Flow deflection characteristics of two-dimensional synthetic jets generated from asymmetric stepped slots

Abstract

This study examines the behavior of two-dimensional synthetic jets generated from asymmetric stepped slots, focusing on the formation of recirculation regions and jet deflection near the slot. The effects of step length and frequency on the behavior of the jets were investigated. Experiments were conducted at a constant Reynolds number (Re = 1000), with varying frequencies. A speaker was used to generate the synthetic jet. Particle image velocimetry (PIV), which employed images captured via the smoke-wire method, was used to analyze flow patterns. To evaluate jet deflection, velocity distributions were measured using a hot-wire anemometer in selected cases. This study discusses the onset conditions of the recirculation region and the deflection mechanism, examining their relationship with jet deflection, dimensionless frequency, and dimensionless step length. The key findings indicate that jet deflection, associated with the recirculation region size, is influenced by both the dimensionless step length and frequency. The jet exhibits a straight flow when the dimensionless step length is either extremely small or large. Moreover, to minimize the size of the recirculation region, larger dimensionless step lengths require smaller dimensionless frequencies. Additionally, the study establishes a flow similarity rule within the tested conditions, employing the stroke length of the synthetic jet as a representative length.

Keywords

• synthetic jet
• asymmetric stepped slot
• recirculation region
• jet vectoring
• vortex pair