Nauka i Obrazovanie (Jan 2015)

Investigation of Synthetic Jets Efficiency to Control Cavity Flotation with Subsonic External Flow by High-Resolution RANS / ILES Method

  • D. A. Lyubimov,
  • A. E. Fedorenko

DOI
https://doi.org/10.7463/0315.0761617
Journal volume & issue
Vol. 0, no. 3
pp. 49 – 67

Abstract

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Cavities often found in airplanes: a niche for the landing gear, various weapons, etc. Reducing fluctuations of pressure and temperature in the cavity is a relevant practical problem. The article presents simulation results of external subsonic flow around the cavity (M = 0.85, T = 300K). ). Calculations were performed using the high-resolution RANS/ILES (Reynolds Averaged Navier-Stokes - RANS, Implicit Large Eddy Simulation - ILES) method. To control flow the authors propose to use synthetic jets. Synthetic jets are produced by periodic ejection and suction of fluid from a slot induced by the movement of a diaphragm (generator of synthetic jets) inside a cavity. They are compact and efficient and do not require a special working body and the ways for its supply. Instead of calculating the flow in the synthetic jet generator was used the modified boundary condition on the wall where the output slots was positioned. Under consideration there were two variants of slots for synthetic jets output: in front of the cavity and inside the cavity on the front wall. The frequency and amplitude values of the synthetic jet specified a mode of each jet. For a jet inside the cavity two modes have been reviewed, namely: 100 Hz and 50m/s, 200Hz and 50m/s. For jet in front of the cavity three modes have been reviewed, specifically: 20Hz and 20m/s, 100Hz and 50m/s, 200Hz and 50m/s. Analysis of calculation results showed that for all modes under examination, the synthetic jets reduced fluctuation of static pressure and temperature on the bottom and back walls of the cavity. The mode with parameters 200Hz, 50 m/s and synthetic jet located in front of the cavity was the most efficient. Furthermore, we compared the results of calculations for two-and three-dimensional cavities, which have the same length and depth. Research has shown that the simplified quasi-two-dimensional calculations cannot be used to evaluate the pressure and temperature fluctuations. This is due to, essentially, three-dimensional distribution of temperature and pressure fluctuations on the back wall of the cavity where they are, usually, maximal.

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