Laser Turbulence Measurements in the LB/TS

Turbulence of gas flows by its very nature is one of the most difficult things to model and measure. We propose to develop a new way of measuring the turbulence and to compare these measurements to predictions using the k-epsilon model. Typical measurements, in the past, use smoke, Schlierin or shadow graph techniques to visually infer turbulence characteristics. These features are either motion patterns or an average density across a slice of the turbulent flow. The technique that we propose to develop uses a laser that pulses at rates of up to 8 kHz with 30 ns pulse widths. These laser pulses would then be utilized to illuminate seeds in the flow and provide the method of framing pictures on a streak camera film. These pictures could then be employed to track the displacement-time history of the seed. the sequence of photographs would provide velocity-time histories at given points in the turbulent flow that could then be compared to the computer model. Military uses: distribution of chemical and biological agents from structures. Civilian Uses: Aircraft noise, aerodynamics and the distribution of pollutants from smoke stacks.