Characteristics of Turbulent Flow Past Passive Rectangular Cavity at Large Reynolds Numbers
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ORIGINAL CONTRIBUTION
Characteristics of Turbulent Flow Past Passive Rectangular Cavity at Large Reynolds Numbers P. K. Ezhil Kumar1 • Debi Prasad Mishra1
Received: 19 November 2018 / Accepted: 27 May 2020 Ó The Institution of Engineers (India) 2020
Abstract In the present investigation, turbulent flow past passive rectangular cavity is investigated numerically for four mainstream Reynolds numbers, namely Rems= 20,000 to 50,000. Validation study reveals that the numerical models used in the present investigation predict the data close to the existing experimental results. Further attempts are made to bring out the flow structure in terms of velocity profile, velocity gradients, shear layer growth rate and turbulence characteristics. Numerical results are analyzed to bring out the variation in the velocity profile at different axial locations within the cavity. Also, the velocity gradient, turbulence level at the shear layer and the reverse flow velocity in the cavity are found to be sensitive to the mainstream Reynolds number. Finally, the cavity drag is estimated and its relation to the pressure drop across the combustor is brought out. These results reveal the nature of interaction between the passive cavity flow and mainstream flow. List of Dc Vi Vms Vr;max q k x SST Rems
Symbols Cavity drag Velocity, m/s Mainstream velocity, m/s Maximum reverse flow velocity, m/s Density, kg/m3 Turbulent kinetic energy, m2/s2 Specific dissipation rate Shear stress transport Mainstream Reynolds number
& Debi Prasad Mishra [email protected] 1
Department of Aerospace Engineering, Indian Institute of Technology, Kanpur 208016, India
ss h0 dx
Wall shear stress: percentage of maximum reverse flow velocity Momentum boundary layer thickness Vorticity thickness
Introduction Flow past cavities are being studied by various groups due to its application in aircraft wheel wells and bomb bays [1, 2] and open roof of automobiles. Recently, cavities are being employed as flame holders for subsonic [3] as well as supersonic combustors [4, 5]. Based on the flow structure, cavity flow can be classified as (i) open cavity flow, (ii) transition cavity flow and (iii) closed cavity flow [2, 6]. If the streamlines, separating at the cavity leading edge, reattach again at the cavity trailing edge, then the cavity flow is termed as open cavity flow [2]. On the other hand, if the separated streamline reattaches at the lateral wall of the cavity, then this type of cavity flow is termed as open cavity flow [2]. Open cavity is generally suited for flame stabilization applications as the cavity flow is literally isolated from the mainstream flow. Hence, understanding the characteristics of open passive cavity flow is very important. Yao et al. [1] have studied the laminar flow characteristics of open passive cavity flow numerically for low mainstream Reynolds number ranges. They studied the effects of cavity geometry and mainstream Reynolds number on the cavity flow structure. On the other hand, turbulent flow past open passive axisymmetric cavity i
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