Experimental study of the heat transfer from pipe walls to monatomic, diatomic, and triatomic gases at large temperature gradients
Heat transfer from wall to turbulent gas flow inside pipe at large temperature gradients
Elfimov, G. I.↗
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Results for “Temperature gradient”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Effect of wind and temperature gradients on received acoustic energy
The effect of refraction due to wind and temperature gradients on energy received from low flying aircraft is examined. A series of helicopter and jet flyby's were recorded with a microphone array on two separate days, each with distinctly different meteorological conditions. Energy in the 100 to 200 Hertz band is shown as a function of aircraft range from the array, and compared with the output of the Fast Field Program.
Brienzo, Richard K.↗
Induced pressure and temperature gradients in a plasma as a result of weak electric fields
Induced pressure and temperature gradients in plasma as result of weak electric fields
Meador, W. E.↗
Finite element study of plate buckling induced by spatial temperature gradients
Finite element analyses of thermal buckling of thin metallic plates with prescribed spatial temperature distributions are described. Thermally induced compressive membrane stresses and transverse plate displacement imperfections initiate plates buckling. A finite element formulation based on von Karman plate theory is presented. The resulting nonlinear equations are solved for incremental temperature increases by Newton-Raphson iteration. The computational method is used to investigate the buckling response of rectangular plates with steady and unsteady spatially varying temperature distributions. The role of initial plate imperfections and temperature distributions on the nonlinear response of plate displacements and stresses is described. The relatively high levels of stress induced by spatial temperature gradients should be considered carefully in the postbuckling design of panels for aerospace vehicles subjected to combined mechanical and thermal loads.
Thornton, Earl A.↗
Establishing allowable temperature gradients for tungsten-uranium dioxide fuel elements using experimental cyclic strain data
Establishing allowable temperature gradients for tungsten-uranium dioxide fuel elements using experimental cyclic strain data
Fiero, I. B.↗
Electroconvective instability with a stabilizing temperature gradient. 2 - Experimental results
Threshold voltage measurements on electric field instability in fluid with stabilizing temperature gradient
Turnbull, R. J.↗
Electroconvective instability with a stabilizing temperature gradient. 1 - Theory
Perturbation theory for predicting electric field induced instability in fluid with stabilizing temperature gradients
Turnbull, R. J.↗
Atmospheric temperature gradients related to clear air turbulence in the upper troposphere and lower stratosphere
Relationship between atmospheric temperature gradients and clear air turbulence of lower atmosphere
Kadlec, P. W.↗
Stresses and deformations in composite tubes due to a circumferential temperature gradient
A linear elasticity solution for determining the response of composite tubes subjected to a circumferential temperature gradient is presented. Numerical examples are used to show that, in a single layer tube, fiber orientation strongly influences response. When the fibers are aligned axially, all stress components in the tube are small. When the fibers are aligned circumferentially, the hoop stress becomes large. This difference in behavior is due to the large difference between the radial and circumferential coefficients of thermal expansion when the fibers are oriented circumferentially. In multilayer tubes, stresses are quite high and just two constants characterize the overall bending and axial deformations of the tubes.
Hyer, M. W.↗
Evaluation of Temperature Gradients During Cure of a Thick Carbon Fiber/Epoxy Composite
The purpose of this study is to evaluate the development of thermal gradients throughout thick (1") carbon fiber composites and determine the effect of internal temperature distribution during cure on the observed mechanical properties in those composites. Composites up to 1.5" thick (56 plies) were fabricated with T700S/TC380 braided prepreg from Tencate following a modified vacuum bag layup procedure to include embedded thermocouples within the plies of the composite. Composite panels were cured in a programmable oven with thermocouple reading embedded throughout the panel thickness. Maximum temperature gradients measured between regions of the composite did not exceed 10 degrees C for any given composite thickness. The most significant temperature variation was measured between the mid-thickness plies and the tool-side surface plies. Although through thickness temperature variation during cure was small, a measureable variation in coupon glass transition temperature was recorded between the tool side plies and the remainder of the part, prior to post cure. Thermal and mechanical behavior of coupons taken from segments through the thickness of the part were comparable following a post-cure cycle.
Miller, Sandi↗
A current generation by Compton scattering in a relativistic plasma with velocity shear and temperature gradient
Current generation by Thomson scattering in a non-relativistic plasma with the velocity shear and the temperature gradient (Hinata and Daneshvar, 1983) is extended to a relativistic plasma by replacing Thomson cross section by the Klein-Nishina formula. Because of the energy dependence of the cross-section, a numerical rather than analytic result is presented. The present calculation may be applied to a supernova implosion where the temperature may reach several MeV and a strong differential rotation is expected. It may also find applications in the early universe, and laser-pellet interaction.
