Verification and Validation Studies for Laminar Hypersonic Flow Over a Blunted Cone and a Flat Plate

2006 ◽  
Author(s):  
S. Gokaltun ◽  
P. V. Skudarnov ◽  
C. X. Lin ◽  
Hugh Thornburg
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Hypersonic Flow ◽  
Surface Pressure ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Numerical Results ◽  
Verification And Validation

In this paper, verification and validation analysis for laminar hypersonic flow fields is presented. The simulations include a Mach 8 flow of calorically perfect gas over a spherically blunted cone and a Mach 14 flow over a flat plate. Numerical results were obtained using the finite volume method on structured grids. The verification of the numerical solutions was performed by calculating the Grid Convergence Index (GCI) for both test cases. A set of three different grids is used to calculate the discretization uncertainty, where each grid was generated by doubling the number of cells in each direction of the coarser grid. The value of GCI allows calculating the observed order of accuracy of the numerical method for local values of surface pressure at various points and the net drag force for the blunted cone case and for the local heat transfer coefficient for the flat plate case. The error band was observed to be 2.4% for the surface pressure in the blunted cone problem and 0.5% for the heat transfer coefficient in the flat plate problem. Finally the numerical results were validated with experimental data using the local surface pressure measurements for the hypersonic cone and the local heat transfer coefficient measurements for the hypersonic flat plate.

Effects of Cooling Films on the Heat Transfer Coefficient on a Flat Plate With Zero Mainstream Pressure Gradient

1985 ◽  
Vol 107 (1) ◽  
pp. 105-110 ◽  
Author(s):  
N. Hay ◽  
D. Lampard ◽  
C. L. Saluja
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Polymer Surface ◽  
Flux Ratio ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Coefficients ◽  
The Heat Transfer Coefficient

The influence of injection of cooling films through a row of holes on the heat transfer coefficient on a flat plate is investigated for a range of mass flux ratio using a heat-mass transfer analogy. Injection angles of 35 deg and 90 deg are covered. The experimental technique employed uses a swollen polymer surface and laser holographic interferometry. The results presented show the change in local heat transfer coefficient over the no-injection values at the centerline and off-centerline locations for various streamwise stations. The effect of injection on laterally averaged heat transfer coefficients is also assessed.

Expansion of a Modified Transient Liquid Crystal Method for Thin Plates of Different Materials

2004 ◽  
Author(s):  
Alison K. Reed ◽  
Kenneth Van Treuren
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Liquid Crystal ◽  
Temperature Distribution ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Plexiglas Plate ◽  
Coefficient Distribution

The purpose of this research is to apply a modified transient liquid crystal method to a thin flat plate to determine the local temperature distribution and heat transfer coefficient. This research examines three different plates: 1) 1/8 inch thick Plexiglas plate, 2) 1/2 inch thick Plexiglas plate, and 3) 1/8 inch thick aluminum plate. Each plate is approximately 6 inches in length by 3 inches in width. The temperature distributions on a flat plate are viewed over time using a liquid crystal thermography (LCT) technique. The plates are coated with a wide band liquid crystal (R30C5W) and fixed in a vertically oriented wind tunnel. For any thickness plate, the speed of the tunnel was adjusted for a Reynolds number within the range of approximately 22100 and 23100. For the theoretical analysis, the thin flat plate used a convective surface boundary condition and a 2-D transient finite-differencing conduction scheme. An initial local heat transfer coefficient distribution is selected based upon flat plate theory and is used to calculate an initial streamwise temperature distribution. The local heat transfer coefficient distribution is readjusted until the theoretical temperature distribution matches the experimental temperature distribution over the center surface of the plate. This technique allows a wider application of transient LCT and for heat transfer coefficients to be mapped on thin surfaces of different materials.

Local Heat Transfer Measurements in Turbulent Flow Around a 180-deg Pipe Bend

1987 ◽  
Vol 109 (1) ◽  
pp. 43-48 ◽  
Author(s):  
J. W. Baughn ◽  
H. Iacovides ◽  
D. C. Jackson ◽  
B. E. Launder
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Turbulent Flow ◽  
Transfer Coefficient ◽  
Secondary Flow ◽  
Local Heat Transfer ◽  
Reynolds Numbers ◽  
Local Heat ◽  
Pipe Bend ◽  
Streamline Curvature

