step is to optimize the aerodynamic strength coupling. Figure 5 shows the comparison of stress distribution of blades before and after optimization. It can be seen from the figure that the aerodynamic performance of scheme I, such as blocking flow, efficiency and surge margin, has been improved, but the maximum stress on the blade has increased because the strength factor is not considered. The aerodynamic strength coupling optimization is carried out in scheme 2, and the aerodynamic performance such as blocking flow, efficiency and surge margin are also improved. Although the aerodynamic performance is not as excellent as that of scheme 1, the maximum stress of the blade does not increase, meeting the strength requirements

conclusion

CFD technology, which is widely used in the research and development process of aeroengine, not only greatly shortens the research and design cycle of the engine and reduces the design cost, but also provides detailed flow field data information for R & D designers, which further improves the aerodynamic performance of the engine, improves efficiency, widens the working range, and makes the flow field distribution more reasonable