Experimental investigation on noise emissions of an airfoil with non-flat plate trailing edge serrations
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DOI 10.1007/s12206-019-0601-x
Experimental investigation on noise emissions of an airfoil with non-flat plate trailing edge serrations†4
Eryun Chen1,2,*, Yang Ma1, Ailing Yang1,3,* and Gaiping Zhao 1
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China 2 Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, Shanghai, 200093, China 3 Key Laboratory of Aerodynamic Noise Control, China Aerodynamics Research and Development Center, Mian Yang, 6213000, China 4 School of Medical Instruments and Food Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China (Manuscript Received August 12, 2018; Revised March 28, 2019; Accepted April 3, 2019) ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Abstract This paper presents an experimental study on the aeroacoustic characteristics of a NACA 0018 with nonflat plate-type serrated trailing edge at Reynolds numbers of 500000 in an open-jet wind tunnel. The experimental results show that noise reduction can be achieved in the moderate frequency range for nonflat plate type triangular serrated trailing edges, but at the cost of producing narrowband tone noise. The level of the vortex shedding noise declines when serration length 2 h decreases. It is imperative that the vortex shedding tone noise be completely suppressed when a novel slanting root serrated trailing edge is adopted. Meanwhile, the ability of broadband noise reduction is maintained. Keywords: Trailing edge serrations; Slanting root serration; Trailing edge noise ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1. Introduction Noise emitted from the trailing edge of an airfoil blade is believed to be a major noise source in many industrial applications, such as cooling fan blades, air frames or wind turbines, to name a few. The mechanism of which is attributed to the interaction between an airfoil blade and the turbulence produced in its own boundary layer [1]. When turbulent fluctuations encounter a solid body with a sharp edge, a scatter process occurs more efficiently than in free-space (Ma5 c.f. Ma8), which leads to a considerable increase in the radiated sound power [2, 3], in particular for low Mach numbers flow. It poses a serious threat to human well-being and the environment in general. Therefore, there has been much interest in developing control methods aimed at reducing trailing edge noise [4]. Trailing edge noise can be reduced in an active way or in a passive way [5]. With regard to the passive techniques, it has lo
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