A Correction method based on probability density function and measurement volume for turbulence intensity profile measured by LDV in turbulent pipe flow

円管乱流におけるLDVで計測された乱流強度分布に対する確率密度関数と測定体積に基づく補正法

和田 裕貴   ; 古市 紀之*; 草野 英祐*; 辻 義之*

Wada, Yuki; Furuichi, Noriyuki*; Kusano, Eisuke*; Tsuji, Yoshiyuki*

壁乱流における壁面近傍のLDV計測では相対的に測定体積が増大することにより乱流強度が過大評価されることが知られている。本発表では過大評価された測定値から真の乱流強度分布を推定する方法を提案する。円管乱流実験においてLDVでの測定位置を調整することにより相対的な測定体積を変化させて計測した乱流強度分布を用いて本補正法の妥当性について検証する。

Spatial resolution effect of LDV (Laser Doppler Velocimetry) on the time-averaged statistics is presented in high Reynolds number turbulent pipe flow. Employing PDF (Probability Density Function) of streamwise velocity, we report the study of overestimation of time-averaged statistics based on the size of measurement volume. We proposed a simple equation to estimate their spatial resolution effect. Using the proposed equation, the measurement position and the measurement volume calculated precisely based on experimental setup, it was found that the correction for spatial resolution effect is possible. Analyzing the pipe flow data measured by LDV, we estimated the expected turbulence intensity profile. The validity of the present correction method was confirmed by comparing the correction result based on the low-resolution experimental result with the high-resolution experimental result.