Effect of compressibility in modeling of a Zero-Net-Mass-Flux actuator - An experimental and computational study

An experimental and computational study on a small 3-ounce Zero-Net-Mass-Flux (ZNMF) electrodynamic actuator has been conducted to evaluate its performance for an applied voltage and frequency. The actuator was enclosed in a casing through which a nominally two-dimensional oscillatory jet of a desired width is ensued. The jet exit velocity was measured with a three-component hot-wire anemometer. The experimental data was obtained for four slit openings of 0.0075in, 0.010in, 0.015in and 0.020in. Numerical simulations for the experimental cases were performed using the CFD software FLUENT. It was found that for slit openings (jet exit width) greater than 0.010in, the computations assuming the flow inside the actuator cavity as incompressible are in excellent agreement with the experimental data. However, for slit openings less than 0.010in, the compressibility effects must be taken into account in the numerical simulations for them to match with the experimental data; the incompressible flow model is inadequate under these conditions.