AN APPLICATION OF A LOW COST HIGH CONTRAST OIL FLOW VISUALIZATION TECHNIQUE IN A TRANSONIC BLOW-DOWN WIND TUNNEL FOR THE INVESTIGATION OF SECONDARY FLOWS

摘要

This paper presents an application of an oil flow visualization technique on a transonic linear turbine cascade in a blow-down wind tunnel facility. The technique employs ultraviolet (UV) sensitive dye, low cost off the shelf components, and simple image post processing to yield high quality high contrast results. Previous UV sensitive oil flow visualization techniques used high cost UV light sources, high cost cameras, and were usually carried out in continuous flow low-speed wind tunnels. This paper presents a low cost alternative and addresses the challenges that arise in applying oil flow visualization in a blow-down transonic wind tunnel. The flow visualization was applied to a linear transonic turbine cascade at the design incidence and the outlet design Mach number of 0.8 with a Reynolds number based on outlet velocity of about 600,000. Additionally, to investigate the effects of the transient nature of a blow-down facility on the flow visualization results, real time video was recorded during testing (wind-on).