Time-resolved surface heat flux measurements in the wing/body junction vortex

10.2514/3.595 ◽  
1994 ◽  
Vol 8 (4) ◽  
pp. 656-663 ◽  
Author(s):  
D. J. Lewis ◽  
R. L. Simpson ◽  
T. E. Diller
Keyword(s):  
Heat Flux ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Time Resolved ◽  
Flux Measurements

3D Heat Transfer Assessment of Full-Scale Inlet Vanes With Surface-Optimized Film Cooling: Part 1 — Experimental Results

2019 ◽  
Author(s):  
R. J. Anthony ◽  
J. P. Clark ◽  
J. Finnegan ◽  
J. J. Johnson
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
High Frequency ◽  
Film Cooling ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Full Scale ◽  
Pressure Side ◽  
Flux Measurements ◽  
Real Hardware

Abstract Full-scale annular experimental evaluation of two different high pressure turbine first stage vane cooling designs was carried out using high frequency surface heat-flux measurements in the Turbine Research Facility at the Air Force Research Laboratory. A baseline film cooling geometry was tested simultaneously with a genetically optimized vane aimed to improve efficiency and part life. Part 1 of this two-part paper describes the experimental instrumentation, test facility, and surface heat flux measurements used to evaluate both cooling schemes. Part 2 of this paper describes the result of companion conjugate heat transfer posttest predictions, and gives numerical background on the design and modelling of both film cooling geometries. Time-resolved surface heat flux data is captured at multiple airfoil span and chord locations for each cooling design. Area based assessment of surface flux data verifies the genetic optimization redistributes excessive cooling away from midspan areas to improve efficiency. Results further reveal key discrepancies between design intent and real hardware behavior. Elevated heat flux above intent in some areas led to investigation of backflow margin and unsteady hot gas ingestion at certain film holes. Analysis shows areas toward the vane inner and outer endwalls of the aft pressure side were more sensitive to reduced aft cavity backflow margin. In addition, temporal analysis shows film cooled heat flux having large high frequency fluctuations that can vary across nearly the full range of film cooling effectiveness at some locations. Velocity and acceleration of these large unsteady heat flux events moving near the endwall of the vane pressure side is reported for the first time. The temporal nature of the unsteady 3-D film cooling features are a large factor in determining average local heat flux levels. This study determined this effect to be particularly important in areas on real hardware along the HPT vane pressure side endwalls towards the trailing edge, where numerical assumptions are often challenged. Better understanding of the physics of the highly unsteady 3D film cooled flow features occurring in real hardware is necessary to accurately predict distress progression in localized areas, prevent unforeseen part failures, and enable improvements to turbine engine efficiency. The results of this two-part paper are relevant to engines in extended service today.

Instantaneous Local Heat Flux Measurements in a Small Utility Engine

2009 ◽  
Author(s):  
Terry Hendricks ◽  
Jaal Ghandhi ◽  
John Brossman
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Numerical Model ◽  
Surface Temperature ◽  
Heat Transfer Rate ◽  
Surface Heat Flux ◽  
Transfer Rate ◽  
Surface Heat ◽  
High Load ◽  
Flux Measurements

Heat flux measurements were performed in an air-cooled utility engine using a fast-response coaxial-type surface thermocouple. The surface heat flux was calculated using both analytical and numerical models. The heat flux was found to be a strong function of engine load. The peak heat flux and initial heat flux rise rate increase with engine load. The measured heat flux data were used to estimate a global heat transfer rate, and this was compared with the heat transfer rate calculated by a single-zone heat release analysis. The measured values of heat transfer were higher than the calculated values largely because of the lack of spatial averaging. The high load data showed an unexplainable negative heat flux during the expansion stroke while the gas temperature was still high. A 1D and 2D finite difference numerical model utilizing an adaptive timestep Crank-Nicholson (CN) integration routine was developed to investigate the surface temperature measurement. Applying the measured surface temperature profile to the 1D model, the resultant surface heat flux showed excellent agreement with the analytical inversion solution and captured the reversal of the energy flow back into the cylinder during the expansion stroke. The 2D numerical model was developed to observe transient lateral conduction effects within the probe and incorporated the various materials used in the construction and assembly of the heat flux sensor. The resulting average heat flux profile for the test case is shown to be slightly higher in peak and longer in duration when compared with the results from the 1D analytical inversion, and this is attributed to contributions from the high thermal diffusivity constituents in the sensor. Furthermore, the negative heat flux at high load was not eliminated suggesting that factors other than lateral conduction may be affecting the measurement accuracy.

