涡轮作为航空发动机核心机的重要组成部分，其性能对发动机的整机性能有极大的影响。对转涡轮技术作为能有效提高发动机的功率密度，减少陀螺力矩的有效手段，在近年来有了较大的发展，但高负荷的对转涡轮设计难度较大，在工程应用中仍然面临着巨大挑战。本文介绍了轴流涡轮的工作原理，从叶片机中遵循的基本方程到基元级的速度三角形。介绍了气动设计的基本参数及其取值所要考虑的因素，如载荷系数、反力度、流量系数和轴向速比系数。介绍并编写了涡轮级参数一维优化程序，该程序在总体下达的参数下，可以通过该程序寻找最优参数从而确定速度三角形、子午流道的大小和形状，以得出三维设计参数的参考。本文的对转涡轮是为了匹配一款高压比离心压气机而设计的，其总体下达的参数为：进口总压1.3MPa，进口总温1700K，总压比11.7，流量4.91kg/s。在优化程序的基础上，进行了两级涡轮的一维气动设计，在等中径设计的基础上计算出从入口到出口各个流动截面上的热力参数，从而确定子午流道的基本尺寸，并通过简化径向平衡方程的等环量规律确定叶片的扭向规律。在确定叶片扭向规律和不同叶高上的速度三角形参数后，参照工程手册和同类型涡轮的数据，以Pritchard11参数化造型方法对叶栅进行造型，以重心积叠规律将叶栅三维成型，得出两级涡轮的三维几何文件。通过NUMECA进行数值计算并进行流场分析，给出了该涡轮气流角对于出功比的影响，调节了两级涡轮的输出功率，以此作为设计的原型机。考虑到参数化叶片造型中存在的不足，对叶栅造型对两级涡轮性能及流动的影响进行分析，主要分析了后弯角、前缘形状和叶片弯的影响。本文设计的对转涡轮流量为4.91kg/s，效率为88.14%。
As an important component of the core machine of aero engines, the performance of turbines has a great impact on the overall performance of the engine. The counter rotating turbine technology, as an effective means to improve the power density of the engine and reduce the gyroscopic torque, has made significant progress in recent years. However, the design of high load counter rotating turbines is difficult and still faces huge challenges in engineering applications.This paper introduces the working principle of axial flow turbines, from the basic equations followed in blade machines to the velocity triangles of the elementary stage. Introduced the basic parameters of aerodynamic design and the factors to be considered for their values, such as load coefficient, reaction degree, flow coefficient, and axial speed ratio coefficient. Introduced and written a one-dimensional optimization program for turbine stage parameters. Under the overall assigned parameters, this program can be used to find the optimal parameters and determine the size and shape of the velocity triangle and meridional flow channel, in order to obtain a reference for three-dimensional design parameters. The counter rotating turbine in this paper is designed to match a high-pressure ratio centrifugal compressor. The overall parameters assigned are: total inlet pressure of 1.3MPa, total inlet temperature of 1700K, total pressure ratio of 11.7, and flow rate of 4.91kg/s.On the basis of optimizing the program, a one-dimensional aerodynamic design of a two-stage turbine was carried out. Based on the equal pitch diameter design, the thermodynamic parameters of each flow section from the inlet to the outlet were calculated to determine the basic size of the meridional flow channel. The torsional law of the blades was determined by simplifying the equal circulation law of the radial balance equation. After determining the blade twist law and the velocity triangle parameters at different blade heights, referring to the engineering manual and data from the same type of turbine, the Pritchard11 parameterized modeling method is used to shape the blade cascade. The three-dimensional shape of the blade cascade is formed using the center of gravity stacking law, and the three-dimensional geometric files of the two-stage turbine are obtained.Numerical calculations and flow field analysis were conducted using NUMECA, and the influence of the airflow angle on the output power ratio of the turbine was given. The output power of the two-stage turbine was adjusted as a prototype for the design. Considering the shortcomings in parameterized blade design, the impact of blade cascade design on the performance and flow of two-stage turbines was analyzed, mainly focusing on the effects of unguided angle, leading edge shape, and blade bend.The counter rotating turbine designed in this article has a flow rate of 4.91kg/s and an efficiency of 88.14%.
