Nobuhiko Tanaka

Study on Characteristics of Velocity and Pressure Field in Two Dimensional Turbulent Jet

A fluctuating static pressure is closely related with a fluctuating velocity in turbulent flow, and it plays an important role in the energy balance and anisotropy of turbulence. Thus, the measurement of fluctuating static pressure is very effective for clarification of the organized structure of the turbulent flow. In this study, the yaw-insensitive static pressure probe with a good frequency response was developed, and the simultaneous mesurement of velocity and pressure field was carried out in two dimensional jet flow by the combined probe of I-type hot-wire and static pressure probe.

An Experimental Study on the Development of Coherent Structure in a Plane Jet (2nd Report, Spatio-temporal Velocity Structure by the Combined Analysis of KL Expnasion and Fourier Transform)

The simulaneous measurement of the velocities at two points with X-type hot wire probes has been performed in three different downstream regions of a plane jet (i.e., the potential core region, the interaction region and the self-preserving region). Mainly by the combined analysis of KL expansion and Fourier transform, the structure development of the plane jet is investigated from a viewpoint of both space and frequency. From the downstream variation of the eigenfunctions, it is found that in the early stage of the interaction region the profiles of the 1st u- and v-POD mode in the low frequency range become self-similar, but in high frequency range these continue to change until the self-preserving region. The characteristics of coherent structure can be extracted efficiently by the spatial correlation profiles reconstructed from the 1st POD mode.