Time-Resolved Temperature-Jump Measurements and Theoretical Simulations of Nanoscale Heat Transfer Using NaYF4:Yb3+:Er3+ Upconverting Nanoparticles

2019 ◽  
Vol 123 (6) ◽  
pp. 3770-3780 ◽  
Author(s):  
Ali Rafiei Miandashti ◽  
Larousse Khosravi Khorashad ◽  
Alexander O. Govorov ◽  
Martin E. Kordesch ◽  
Hugh H. Richardson
Keyword(s):  
Heat Transfer ◽  
Temperature Jump ◽  
Time Resolved ◽  
Nanoscale Heat Transfer ◽  
Theoretical Simulations

Time-resolved temperature-jump measurements and steady-state thermal imaging of nanoscale heat transfer of gold nanostructures on AlGaN:Er3+ thin films

2020 ◽  
Vol 152 (3) ◽  
pp. 034706 ◽  
Author(s):  
Kristina Shrestha ◽  
Juvinch R. Vicente ◽  
Ali Rafiei Miandashti ◽  
Jixin Chen ◽  
Hugh H. Richardson
Keyword(s):  
Heat Transfer ◽  
Thin Films ◽  
Steady State ◽  
Thermal Imaging ◽  
Temperature Jump ◽  
Gold Nanostructures ◽  
Time Resolved ◽  
Nanoscale Heat Transfer

Improved Methodologies for Time-Resolved Heat Transfer Measurements, Demonstrated on an Unshrouded Transonic Turbine Casing

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Matthew Collins ◽  
Kam Chana ◽  
Thomas Povey
Keyword(s):  
Heat Transfer ◽  
Temperature Cycling ◽  
Test Facility ◽  
Turbine Engines ◽  
Data Set ◽  
Time Resolved ◽  
High Frequency Response ◽  
High Thermal Load ◽  
Turbine Casing ◽  
Computational Fluid Dynamics Cfd

The high pressure (HP) rotor tip and over-tip casing are often life-limiting features in the turbine stages of current gas turbine engines. This is due to the high thermal load and high temperature cycling at both low and high frequencies. In the last few years, there have been numerous studies of turbine tip heat transfer. Comparatively fewer studies have considered the over-tip casing heat transfer. This is in part, no doubt, due to the more onerous test facility requirements to validate computational simulations. Because the casing potential field is dominated by the passing rotor, to perform representative over-tip measurements a rotating experiment is an essential requirement. This paper details the measurements taken on the Oxford turbine research facility (OTRF), an engine-scale rotating turbine facility which replicates engine-representative conditions of Mach number, Reynolds number, and gas-to-wall temperature ratio. High density arrays of miniature thin-film heat-flux gauges were used with a spatial resolution of 0.8 mm and temporal resolution of ∼120 kHz. The small size of the gauges, the high frequency response, and the improved processing methods allowed very detailed measurements of the heat transfer in this region. Time-resolved measurements of TAW and Nu are presented for the casing region (−30% to +125% CAX) and compared to other results in the literature. The results provide an almost unique data set for calibrating computational fluid dynamics (CFD) tools for heat transfer prediction in this highly unsteady environment dominated by the rotor over-tip flow.

Algebraic solutions of flow and heat for some nanofluids over deformable and permeable surfaces

2017 ◽  
Vol 27 (10) ◽  
pp. 2259-2267 ◽  
Author(s):  
Mustafa Turkyilmazoglu
Keyword(s):  
Heat Transfer ◽  
Design Methodology ◽  
Temperature Jump ◽  
Volume Fraction ◽  
Velocity Slip ◽  
Jump Conditions ◽  
Content Type ◽  
Layer Flow ◽  
Working Out ◽  
Algebraic Solutions

Purpose This paper aims to working out exact solutions for the boundary layer flow of some nanofluids over porous stretching/shrinking surfaces with different configurations. To serve to this aim, five types of nanoparticles together with the water as base fluid are under consideration, namely, Ag, Cu, CuO, Al2O3 and TiO2. Design/methodology/approach The physical flow is affected by the presence of velocity slip as well as temperature jump conditions. Findings The knowledge on the influences of nanoparticle volume fraction on the practically significant parameters, such as the skin friction and the rate of heat transfer, for the above considered nanofluids, is easy to gain from the extracted explicit formulas. Originality/value Particularly, formulas clearly point that the heat transfer rate is not only dependent on the thermal conductivity of the material but it also highly relies on the heat capacitance as well as the density of the nanofluid under consideration.

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