本研究利用一小型風洞及聲源產生器系統，實驗探討管流中軸向紊流強度對熱傳之影響。一聲源產生器附著在風洞的開口端，用以於管道內產生一可控制振幅之軸向聲波場，因此，造成可控制大小之軸向的速度擾動。藉由適當的選擇聲波頻率，可在風洞測試區產生幾近相等之軸向速度擾動。研究內容包括利用熱電偶(Thermocouple)作靠近測試壁面之溫度量測，以獲得熱對流係數及溫度邊界層分布；同時，利用雷射測速儀系統作靠近測試壁之速度量測以了解速度邊界層分布。此研究結果顯示軸向速度擾動並未對熱傳具有增益之效應。
This research applied a wind tunnel system and a loudspeaker system toinvestigate the only axial turbulence intensity effect on heattransfer enhancement in duct flows. The loudspeaker was attached tothe exit plane of wind tunnel to generate an acoustic wave inside thewind tunnel system. Nearly constant axial velocity perturbations inthe test section of wind tunnel were obtained by carefully adjustingthe frequency of the generated acoustic wave. The study included thetemperature measurements by thermocouples along a heated wall toobtain the Nusselt numbers and thermal boundary layers under differentaxial turbulence intensities. Also, the near-wall velocity fields weremeasured by an LDV system to check the applicability of the developedsystem and to characterize velocity boundary layer. The resultssuggest that the axial turbulence intensity plays a negligible role inheat transfer enhancement. This research applied a wind tunnel system and a loudspeaker system toinvestigate the only axial turbulence intensity effect on heattransfer enhancement in duct flows. The loudspeaker was attached tothe exit plane of wind tunnel to generate an acoustic wave inside thewind tunnel system. Nearly constant axial velocity perturbations inthe test section of wind tunnel were obtained by carefully adjustingthe frequency of the generated acoustic wave. The study included thetemperature measurements by thermocouples along a heated wall toobtain the Nusselt numbers and thermal boundary layers under differentaxial turbulence intensities. Also, the near-wall velocity fields weremeasured by an LDV system to check the applicability of the developedsystem and to characterize velocity boundary layer. The resultssuggest that the axial turbulence intensity plays a negligible role inheat transfer enhancement.
