The effect of a splitter plate on the flow around a finite prism |
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| Institution: | 1. Department of Civil Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai 200240, China;2. State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai 200240, China;3. Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, No. 800, Dongchuan Road, Shanghai 200240, China;4. College of Civil Engineering and Mechanics, Xiangtan University, Xiangtan 411105, China;5. Department of Aeronautics, Imperial College London, London SW7 2AZ, UK;6. Cullen College of Engineering, University of Houston, Houston, TX 77204, USA;1. Department of Mechanical Engineering, University of Manitoba, Winnipeg, MB, Canada R3T 5V6;2. Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK, Canada S7N 5A9;1. Mathematics Department, COMSATS Institute of Information Technology, Islamabad 44000, Pakistan;2. Harbin Institute of Technology, Shenzhen Graduate School, Xili Town, Shenzhen, China;1. School of Civil Engineering, Central South University, Changsha, China;2. National Engineering Laboratory for High-speed Railway Construction, Central South University, Changsha, China;3. Institute for Turbulence-Noise-Vibration Interaction and Control, Shenzhen Graduate School of Harbin Institute of Technology, Shenzhen, China |
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| Abstract: | The effect of a wake-mounted splitter plate on the flow around a surface-mounted finite-height square prism was investigated experimentally in a low-speed wind tunnel. Measurements of the mean drag force and vortex shedding frequency were made at Re=7.4×104 for square prisms of aspect ratios AR=9, 7, 5 and 3. Measurements of the mean wake velocity field were made with a seven-hole pressure probe at Re=3.7×104 for square prisms of AR=9 and 5. The relative thickness of the boundary layer on the ground plane was δ/D=1.5–1.6 (where D is the side length of the prism). The splitter plates were mounted vertically from the ground plane on the wake centreline, with a negligible gap between the leading edge of the plate and rear of the prism. The splitter plate heights were always the same as the heights of prisms, while the splitter plate lengths ranged from L/D=1 to 7. Compared to previously published results for an “infinite” square prism, a splitter plate is less effective at drag reduction, but more effective at vortex shedding suppression, when used with a finite-height square prism. Significant reduction in drag was realized only for short prisms (of AR≤5) when long splitter plates (of L/D≥5) were used. In contrast, a splitter plate of length L/D=3 was sufficient to suppress vortex shedding for all aspect ratios tested. Compared to previous results for finite-height circular cylinders, finite-height square prisms typically need longer splitter plates for vortex shedding suppression. The effect of the splitter plate on the mean wake was to narrow the wake width close to the ground plane, stretch and weaken the streamwise vortex structures, and increase the lateral entrainment of ambient fluid towards the wake centreline. The splitter plate has little effect on the mean downwash. Long splitter plates resulted in the formation of additional streamwise vortex structures in the upper part of the wake. |
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| Keywords: | Flow control Finite square prism Splitter plate Drag reduction Vortex shedding Wake |
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