下向き閉塞分岐配管に生じる流動と温度変動のメカニズム : 第3報,水平部を有する曲がり管に生じる壁面の温度変動(流体工学,流体機械)

Abstract

Hot water in main pipe flows into the branch pipe and form thermally stratified layer with cold water at the bent section. Velocity fluctuation of the downward vortex may cause swaying of the layer. To investigate its impact on pipe wall temperature fluctuation, wall temperature distributions at the bent section were obtained experimentally for various main flow velocities. These experiments revealed that, (1) wall temperature fluctuation was attenuated significantly by heat transfer but it was also observed above and below the thermally stratified layer due to heat conductance through the wall; (2) the area of significant wall temperature fluctuation distributed horizontally for main flow velocity of 6 and 7m/s and it distributed in a block at extrados of the bent section for main flow velocity of 10-13m/s; (3) the maximum wall temperature fluctuation was 0.25 of main to branch fluid temperature difference; (4) the major peak of wall temperature fluctuation was observed within the range of 0.0015-0.0068Hz for main flow velocity of 6, 11 and 13m/s.