Feedforward-feedback compound control method and application for flow field in 2 meter high-speed free jet wind tunnel

2 m高速自由射流风洞流场前馈-反馈复合控制方法研究与应用

China Aerodynamics Research and Development Center, Mianyang 621000, China

Received: 13 May 2024

Abstract

The 2 meter high-speed free jet wind tunnel is the first large-scale open jet wind tunnel with Mach number covering sub-span and super-span flow in China. There are two difficulties in the flow field control of the wind tunnel: Firstly, the wind tunnel flow field itself has the characteristics of large hysteresis and strong nonlinearity, which increases the difficulty of flow field control; Secondly, the flow field will be strongly and continuously disturbed during the wind tunnel operation, which requires the control system to have fast anti-interference ability. To solve the above problems, a feedforward-feedback compound control method of flow field is proposed in this paper. The feedforward control is based on the principle of flow conservation, which establishes the function relation of total pressure, air source pressure, Mach number and pressure regulating valve opening, so as to obtain the feedforward control law to quickly suppress the external interference of flow field, and the feedback control is based on variable gain PI control to further improve the steady-state control accuracy of flow field. By adopting the compound control strategy, the problem of high-precision control of wind tunnel flow field in the presence of various external disturbances has been successfully solved, and the unique flow field control requirements such as supersonic continuous variable Mach number in the wind tunnel have been realized.

摘要

2 m高速自由射流风洞是我国首座马赫数涵盖亚跨超的大型开口式射流风洞。该风洞在流场控制上存在2个难点: ①风洞流场本身具有大滞后性和强非线性特点, 增大了流场控制难度; ②风洞运行过程中流场会受到强烈的、持续性的干扰, 要求控制系统具有快速的抗干扰能力。针对上述问题, 基于流量守恒原理建立了调压阀开度关于气源压力、总压、马赫数的多变量阀门特性函数, 在此基础上形成前馈控制率, 结合变增益比例积分(proportional integral, PI)控制, 构成了流场前馈-反馈复合控制策略, 成功解决了在多种外部干扰存在的情况下风洞流场高精度控制难题, 同时实现了该风洞超声速连续变马赫数等独特的流场控制需求。