PIV measurements of a complex turbulent flow in a short elbow piping under a high Reynolds number condition

高レイノルズ数条件下におけるショートエルボ配管内複雑乱流のPIV計測

高村 宏行*; 今野 宏章*; 江原 真司*; 橋爪 秀利*; 相澤 康介 ; 山野 秀将   

Takamura, Hiroyuki*; Konno, Hiroaki*; Ebara, Shinji*; Hashizume, Hidetoshi*; Aizawa, Kosuke; Yamano, Hidemasa

In this study, flow experiments are carried by using a 1/7-scale model of a cold-leg piping by means of Particle Image Velocimetry (PIV) to elucidate the flow structure in the piping. A single elbow, a dual elbow, and a triple elbow layout are used to understand the complex flow field. Cross sections perpendicular to the mean flow direction and cross sections parallel to that contain a curvature radius of the elbow are visualized minutely by the PIV measurement. We apply spectral analysis to the velocity data in time series by means of Fast Fourier Transform (FFT). We calculate the turbulent kinetic energy and the root-mean-square (rms) of the velocity fluctuations to value the turbulent intensity. As a result of the experiments of the flow cross sections, it is elucidated how the separated flow region changes depending on Reynolds number and fluctuation frequency characteristics in flow velocity in the vicinity of the separated flow region.