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Laminar boundary-layer heat transfer and shear stress predictions from similarity solutions, emphasizing large free-stream velocity gradients and highly cooled walls
Laminar boundary-layer heat transfer and shear stress predictions from similarity solutions, emphasizing large free-stream velocity gradients and highly cooled walls
Laminar heat transfer distributions for blunted- cone, cone frustum reentry configuration at hypersonic speed using Reynolds number
Low & high prandtl number approaches for heat transfer in laminar flow of incompressible fluids with constant material properties
Heat transfer results are presented for laminar, transition, and turbulent boundary layers for a Mach number of 0.12 with gas temperatures of 425 K and 1000 K over a flat plate at room temperature. The measurements were made in air for a Reynolds number range of 600 to 6 million. The heat transfer measurements were conducted in a 70-ft long, 4 in. diameter shock tube. Reflecting wedges were used to reflect the incident shock wave to produce a flow Mach number of 0.12 behind the reflected shock wave. Thin film platinum heat gages were mounted on the plate surface to measure the local heat flux. The laminar results for gas temperatures of 425 K to 1000 K agree well with theory. The turbulent results are also close to incompressible theory, with the 1000 K flow case being slightly higher. The transition results lie between the laminar and turbulent predictions.
Laminar convective heat transfer and boundary layer equations for cones at escape velocity
Results are presented of a theoretical and experimental investigation of heat transfer involving laminar natural convection of fluids enclosed between parallel walls oriented in the direction of the body force, where one wall is heated uniformly, and the other is cooled uniformly. For the experimental work, parallel walls were simulated by using an annulus with an inner-to-outer diameter ratio near 1. The results of the theoretical investigation are presented in the form of equations for the velocity and temperature profiles and the ratio of actual temperature drop across the fluid to the temperature drop for pure conduction. No experimental measurements were made of the velocity and temperature profiles, but the experimental results are compared with theory on the basis of the ratio of the actual temperature drop to the temperature drop for pure conduction. Good agreement was obtained between theory and experiment for axial temperature gradients of 10 degrees F. per foot or larger.
Prediction of heat transfer and shear stress from laminar boundary layer
Superimposed free vortex swirl effect on flow and heat transfer in three dimensional axisymmetric laminar boundary layer
Laminar heating distributions were measured at hypersonic-hypervelocity flow conditions on a 1.9-percent-scale model of an aeroassisted vehiclee proposed for missions to a number of planets. This vehicle is a spherically blunted, 12.84/7deg biconic with the fore-cone axis bent upward 7 deg relative to the aft-cone axis to provide selftrim capability. Also tested was a straight biconic (i.e., without nose bend) with the same nose radius and half-angles as the bent-nose biconic. These measurements were made in the Langley Expansion Tube at free-stream velocities from 4.5 to 6.9 km/sec and Mach numbers from 6.0 to 9.0 with helium, nitrogen, air, and carbon dioxide test gases. The range of calculated thermochemical equilibrium normal-shock density ratios for these four test gases was 4 to 19. Angles of attack, referenced to the aft-cone, varied from 0 to 20 deg. Heating distributions predicted with a parabolized Navier-Stokes (PNS) code were compared with measurement for helium and air test gases. Measured windward and leeward heating levels were generally underpredicted by the PNS code for both test gases, and agreement was poorer on the leeward side than on the windward side.
The paper summarizes results of theoretical and experimental investigations of wall temperature change and heat transfer in the laminar boundary layer formed within noncentered unsteady expansion waves in shock tubes. The study is restricted to a class of noncentered plane waves which have one key feature in common with centered waves, i.e., the first derivatives of the inviscid flow quantities have values or are discontinuous at the wavehead. The wall temperature is calculated implicitly by matching the local heat transfer rates of gas and wall thermal boundary layers. Experimentally, the wall temperature was measured using a thin-film resistance thermometer and heat transfer was then deduced using a one-dimensional unsteady heat conduction equation.
Numerical solutions of compressible laminar boundary layer heat transfer and pressure drop of gas in uniformly heated tube
Thermochemical effects of foreign planetary atmospheres upon laminar heat transfer in hypersonic stagnation region - gas dynamics
Analysis of laminar fully developed heat transfer in thin rectangular channels with fuel loading removed from the corners
Computational Fluid Dynamics (CFD) codes are routinely used to predict the flowfield and the heating environment around complex reentry configurations. At hypervelocities, where the velocity is greater than 3 km/sec, the AFWAL version of the blunt body code predicts the correct surface pressure distributions but underpredicts laminar wall heat fluxes. This study was performed to determine the reasons for the underprediction. The computer code chosen solves thin-layer Navier-Stokes equations in a time-asymptotic manner and assumes a constant isentropic exponent. Flowfields around a spherical configuration at various entry velocities are computed. The computed pressure distributions agree well with the tabulated, inviscid results of Lyubimov and Rusanov for entry velocities ranging from 0.6 to 5.92 km/sec. At hypervelocities, the calculated stagnation point heat transfer rates were lower by roughly fifty percent when compared to engineering correlations available in the literature. Good comparisons between heat transfer rates are obtained at hypervelocity entry conditions provided the CFD code is modified to include equilibrium air properties.
Convective heat transfer in thin rectangular channels commonly found in nuclear reactor fuel assemblies
A variational method is presented for solving eigenvalue problems which arise in connection with the analysis of convective heat transfer in the thermal entrance region of ducts. Consideration is given, to both situations where the temperature profile depends upon one cross-sectional coordinate (e.g. circular tube) or upon two cross-sectional coordinates (e.g. rectangular duct). The variational method is illustrated and verified by application to laminar heat transfer in a circular tube and a parallel-plate channel, and good agreement with existing numerical solutions is attained. Then, application is made to laminar heat transfer in a square duct as a check, an alternate computation for the square duct is made using a method indicated by Misaps and Pohihausen. The variational method can, in principle, also be applied to problems in turbulent heat transfer.
Reference-point results applied to variations in laminar heat transfer to total vehicle over range of vehicle attitudes and associated trajectories