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UNSTEADY CHARACTERISTICS OF TIP-LEAKAGE FLOW IN AN AXIAL FLOW FAN

Keuntae Park
Department of Mechanical & Aerospace Engineering Seoul National University 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Korea

Haecheon Choi
Department of Mechanical & Aerospace Engineering Seoul National University 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Korea

Seokho Choi
Air Conditioning R&D Lab. LG Electronics 51 Gasan digital 1-ro, Geumcheon-gu, Seoul, 08592, Korea

Yongcheol Sa
Air Conditioning R&D Lab. LG Electronics 51 Gasan digital 1-ro, Geumcheon-gu, Seoul, 08592, Korea

Oh-kyoung Kwon
National Institute of Supercomputing and Networking Korea Institute of Science and Technology Information 245 Daehak-ro, Yuseong-gu, Daejeon, 34141, Korea

Abstract

An axial flow fan with a shroud generates complicated tipleakage flow by the interaction of the axial flow with the fan blades and shroud near the blade tips. In this study, large eddy simulation (LES) is performed for tip-leakage flow in a forwardswept axial flow fan inside an outdoor unit of an air-conditioner, operating at the design condition of the Reynolds number of 547,000 based on the radius of blade tip and the tip velocity. A dynamic global model (Lee et al., 2010) is used for a subgridscale model, and an immersed boundary method in a non-inertial reference frame (Kim and Choi, 2006) is adopted. The present simulation reveals the evolution of tip-leakage vortex (TLV) near the blade tip. After inception of TLV near the leading edge of the suction-side of the blade tip, it develops downstream, and migrates toward the pressure surface of the following blade. Along the trajectory of the TLV, the turbulent kinetic energy and pressure fluctuations are high due to the oscillatory feature of the TLV. Energy spectra of the velocity fluctuations near the following blade and the trajectory of the TLV indicate that the TLV shows low-frequency wandering movement.