Collected Data for Oscillatory Pitch Tests on a NACA 23012 Aerofoil. Volume 1: Description and Pressure Data for a Reynolds Number 1.0 Million. G.U. Aero Report 8600

Summary: The collected data for a series of oscillatory pitch tests on a NACA 23012 aerofoil at low Mach number are presented. These tests have been conducted to establish the validity of a recently constructed wind tunnel based unsteady aerofoil test facility, and to provide a comprehensive aerodynamic data base for further aerofoil investigations. The aerofoil was oscillated in pitch about the quarter-chord axis for a variety of mean angles of incidence, amplitudes and reduced frequencies. The aerofoil aerodynamic characteristics were evaluated from the simultaneous measurement of the outputs from miniature pressure transducers distributed in a chordwise manner at the mid-span. These pressures were logged by a dedicated micro-computer based data acquisition system and recorded in real-time on a disc volume for subsequent analysis. Static stall of the NACA 23012 aerofoil was found to occur by the mechanism of abrupt trailing-edge separation, which became more abrupt with Increasing Reynolds number. The qualitative features observed during dynamic stall were found to be similar to those documented previously by other Investigators, Including the formation of a vortex disturbance shed from the aerofoil leading-edge region. Two features were noted that appeared to be prevalent at the low Mach numbers of the current tests. These were a pronounced non-linear lift overshoot during dynamic stall and the presence of strong secondary vortex shedding. The collected data are presented in two volumes. Volume 1 contains the test data at a Reynolds number of one million and Volume 2 contains data for a Reynolds number of 1.5 million