The paper reports extensive connective heat transfer data for turbulent flow of air around a U-bend with a ratio of bend radius:pipe diameter of 3.375:1. Experiments cover Reynolds numbers from 2 × 104 to 1.1 × 105. Measurements of local heat transfer coefficient are made at six stations and at five circumferential positions at each station. At Re = 6 × 104 a detailed mapping of the temperature field within the air is made at the same stations. The experiment duplicates the flow configuration for which Azzola and Humphrey [3] have recently reported laser-Doppler measurements of the mean and turbulent velocity field. The measurements show a strong augmentation of heat transfer coefficient on the outside of the bend and relatively low levels on the inside associated with the combined effects of secondary flow and the amplification/suppression of turbulent mixing by streamline curvature. The peak level of Nu occurs halfway around the bend at which position the heat transfer coefficient on the outside is about three times that on the inside. Another feature of interest is that a strongly nonuniform Nu persists six diameters downstream of the bend even though secondary flow and streamline curvature are negligible there. At the entry to the bend there are signs of partial laminarization on the inside of the bend, an effect that is more pronounced at lower Reynolds numbers.

An Experimental Study of High Rayleigh Number Mixed Convection in a Rectangular Enclosure With Restricted Inlet and Outlet Openings

1987 ◽  
Vol 109 (2) ◽  
pp. 446-453 ◽  
Author(s):  
L. Neiswanger ◽  
G. A. Johnson ◽  
V. P. Carey
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Rayleigh Number ◽  
Mixed Convection ◽  
Transfer Coefficient ◽  
Heated Surface ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Test Fluid ◽  
Rectangular Enclosure

Measured local heat transfer data and the results of flow visualization studies are reported for cross-flow mixed convection in a rectangular enclosure with restricted inlet and outlet openings at high Rayleigh number. In this study, experiments using water as the test fluid were conducted in a small-scale test section with uniformly heated vertical side walls and an adiabatic top and bottom. As the flow rate through the enclosure increased, the enhancement of heat transfer, above that for natural convection alone, also increased. The variation of the local heat transfer coefficient over the heated surface was found to be strongly affected by the recirculation of portions of the forced flow within the enclosure. Mean heat transfer coefficients are also presented which were calculated by averaging the measured local values over the heated surface. A correlation for the mean heat transfer coefficient is also proposed which agrees very well with the experimentally determined values. A method of predicting the flow regime in this geometry for specified heating and flow conditions is also discussed.

Local and Average Heat Transfer Characteristics for a Disk Situated Perpendicular to a Uniform Flow

1985 ◽  
Vol 107 (2) ◽  
pp. 321-326 ◽  
Author(s):  
E. M. Sparrow ◽  
G. T. Geiger
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Stagnation Point ◽  
Radial Distance ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Average Heat ◽  
Radial Profiles

Wind tunnel experiments were performed to determine both the average heat transfer coefficient and the radial distribution of the local heat transfer coefficient for a circular disk facing a uniform oncoming flow. The experiments covered the range of Reynolds numbers Re from 5000 to 50,000 and were performed using the naphthalene sublimation technique. To complement the experiments, an analysis incorporating both potential flow theory and boundary layer theory was used to predict the stagnation point heat transfer. The measured average Nusselt numbers definitively resolved a deep disparity between information from the literature and yielded the correlation Nu = 1.05 Pr0.36 Re1/2. The radial distributions of the local heat transfer coefficient were found to be congruent when they were normalized by Re1/2. Furthermore, the radial profiles showed that the local coefficient takes on its minimum value at the stagnation point and increases with increasing radial distance from the center of the disk. At the outer edge of the disk, the coefficient is more than twice as large as that at the stagnation point. The theoretical predictions of the stagnation point heat transfer exceeded the experimental values by about 6 percent. This overprediction is similar to that which occurs for cylinders and spheres in crossflow.

An Investigation of Local Heat Transfer during Grinding Process—Effects of Porosity of Grinding Wheel

1979 ◽  
Vol 101 (2) ◽  
pp. 97-103 ◽  
Author(s):  
Y. Saito ◽  
N. Nishiwaki ◽  
Y. Ito
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Thermal Boundary Condition ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Workpiece Surface

The thermal boundary condition around the workpiece surface is one of important factors to analyze the thermal deformation of a workpiece, which is in close relation to the machining, accuracy of grinding. The heat dissipation from the workpiece surface which is influenced by the flow pattern, may govern this thermal boundary condition. In consequence, it is necessary to clarify the convection heat transfer coefficient and the flow pattern of air and/or grinding fluid around surroundings of a rotating grinding wheel and of a workpiece. Here experiments were carried out in a surface grinding process to measure the flow velocity, wall pressure and local heat transfer by changing the porosity of the grinding wheel. The air blowing out from the grinding wheel which is effected by the porosity may be considered to have large influences on the local heat transfer coefficient, which is found to be neither symmetric nor uniform over the workpiece surface.

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