DUAL HOLOGRAM SHEARING INTERFERENCE TECHNIQUE WITH ENHANCED SENSITIVITY FOR WIND-TUNNEL TESTING

A novel optical diagnostic approach, namely, a dual hologram shearing interferometry with enhanced sensitivity, is proposed for visualizatio n, and for measuring the density gradients of the flow in wind tunnels . The technique is especially useful for strong turbulent and/or unste ady regions flows. The features of the technique make it tolerant to v ibrational disturbances typical to many wind tunnel facilities. The me thod was demonstrated by its application to a supersonic flow over a s pherically blunted nose cone/cylinder model.