Heat Flux Measurements

1989 ◽  
Author(s):  
Curt H. Liebert ◽  
Donald H. Weikle
Keyword(s):  
Heat Flux ◽  
Surface Heat Flux ◽  
Space Shuttle ◽  
Turbine Blades ◽  
Flux Measurement ◽  
Surface Heat ◽  
Heat Flux Measurement ◽  
Flux Measurements ◽  
Durability Testing ◽  
Main Engine

This paper discusses a new automated, computer controlled heat flux measurement facility. Continuous transient and steady-state surface heat flux values varying from about 0.3 to 6 MW/m2 over a temperature range of 100 to 1200 K can be obtained in the facility. An application of this facility is the development of heat flux gauges for continuous fast transient surface heat flux measurement on turbine blades operating in space shuttle main engine turbopumps. The facility is also useful for durability testing at fast temperature transients.

Transient surface-heat-flux measurements in the exhaust of a SI engine

2007 ◽  
Vol 45 (1/2) ◽  
pp. 1 ◽  
Author(s):  
Mario Farrugia ◽  
Alex C. Alkidas ◽  
Brian P. Sangeorzan
Keyword(s):  
Heat Flux ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Si Engine ◽  
Flux Measurements

Unsteady convective surface heat flux measurements on cylinder for CFD code validation

Shock Waves ◽  
2003 ◽  
Vol 13 (5) ◽  
pp. 327-337 ◽  
Author(s):  
T. Saito ◽  
V. Menezes ◽  
T. Kuribayashi ◽  
M. Sun ◽  
G. Jagadeesh ◽  
...  
Keyword(s):  
Heat Flux ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Code Validation ◽  
Flux Measurements

scholarly journals Wall-Jet Turbulent Boundary Layer Heat Flux, Velocity, and Temperature Spectra and Time Scales

1996 ◽  
Author(s):  
David G. Holmberg ◽  
David J. Pestian
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Velocity Field ◽  
Turbulent Boundary Layer ◽  
Flat Plate ◽  
Surface Heat Flux ◽  
Free Stream ◽  
Surface Heat ◽  
Wall Jet ◽  
Time Resolved

The interactions of boundary layer flow temperature fluctuations (t′) and velocity fluctuations (u′, v′) together with surface heat flux fluctuations (q′) have been investigated experimentally in a flat plate turbulent boundary layer in order to better understand time-resolved interactions between flow unsteadiness and surface heat flux. A Heat Flux Microsensor (HFM) was placed on a heated flat plate beneath a turbulent wall jet, and a split-film boundary layer probe was traversed above it together with a cold-wire temperature probe. The recorded simultaneous time-resolved u′v′t′q′ data can be correlated across the boundary layer. Results indicate that wall heat transfer (both mean and fluctuating components) is controlled by the u′ fluctuating velocity field. In the presence of high free-stream turbulence (FST), the heat flux is largely controlled by free stream eddies of large size and energy reaching deep into the boundary layer, such that heat flux spectra can be determined from the free-stream velocity field. This is evidenced by uq coherence present across the boundary layer, as well as by similarity in heat flux and u velocity spectra, and by the presence of large velocity scales down to the nearest wall measuring location just above the laminar sublayer.

Analysis of significant measures for thermal conductivity

2020 ◽  
pp. 35-42
Author(s):  
Yuri P. Zarichnyak ◽  
Vyacheslav P. Khodunkov
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Measurement Method ◽  
Conductivity Measurement ◽  
Surface Heat ◽  
Measuring Instrument ◽  
New Class ◽  
Achievable Accuracy

The analysis of a new class of measuring instrument for heat quantities based on the use of multi-valued measures of heat conductivity of solids. For example, measuring thermal conductivity of solids shown the fallacy of the proposed approach and the illegality of the use of the principle of ambiguity to intensive thermal quantities. As a proof of the error of the approach, the relations for the thermal conductivities of the component elements of a heat pump that implements a multi-valued measure of thermal conductivity are given, and the limiting cases are considered. In two ways, it is established that the thermal conductivity of the specified measure does not depend on the value of the supplied heat flow. It is shown that the declared accuracy of the thermal conductivity measurement method does not correspond to the actual achievable accuracy values and the standard for the unit of surface heat flux density GET 172-2016. The estimation of the currently achievable accuracy of measuring the thermal conductivity of solids is given. The directions of further research and possible solutions to the problem are given.

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