Study on design characteristics of airfoil pressure distribution for low Mach number general aircraft

低马赫数通用飞机翼型压力分布设计特点研究

¹ School of Aeronautics, Northwestern Polytechnical University, Xi'an 710072, China
² Unmanned System Research Institute, Northwestern Polytechnical University, Xi'an 710072, China

Received: 19 May 2022

Abstract

This paper studies several problems that may exist in the aerodynamic design of low Mach number general aircraft, and discusses the design characteristics of the pressure distribution of some related airfoils while part of the characteristics is verified by a multi-point laminar airfoil design case. Firstly, several issues which exist in the aerodynamic design of low Mach number general aircraft, such as relatively large zero-lift drag coefficient, high stall performance requirements, and large variation range of Reynolds number, are discussed and analyzed. Then, to address these issues, the paper extracts some useful design features that are beneficial to the airfoil aerodynamic performance from the study on the design characteristics of the pressure distribution of several turbulent flow airfoils and laminar flow airfoils that are designed for low Mach number general aircraft. Finally, by considering the typical design conditions of a light multi-purpose single-turboprop-engine general aircraft, including the cruise, climb and stall conditions, a multi-point laminar airfoil optimization is offered by using the GAW-1 airfoil as the baseline. The optimized foil has a 9.6 improvement in the lift-to-drag ratio of the cruise condition, a 16.3 improvement in the lift-to-drag ratio of the climb condition but a 0.115 decrease in the maximum lift coefficient of the stall condition. The results show that the requirements from the cruise, climb and stall conditions are contradictory to some degree in the considering multi-point optimization case, and the designers should deal with this trade-off carefully based on the features of the low Mach number general aircraft.

摘要

对低马赫数通用飞机气动设计中可能存在的问题进行了研究和总结, 讨论分析了部分相关翼型的压力分布形态的设计特点, 并通过多工况层流翼型设计实例验证了部分翼型设计理念。对低马赫数通用飞机气动设计存在零升阻力较大、失速性能要求较高、雷诺数变化范围较大等问题进行了讨论分析。为了解决这些问题, 对若干低马赫数通用飞机的湍流翼型和层流翼型的压力分布形态进行了研究, 提取部分对翼型气动性能有利的设计特点。以GAW-1翼型为基准, 提取某型单发涡桨式轻型多用途通用飞机的典型设计工况, 进行了考虑巡航、爬升和失速的多工况层流翼型优化设计。设计结果巡航升阻比提升了9.6, 爬升升阻比提升了16.3, 但失速最大升力系数减小了0.115。研究结果表明: 考虑巡航、爬升和失速的多工况层流翼型设计需求较为矛盾, 设计人员应基于低马赫数通用飞机构型特点仔细权衡和取舍。