Exploratory experimental investigation of a wave propeller

Abstract

A low-speed wind tunnel investigation was conducted to determine if a small secondary airfoil or wave propeller, oscillating in a rotary plunging motion, could significantly affect the airflow over a lifting airfoil surface to delay the onset of stall. The lifting airfoil shape was a NACA 66(215)-216, chosen for its chordwise pressure port instrumentation. Testing consisted of measuring the pressure distribution of the NACA 66(215)-216 airfoil past the stall angle of attack, and then again in combination with the wave propeller. The wave propeller was located in two different positions; above the lifting airfoil's trailing edge, and aft of the trailing edge. The propeller was operated in both clockwise and counter-clockwise directions. The propeller effectiveness was evaluated by comparing the pressure distributions and computed lift curve slopes with and without propeller operation. Reynolds number varied from 1/4X10(5) to 2.57X10(5). Mechanical limitations resulting in testing to only ten percent of the desired propeller speeds. Results indicated that the wave propeller acted to block the air flow over the lifting wing causing early separation and loss of lift.