Experimental study of turbulent flow and heat transfer behaviors over a micro-rib-dimple-structured surface

2021 ◽  
pp. 1-27
Author(s):  
Kuan Zheng ◽  
Wei Tian ◽  
Peng Zhang ◽  
Yu Rao ◽  
Hui Hu
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Flow Field ◽  
Thermal Efficiency ◽  
Turbulent Mixing ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Structured Surface ◽  
Recirculating Flow ◽  
Rib Structure

Abstract An experimental study was conducted to characterize the evolution of turbulent boundary layer flow over a micro-rib-dimple-structured surface. In addition to measuring the surface pressure distribution and detailed flow field inside the dimple cavity, the heat transfer performance over the rib-dimpled surface was investigated using transient liquid crystal thermography. The flow field measurements were correlated with the heat transfer measurements to elucidate the underlying physical mechanism of the improvement in thermal efficiency due to the micro-rib structure. It was found that, compared to the dimpled surface, the micro-rib structure induces a stronger downwash flow and acts as a tabulator to enhance the turbulent mixing of the downstream flow, which significantly restricts the flow separation and the recirculating flow inside the dimple cavity. The dominant flows inside the dimple cavity are the downwash and successive upwash flows, which significantly enhance the turbulent mixing and consequently, improve the heat transfer performance over the rib-dimpled surface. The measurements of the pressure loss and heat transfer performance indicated that the rib-dimpled surface has an overall thermal efficiency approximately 12%−16% higher than that of the dimpled surface owing to the micro-rib structure.

Effects of the novel rib layouts on the tip leakage flow pattern and heat transfer performance of turbine blade

2020 ◽  
Vol 234 (8) ◽  
pp. 1446-1459
Author(s):  
Shijie Jiang ◽  
Zhigang Li ◽  
Jun Li ◽  
Liming Song
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Turbine Blade ◽  
Heat Transfer Performance ◽  
Pressure Coefficient ◽  
Tip Clearance ◽  
Prototype Model ◽  
Transfer Performance ◽  
Tip Leakage Flow ◽  
Rib Structure

The steady simulation with flow field and heat transfer performance for different rib layouts is investigated. By referring the GE-E3 turbine blade tip (Case 1) profile as a prototype model, four kinds of rib layouts of full rib structure (Case 2), half rib structure connected with suction side (Case 3), half rib structure connected with pressure side (Case 4), and half rib structure in the rear squealer cavity (Case 5) was designed. The availability of k-ω turbulence model was validated through comparison of heat transfer coefficient distribution with the experimental data. The area-averaged heat transfer coefficients of Case 5 decreases up to 11.3%, 3.1%, 11.3%, and 2.8% in comparison to Cases 1, 2, 3, and 4. The total pressure coefficient of Case 5 reduces by 1.4%, 2.7%, and 4.0% compared to Cases 1, 2, and 3. The results reveal that, among the five novel rib layout cases, Case 5 obtains the optimal comprehensive performance under the performance of considering tip heat transfer and cascade loss. Further investigation on the influence of Cases 1 and 5 at different rotational speeds on the flow field and heat transfer characteristics of the tip clearance is also illustrated and discussed.

Experimental Study on Heat Pipe Radiator in Cooling Electronic Apparatus

2012 ◽  
Vol 197 ◽  
pp. 216-220
Author(s):  
Zhong Chao Zhao ◽  
Rui Ye ◽  
Gen Ming Zhou
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Pipe ◽  
Heat Dissipation ◽  
Heat Transfer Performance ◽  
Electronic Device ◽  
Transfer Performance ◽  
Air Velocity ◽  
Electronic Apparatus ◽  
Operational Temperature

To solve the cooling problem in modern electronic device, a kind of heat pipe radiator was designed and manufactured in this paper. The heat transfer performance of heat pipe radiator and its relationship with air velocity were investigated by experimental method. The experimental results show that the heat pipe radiator can meet the temperature requirement of electronic device with the power range from 40W to 160W. To keep the operational temperature of electronic device with power of 160W under 75°C，the air velocity should be keep at 1.7m/s. The heat dissipation performance of heat pipe radiator was enhanced with the air velocity increased from 0.2m/s to 1.7m/s.for the electronic equipment with power of 160W.

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