Optical Techniques for Flow Visualization and Flow Field Measurements in Aircraft Turbomachinery.

摘要

In the program two new optical methods of flow measurement were evaluated for eventual use in aircraft turbine engines. The methods studied were: holographic interferometry for visualization of flow and laser doppler velocimetry (LDV) for pointwise measurement of velocity. Prototype instruments of each type were built and tested in measurements on a supersonic cascade. It was found that double-pulse diffuse-background holographic interferometry can disclose the position of moving density gradients such as blade shocks. The LDV system, a dual beam,dual scatter system capable of both forward and back scatter operation,was found to be effective in measuring mean velocity and turbulence intensity. Capabilities and limitations of both instruments were assessed and requirements for internal measurements in turbomachinery determined. In general,it was concluded that the equipment developed is ready for application in turbine engines. (Author)