This study investigated the thermal-hydraulic characteristic of a circular tube equipped with self-rotating twisted tapes (SRTTs) at different length ratios (LR = 0.3, 0.45, 0.6, and 1) when the Reynolds number is in the range of 12,000 to 45,000. The experimental outcomes revealed that full-length SRTTs can start rotating at a lower Reynolds number (Re = 18,700), and larger length ratios significantly increase the rotational speed. Moreover, the tube equipped with full-length SRTTs was found to provide a higher friction factor, thermal performance factor and Nussle number compared with those with shorter length ratios. The thermal performance factor was considerably increased from 0.91 to 0.95, 0.95 to 1.05, 1.04 to 1.08, and 1.09 to 1.27 owing to the operating condition of SRTTs switching from a stationary to a rotating condition. Finally, this study also derived associated correlations regarding the length ratio to predict the thermal performance in formulas of the Nussle number and friction factor.

这项研究调查了当雷诺数在12,000至45,000范围内时，装有不同长度比（LR = 0.3、0.45、0.6和1）的自旋转扭曲带（SRTT）的圆管的热工液压特性。 。实验结果表明，全长SRTT可以以较低的雷诺数开始旋转（Re = 18,700），并且更大的长度比会显着提高转速。此外，发现与全长比短的管相比，配备全长SRTT的管具有更高的摩擦系数，热性能系数和Nussle数。由于SRTT从静止状态转换为旋转状态的工作条件，热性能因数从0.91提高至0.95、0.95提高至1.05、1.04至1.08和1.09至1.27。最后，这项研究还得出了与长径比有关的相关性，以Nussle数和摩擦系数的公式预测热性能。