Parametric study of a frequency-modulated pulse jet by measurements of flow characteristics

Abstract

Recently, pulsed jet actuators have been discovered as an efficient and promising technique for flow separation control. In this paper, a systematic experimental investigation is carried out using a flow control approach, in order to study the flow field characteristics of a baseline single pulsed jet actuator, under different excitation conditions. The findings are used to provide a better understanding of pulsed blowing actuator operation and the associated flow physics. In these experiments, two types of signal waveforms have been implemented to produce the pulsed excitation of jet; a simple squarewave excitation signal for the first case and a burst modulated excitation signal for the second case. All measurements were conducted using a single hot-wire system to an axial distance x/D30 along the centerline. The effects of electrical parameters on properties of a single pulsed jet, including the excitation frequency from 10 up to 220 Hz and the duty cycle from 15% up to 80% for the first case, and different combinations of the carrier frequency and the modulating frequency for the second case have been studied. These measurements revealed a significant dependence of mean centerline velocity and turbulence intensity to excitation signal, frequency, and duty cycle. The statistical flow properties, such as mean centerline velocity decay and turbulence intensity distribution of pulsed jets are quantified and compared together over a wide range of pulsing parameters. This investigation aids in designing and optimizing flow control actuators in aerodynamics and combustion chambers. NomenclatureRECEIVED

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