The hottest turboshaft engine combined compressor

Development of parametric simulation system for turboshaft engine combined compressor rotor based on ANSYS

1 preface

parametric design is a mathematical method to solve the problem of design constraints. It uses a group of parameters to agree the relationship of dimensions when the structural shape is more finalized, and then changes the structural shape through size drive. Parametric design is widely used in the modeling of different types of experimental machines for mechanical products. In recent years, the idea of parameterization has been integrated into finite element analysis, and a finite element analysis based on structural parameterization has been proposed. However, because only the geometric model can be parameterized, the degree of parameterization is relatively shallow. Therefore, a fully parameter driven finite element analysis method is proposed, which parameterizes the pre-processing and post-processing of finite element analysis, including the parameterization of geometric models, finite element lattice division, constrained boundary conditions, loads, material properties, element types, analysis types and post-processing types. It has a high degree of automation and has a bright future

ansys is one of the few finite element analysis software supporting parametric design at present. ANSYS has powerful functions, good versatility, and good openness. Users can develop a special system with industry analysis characteristics on its standard version according to specific needs. ANSYS provides three secondary development tools: parametric programming language (APDL), through which the parametric finite element analysis program is compiled to realize the full parametric drive of the finite element analysis process; User interface design language (UIDL), through which ANSYS graphical interface is written or modified to make it more in line with the characteristics of industry analysis; User program features (UPFs), through which the functions of ANSYS can be extended from the level of developing program source code. The core content of the parametric finite element analysis system of turboshaft engine combined compressor rotor in this paper is the definition of parametric model and the compilation of finite element analysis program with variable parameters. Then the system operation interface is developed by using UIDL language, and the parametric finite element program of various parts is integrated into ANSYS environment

2 structural and design characteristics of turboshaft engine compressor

turboshaft engine is a turbojet engine that outputs shaft power. France was the first country to develop turboshaft engines. In the early 1950s, Turbomeca developed the world's first aviation turbine shaft engine, which was named "adost-l". The compressor structure of turboshaft engine ranges from pure axial-flow, single-stage centrifugal, two-stage centrifugal to combined axial-flow and centrifugal compressors. At present, most turboshaft engines of helicopters use a combined compressor composed of several stages of axial flow and one stage of centrifugation. For example, domestic turboshaft 6 and turboshaft 8 engines; T700 engine on "Black Hawk" helicopter. The axial compressor of turboshaft engine adopts a large number of integral structures, with simple structure and a small number of components. For example, the rotor blade and disc are made into one to form a disc structure. The French achye engine and the American T700 engine all adopt the integral disc structure

the design process of compressor is a process of repeated correction, coordination, calculation and experiment of aerodynamic design and structural design. From the flow chart of compressor aerodynamic and structural design [6], it can be seen that there are a lot of structural strength analysis in both processes. In addition, it can be seen from the flow chart that there is a lot of repeatability in the design process. As a complex system of aero-engine compressor rotor, if every structural design adjustment and structural strength analysis is a new process, the amount of repeated labor will be very huge. Therefore, we introduce the parametric design and analysis method into the design process of turboshaft engine combined compressor, so that the design and analysis work is mainly the selection of structural forms of various parts, the adjustment of specific parameters, and the structural strength analysis of each design scheme. This can reduce the workload of the staff and shorten the design cycle of the compressor

3 definition of parametric finite element analysis model

for the complex non-standard part of turboshaft engine combined compressor, we first decompose its structure, which can be divided into axial flow disc, axial flow blade, centrifugal disc and centrifugal blade. We know that the structure of the blade disc is very complex, and it is difficult to define the geometric parameters. Therefore, we introduce the concept of the characteristic structure of the installed capacity of domestic power batteries of about 33.55gwh, and define the parameters according to the characteristic structure. Through the feature analysis of the blade disc structure, various forms of wheel discs have three basic features: rim, web and hub, which are called base disc, and the other shapes are auxiliary features, including flange, drum, shaft diameter, mounting edge, evenly distributed holes or mounting holes, ring groove and grate teeth [7]. Based on this idea, we study the structure of an axial-flow bladed disc (Fig. 1), appropriately simplify the structure and extract the geometric parameters of the structure under the condition that the analysis requirements are met (Table 1)

Figure 1 structural diagram of an axial-flow bladed disc

Table 1 structural characteristic parameters table

Table 2 finite element analysis parameters table

4 APDL parametric finite element analysis method

ANSYS parametric finite element analysis program design method and steps:

(1) using parametric design ideas, abstract the characteristic parameters describing the model according to the geometric structure of the model, and appropriately simplify the actual model without affecting the accuracy. At the same time, set finite element analysis parameters such as element type, cell accuracy, material parameters, etc

(2) the finite element analysis program including solid modeling, analysis process and result processing process is compiled in APDL language

(3) introduce design analysis parameters to form a finite element analysis program with variable parameters

(4) according to the design analysis requirements, the parameters are given specific eigenvalues for finite element analysis

Figure 2 parameterized finite element design and analysis process

in this way, new results can be obtained continuously by repeating (4) during structural design and analysis. For specific users, finite element analysis results can be obtained without even knowing the specific analysis process and method of finite element. In addition, according to the design requirements, we can add various analysis functions and post-processing functions, or develop new functional modules to integrate with ANSYS, such as developing new optimization algorithm programs

5 turboshaft engine combined compressor parametric simulation example

in the parametric design and analysis of complex parts, first, the complex parts are decomposed according to characteristics; Then, the module assembly relationship is introduced as a constraint to establish the functional relationship between component parameters, so as to realize the parametric design and analysis of complex 3D component solid model. Based on the above ideas, we realize the parametric simulation of the turboshaft engine combined compressor rotor, which is composed of three-stage axial flow and one-stage centrifugal disks

Figure 3 system interface developed by UIDL

Figure 4 finite element analysis model of axial flow blade

Figure 5 parameterized finite element analysis model of axial flow disk

Figure 6 parameterized finite element analysis model of axial flow disk

Figure 7 parameterized finite element analysis equivalent stress of axial flow disk

figure 8 parameterized finite element analysis model of combined compressor rotor

Figure 9 parameterized finite element analysis equivalent stress

6 conclusion

(1)the The parametric design idea is introduced into the design and analysis of the integral blade disc of the turboshaft engine combined compressor. The designer only needs to adjust the specific structural parameters and finite element analysis parameters each time to carry out the finite element calculation. Without repeated modeling, a lot of time is saved and the design cycle of the combined compressor can be shortened

(2) the introduction of parametric design idea enables designers to conduct finite element analysis of each substructure according to the design requirements, such as finite element analysis of blades at all levels, discs at all levels, discs at all levels, etc

(3) based on structural parameterization, designers can easily carry out 2d/3d optimization design of structures

(4) with the enrichment of our parametric model library of bladed disks of various structural forms, designers only need to select a certain structure according to the design requirements and adjust the parameters, which can be combined into the whole compressor for analysis. It is a topic worthy of concern to realize the semi automation of design analysis

references

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[6] Aeroengine Design Manual (compressor volume) Beijing: Aviation Industry Press, 2000

[7] Ma Mei et al Modeling and analysis of bladed disk structure based on constraints in concurrent engineering environment [j] Journal of Aeronautical dynamics, 1998.10 (end)