정현파 형상 평면 노즐 제트의 유동특성에 관한 실험적 연구

Abstract

Flow characteristics of a turbulent plane jet issuing from a sinusoidal nozzle exit configuration was investigated using a hot-wire anemometry and PIV velocity field measurements. The upper and lower nozzle plates of sinusoidal shape were arranged to have in-phase and 180o out-of-phase configurations. A hot-wire anemometry was employed to measure the vertical velocity profiles and PIV measurements were conducted to measure whole velocity field information of the jet flow in several horizontal planes. Mean velocity and turbulence intensity profiles in vertical planes at three lateral spanwise locations(0, λ/4 and λ/2) were measured at several downstream locations(x/D= 0.5~6). The jet velocity at the nozzle exit was 3 m/s and corresponding Reynolds number based on the mean width of the nozzle was ReD= 5000. For the case of in-phase nozzle, the length of potential core exhibit negligible difference at three spanwise locations. On the other hand, the 180o out-of-phase nozzle configuration shows large difference of 30% in the length of potential core along the spanwise direction. The turbulence intensity also shows significantly different spatial distribution for the out-of-phase nozzle configuration. Flow visualization results reveal the presence of non-symmetric vortical structure, yielding the large different vortex structure for the two nozzle configurations. The jet flow issuing from the in-phase nozzle propagates from the nozzle edge to the jet center region and shows an interesting vortical structure.