Development of a Low Cost Cascade Aerodynamics Test Facility Using a Simple Flow Visualization Velocimetry Technique

A unique cascade test facility has been developed for use in the Wichita State University (WSU) water table. Although small in scale, the WSU water table has the advantage of low cost and the ease with which test conditions can be varied. Water table facilities have been used in the past for cascade experiments, especially as analogies for compressible flow visualization of turbine cascades. However, the lack of a quantitative measurement technique at low speeds has precluded the use of the water table as an analogy for testing subsonic compressors and turbines. In the present experiment, the hydrogen bubble flow visualization technique is used to generate bubble time lines, and a CCD (Charge Coupled Device) video camera system captures and digitizes these time line images. A VisualBASIC^® computer program is then used to determine the wake velocity profile based on the difference in bubble line positions at successive intervals of time. Preliminary results from this flow visualization velocimetry technique applied to the water table facility are presented.