Simultaneous measurement of velocity-gradient and fluctuating static pressure in a turbulent planar jet

Abstract

Simultaneous measurement of the velocity-gradient and fluctuating static pressure was carried out in a turbulent planar jet. We use a constant-temperature hot-wire anemometry and a miniature pressure probe for velocity measurement and fluctuating static pressure measurement, respectively. Two types of the combined probe are introduced for simultaneous measurement of the velocity-gradient and fluctuating static pressure. One consists of an X-type hot-wire probe and a pressure probe and the other consists of two I-type hot-wire probes arranged in vertical direction and a pressure probe. For improvement of the measurement accuracy, the responsivity of the pressure probe, the time-lag due to the spatial distance between the hot-wire probe and the pressure probe, and the attenuation of the velocity-gradient measurement due to the finite difference method, are corrected. In this paper, we compare the various statistics of the turbulent planar jet acquired using the combined probes and those acquired using hot-wire probe or pressure probe alone. Through the results, it is confirmed that the simultaneous measurements were well-performed in the turbulent planar jet expect for the outside of the velocity half-width. Further, it is revealed that the Pressure Rate-of-Strain Correlation, which appears in the Reynolds stress transport equation, is almost dominated by (p´/ρ)(∂u´2/∂x1) and (p´/ρ)(∂u´1/∂x2) barely contributes to the Reynolds stress transport in the cases of Re ≥ 10,000.

Keywords

• turbulent jet
• simultaneous measurement
• static pressure measurement
• velocity-gradient