冷卻圓柱尾流特性之有效雷諾數研究

Abstract

本文針對恆溫冷卻圓柱尾流在高溫層流之實驗，研究圓柱表面溫度與自由流溫度比小於1 (T*< 1)時，溫度效應對圓柱尾流渦旋剝離之影響。自Lecordier et al.(1991) 提出有效雷諾數概念至今，已有許多加熱圓柱方面的實驗(T*> 1)，然而卻從未有加熱流場冷卻圓柱方面的實驗，圓柱尾流的熱效應經本文完成0.67<T*<1的實驗後，有效雷諾數與有效溫度在低雷諾數時完全可由實驗證實，Wang et al.(2000)之泛用史卓荷數-雷諾數曲線在實際應用上比等溫情況更有價值。另一方面也證實了有效雷諾數概念跟熱傳方向無關；冷卻圓柱使尾流不穩，與加熱圓柱可使尾流穩定之熱效應一致。

The paper deals with a non-isothermal case T*<1 of an airflow around circular cylinder in cross flow at the regime of laminar vortex shedding. Lecordier et al.(1991) originally proposed the effective Reynolds number and effective temperature concept. Wang et al. (2000) derived Teff from experiments proposed c=0.28 and St-Reeff curve for T* between 1 to 2. The thesis confirm that Wang et al.(2000) effective temperature and St-Reeff curve for T*<1. This thermal effect is consistent with known effect of flow stabilization by cylinder heating.