Hinata, S.↗
Characterization of thermotropism in primary roots of maize: dependence on temperature and temperature gradient, and interaction with gravitropism
Thermotropism in primary roots of Zea mays L. was studied with respect to gradient strength (degrees C cm-1), temperature of exposure within a gradient, pre-treatment temperature, and gravitropic stimulation. The magnitude of the response decreased with gradient strength. Maximum thermotropism was independent of gradient strength and pre-treatment temperature. The range of temperature for positive and negative thermotropism did not change with pre-treatment temperature. However, the exact range of temperatures for positive and negative thermotropism varied with gradient strengths. In general, temperatures of exposure lower than 25 degrees C resulted in positive tropic responses while temperatures of exposure of 39 degrees C or more resulted in negative tropic responses. Thermotropism was shown to modify and reverse the normal gravitropic curvature of a horizontal root when thermal gradients were applied opposite the 1 g vector. It is concluded that root thermotropism is a consequence of thermal sensing and that the curvature of the primary root results from the interaction of the thermal and gravitational sensing systems.
Non-NASA Center↗
Electroconvective instability with a stabilizing temperature gradient. II - Experimental results.
Electroconvective instability produced by uniform electric field in poorly conducting fluid under stabilizing vertical temperature gradient, noting heat flow increase
Turnbull, R. J.↗
Effect of the temperature gradient on the drift instabilities in a high-beta collisionless plasma
Inhomogeneous high-beta collisionless plasma temperature gradient effects on ion-acoustic and Alfvenic drift instabilities
Hung, R. J.↗
Infrared limb scanning in the presence of horizontal temperature gradients - An operational approach
Simulation and analysis of IR limb radiance obtained by a satellite-borne IR limb scanner have demonstrated that horizontal temperature gradients in the atmosphere play an important role in limiting the accuracy of retrieved temperature and constituents below approximately 25 km. A simple operational approach to converting these observed radiances to equivalent spherical radiances is developed which preserves the advantages of the sphericity assumption in the inversion process.
Roewe, D. A.↗
Temperature Gradients on the Cell Wall in the Critical Viscosity Experiment
Because of the diverging susceptibility delta rho/delta Tau near the liquid-vapor critical point, temperature gradients must be kept small to maintain adequate sample homogeneity. In our Science Requirements Document we paid particular attention to radial density gradients caused by equilibration of the xenon sample. Axial density gradients were addressed through the requirement that the cell's copper wall have a gradient less than 22 microK/m. This report re-examines the cell wall's temperature distribution in more detail by estimating all known significant contributions to temperature differences on the cell's wall.
Berg, Robert F.↗
Electron temperature gradient instability and transport analysis in NSTX and NSTX-U plasmas
Extensive linear and nonlinear simulations to study electron temperature gradient (ETG) stability and thermal transport in National Spherical Torus Experiment (NSTX) and NSTX-U plasmas were performed using the fully electromagnetic gyrokinetic code CGYRO. Linear simulations were performed to determine ETG thresholds in different discharges, showing that ETG modes in spherical tokamaks can present different scalings compared to conventional aspect-ratio tokamaks. Nonlinear gyrokinetic simulations were conducted for selected cases to calculate electron thermal transport and compare to experimental values. Results are also compared with those of ETG modes in the multi-mode model and the Trapped-Gyro-Landau-Fluid reduced model codes, to better understand their applicability in spherical tokamaks.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Global gyro-kinetic ion temperature gradient and trapped electron mode turbulence modelling in X -point geometry in negative and positive triangularity
Comparative modelling of ion temperature gradient (ITG)/trapped electron mode (TEM) turbulence in negative (NT) and positive (PT) triangularity plasma shapes was done using the nonlinear global full-f gyrokinetic particle code JOREK-GK in the realistic X-point tokamak geometry including the Scrape Off Layer (SOL) for TCV and DIII-D parameters. A comparison of JOREK-GK code with the gyrokinetic codes GS2 and GENE was done using NT/PT triangularity TCV L-modes parameters showing good agreement between codes in linear growth rates and clear beneficial effect of NT as compared to PT. Global non-linear modelling of the ITG/TEM saturated turbulence for realistic DIII-D NT pulses was done and compared with numerically constructed PT equilibrium with the same plasma profiles. Existence of longer correlation length of density fluctuations in PT compared to NT was demonstrated. Stronger and more sheared zonal flows are generated via Reynolds stress in NT compared to PT. These factors are stabilizing for TEM/ITG turbulence in NT and lead to smaller heat fluxes and heat conductivities in NT compared to PT configuration. Weak dependence of plasma confinement on collisionality and plasma rotation was found in modelling of DIII-D NT shots similar to the experiment. The confinement scaling with normalized ion gyro-radius ρ* was estimated both for NT and PT. Bohm-like scaling was obtained in both configurations, however with better confinement for NT compared to PT which could be favourable factor for reactor size machines.
ITG↗