二維網格紊流之實驗分析

An Experimental Study on Two-Dimensional Grid Turbulence

溫志湧(Chie-Yung Wen) ； 郭威伸(Wei-Shen Kuo)

《科學與工程技術期刊》 2卷3期 (2006/09) Pp. 85-93

https://doi.org/10.7117/JSET.200609.0085

摘要

本研究是利用一種可產生理想二維流的垂直連續式肥皂膜水洞進行二維網格紊流實驗的探討，實驗中以雷射都普勒測速儀(LDV)作定量分析，並以流場可視化作定性觀察。經由雷射都普勒測速儀量測在不同肥皂膜寬度、不同位置與不同流速下二維網格紊流之速度微擾功率頻譜(power spectrum)，藉以研究渦流結合與可壓縮性對於二維網格紊流中的雙向分支(double-cascade)理論的影響。實驗結果發現二維網格紊流中之分支區段分佈似乎與可壓縮性無關，而影響其分支區段的因素中以不同量測點位置的影響為甚，二維網格紊流中的分支區段分佈具有間歇性(intermittency)之現象。

關鍵字

肥皂膜水洞 ； 二維網格紊流 ； 雙向分支理論

並列摘要

A new experimental approach for studying the double-cascade theory in two-dimensional (2D) turbulence is presented. A vertical soap-film tunnel and a comb were used to generate the 2D grid turbulence. Flow visualization and measurement of the velocity fluctuations were emphasized in the experiments. A traditional camera was used to visualize the wake behind the grid, with an interest in finding the evolution of the wake vortices and the interactions between nearby vortices. A laser Doppler velocimeter (LDV) was used to measure the velocity fluctuations in the turbulent flow field. The power spectra of the fluctuations were analyzed and compared with the double-cascade theory. The effects of compressibility on 2D turbulence were also investigated by a series of experiments. No effect on the double-cascade spectra was found. The 2D grid turbulence indicated an intermittent double-cascade phenomenon sensitive to the measuring location.

並列關鍵字

soap film tunnel ； two-dimensional grid turbulence ； double cascade theory