Interaction and acoustics of separated flows from a D-shaped bluff body
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 11 October 2021
Issue publication date: 28 March 2022
Abstract
Purpose
For flow around elongated bluff bodies, flow separations would occur over both leading and trailing edges. Interactions between these two separations can be established through acoustic perturbation. In this paper, the flow and the acoustic fields of a D-shaped bluff body (length-to-height ratio L/H = 3.64) are investigated at height-based Reynolds number Re = 23,000 by experimental and numerical methods. The purpose of this paper is to study the acoustic feedback in the interaction of these two separated flows.
Design/methodology/approach
The flow field is measured by particle image velocimetry, hotwire velocimetry and surface oil flow visualization. The acoustic field is modeled in two dimensions by direct aeroacoustic simulation, which solves the compressible Navier–Stokes equations. The simulation is validated against the experimental results.
Findings
Separations occur at both the leading and the trailing edges. The leading-edge separation point and the reattaching flow oscillate in accordance with the trailing-edge vortex shedding. Significant pressure waves are generated at the trailing edge by the vortex shedding rather than the leading-edge vortices. Pressure-based cross-correlation analysis is conducted to clarify the effect of the pressure waves on the leading-edge flow structures.
Practical implications
The understanding of interactions of separated flows over elongated bluff bodies helps to predict aerodynamic drag, structural vibration and noise in engineering applications, such as the aerodynamics of buildings, bridges and road vehicles.
Originality/value
This paper clarifies the influence of acoustic perturbations in the interaction of separated flows over a D-shaped bluff body. The contribution of the leading- and the trailing-edge vortex in generating acoustic perturbations is investigated as well.
Keywords
Acknowledgements
The first author gratefully acknowledges the support given under Joint PhD Programme between The Hong Kong Polytechnic University (PolyU) and Tongji University. The second author gratefully acknowledges the support with research studentship tenable at Department of Mechanical Engineering, PolyU. The third author gratefully acknowledges the support given by the National Natural Science Foundation of China (Grant No. 51905381), the Shanghai Key Laboratory of Aerodynamics and Thermal Environment Simulation for Ground Vehicles (Grant No. 18DZ2273300), and the Shanghai Automotive Wind Tunnel Technical Service Platform (Grant No.19DZ2290400). The fourth author gratefully acknowledges the support from a research donation from the Philip K. H. Wong Foundation (Grant No. 5-ZH1X).
Citation
Huang, G., Seid, K.H., Yang, Z. and Leung, R.C.K. (2022), "Interaction and acoustics of separated flows from a D-shaped bluff body", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 32 No. 4, pp. 1186-1203. https://doi.org/10.1108/HFF-08-2021-0543
Publisher
:Emerald Publishing Limited
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