Modeling and Simulation of Propeller Propulsion Model Using Wind Tunnel

Abstract

Accurate investigation of UAV propulsion model plays a very important role in developing a high fidelity complete nonlinear simulation model for UAVs. The present paper focuses on the investigation of an accurate propulsion model used in small propeller-driven UAV. First, both propeller static and dynamic characteristics are measured. Then, the engine model is identified based on experimental measurements of the engine input and output signals. Finally, the complete propulsion model is developed. Using a low speed wind tunnel, a test rig is designed and built to measure static and dynamic performance characteristics of the propeller used in the UAV. Also, it is used to measure engine input and output signals. A sting balance measures the thrust and torque. A magnetic rpm sensor measures propeller rpm and the flight data recorder measures engine throttle position. The test results are then used to find thrust, torque and power coefficients in addition to propeller efficiency. During the tests, dynamic characteristics are obtained by changing either throttle position or wind tunnel airspeed while keeping the other one constant. Both ways are used to allow covering the whole range of advance ratio until reaching the braking and windmill modes. The static characteristics are obtained over a large range of propeller rotational speeds (rpm). The results show good agreement with published data. Engine and servomotor dynamic model is then identified and the complete propulsion model is developed and validated with a very good agreement between simulation and measured data. In order to test and validate the resultant propulsion model, it is integrated into a complete six-DoF UAV simulation model. The simulation results are compared with flight test results for the UAV. This check insists on the quality of the developed propulsion simulation model.