Spectral analysis of self-sustained oscillations for the free jet under variable outlet conditions

22nd Fluid Mechanics Conference

物理学;力学

Pawlowska, A.^1 ; Drobniak, S.^1 ; Domagala, P.^1

Czstochowa University of Technology, Faculty of Mechanical Engineering and Computer Science, Institute of Thermal Machinery, Al. Armii Krajowej 21, Czstochowa

42-200, Poland^1

关键词: Axisymmetric jet;    Experimental verification;    Free jets;    Hot wire measurements;    Nozzle exits;    Self-sustained oscillations;    Shear layer;    Turbulence intensity;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/760/1/012021/pdf
DOI  :  10.1088/1742-6596/760/1/012021

学科分类：力学，机械学

来源: IOP

【 摘 要 】

The paper presents results of research devoted to the experimental verification of the new regime of self-sustained oscillations in the free axisymmetric jet, which was found numerically at the Institute of Thermal Machinery. Self-sustained oscillations may only appear when two conditions are fulfilled: the exit shear layer should be sufficiently thin and the level of turbulence intensity at the nozzle exit should be sufficiently low. The hot-wire measurements were performed for wide range of exit shear layer thicknesses and level of initial turbulence intensity, which allowed to formulate the preliminary conclusions regarding the conditions required for the appearance of the new phenomenon and its scaling as well as to verify the results of numerical modelling.