Enhancing the Supersonic Wind Tunnel Performance Based on Plenum Temperature Control

The application of fuzzy logic controllers (FLCs) to the control of nonlinear processes, typically controlled by a human operator, is a topic of much study. In this paper, the design and application of a FLC is discussed to control the plenum chamber temperature for a blowdown supersonic wind tunnel (BSWT) with the aim of achieving the accurate and desired results. In this regard, first, a nonlinear mathematical model of special BSWT is developed in Matlab/Simulink software environment. Next, an artificially intelligent controller is designed using fuzzy logic approach. For this purpose, a proportional-derivative FLC (PD-FLC) system is developed in the Simulink toolbox to control the plenum stagnation temperature using a heater upstream of the plenum chamber. Finally, the system simulation results inside of the temperature and pressure controllers in comparison with the experimental run are presented. The results for Mach 2.5 blowdown run show the great performance of the Wind Tunnel Simulator Model and its temperature controller system. 1. Introduction Blowdown supersonic wind tunnels (BSWTs) deliver flow at constant stagnation temperature and pressure. The stagnation temperature is generally regarded to be equal to the plenum temperature which is controlled by heater upstream of the plenum chamber. During a blowdown run, the storage tank temperature and pressure that supplies plenum chamber flow decrease continuously. Thus, to maintain a constant plenum pressure as close as possible to a setpoint pressure signal, the regulator or control valve must open progressively. Besides, to maintain a constant stagnation temperature in the plenum chamber, a heater must operate continuously during a supersonic run [1–3]. The controller must operate at different stagnation pressures and Mach numbers and has to be robust to accommodate the varying pressure and mass flow requirements safely. New concepts for control are under implementation with the goal of reducing transition phase and overall loads on the models [4, 5]. The block diagram of the control systems in the proposed BSWT is illustrated in Figure 1. Figure 1: Schematic diagram of the pressure and temperature control systems in the supersonic wind tunnel. Fuzzy logic has been the area of heated debate and much controversy during the last decades. The first paper in fuzzy set theory, which is now considered to be the seminar paper of the subject, was written by Zadeh et al. [6], who is considered the founding father of the field. In that work, Zadeh was implicitly advancing the concept of approximate human