Abstract
This paper aims to measure the drag acting on a racing car model designed and made by students in Miyakonojo College, National Institute of Technology (KOSEN) and to visualize flow fields around the model by means of Particle Image Velocimetry (PIV) and Computational Fluid Dynamics (CFD). Large Eddy Simulation (LES) model for CFD is adopted to simulate turbulent flows around and behind the model. Flow separation on the model top-roof and longitudinal vortices at the model sidewalls are demonstrated in detail by the PIV visualization and are confirmed by the simulation. Separation frequency obtained from the simulation is processed by the fast Fourier transformation (FFT) of the velocity, clarifying that the frequency increases according to a power law of Reynolds number. The coalescence of the separation vortices and the longitudinal ones behind the model are demonstrated by the simulation, indicating that a negative pressure region generated by the coalescence of these vortices largely affects the aerodynamics drag of the model. The drag coefficient evaluated from the measured drag is compared with that obtained from the simulation, the latter of which is expressed in the form of a power law of Reynolds number. The results obtained suggest suitable positions of plasma actuator (PA) to be installed on the model for flow control.
