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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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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Surface temperature distribution along a thin liquid layer due to thermocapillary convection

The surface temperature distributions due to thermocapillary convections in a thin liquid layer with heat fluxes imposed on the free surface were investigated. The nondimensional analysis predicts that, when convection is important, the characteristics length scale in the flow direction L, and the characteristic temperature difference delta T sub o can be represented by L and delta T sub o approx. (A2Ma)/1/4 delta T sub R, respectively, where L sub R and delta sub R are the reference scales used in the conduction dominant situations with A denoting the aspect ratio and Ma the Marangoni number. Having L and delta sub o defined, the global surface temperature gradient delta sub o/L, the global thermocapillary driving force, and other interesting features can be determined. Numerical calculations involving a Gaussian heat flux distribution are presented to justify these two relations.

Lai, C. L.↗
NASA NTRS1985

Surface temperature distribution along a thin liquid layer due to thermocapillary convection

The surface temperature distributions due to thermocapillary convections in a thin liquid layer with heat fluxes imposed on the free surface were investigated. The nondimensional analysis predicts that, when convection is important, the characteristics length scale in the flow direction L, and the characteristic temperature difference delta T sub o can be represented by L and delta T sub o approx. (A2Ma)/1/4 delta T sub R, respectively, where L sub R and delta sub R are the reference scales used in the conduction dominant situations with A denoting the aspect ratio and Ma the Marangoni number. Having L and delta sub o defined, the global surface temperature gradient delta sub o/L, the global thermocapillary driving force, and other interesting features can be determined. Numerical calculations involving a Gaussian heat flux distribution are presented to justify these two relations.

Lai, C.-L.↗
NASA NTRS1947

Computed Temperature Distribution and Cooling of Solid Gas-Turbine Blades

Computations were made to determine the temperature distribution and cooling of solid gas-turbine blades.A range of temperatures was used from 1500 degrees to 2500 degrees F, blade-root temperatures from 100 degrees to 1000 degrees F, blade thermal conductivity from 8 to 220 BTU/(hr)(sq ft)(degrees F/ft), and net gas to metal heat transfer coefficients from 75 to 250 BTU/(hr)(sq ft)(degrees F).

Reuter, J. George↗
NASA NTRS1974

Global temperature distributions from OGO-6 6300 A airglow measurements

The OGO-6 6300 A airglow temperature measurements have been used to develop models of the global temperature distributions under solstice and equinox conditions for the altitude region from 240 to 300 km and for times ranging from dawn in this altitude region to shortly after sunset. The distributions are compared with models derived from satellite orbital decay and incoherent scatter sounding. The seasonal variation of the temperature as a function of latitude is shown to be very different from that derived from static diffusion models with constant boundary conditions.

Blamont, J. E.↗
NASA NTRS1976

Rocket engine thrust chamber wall temperature distribution calculation and analysis

An analytical computational concept is presented which predicts the temperature profiles along a regeneratively cooled thrust chamber wall on the hot gas side and on the coolant side, and also the coolant bulk temperature profile. The computational model is based upon a coupling of the boundary layer heat transfer process with the heat transfer process through the chamber wall and the coolant flow heat absorption. The calculation is started with approximate temperature distributions for the hot gas side wall and the coolant flow. The iteration process of the computer program is terminated when the total heat transfer rates from the hot gas boundary layer to the wall and from the wall to the coolant are equal. The computer program for the integration of regenerative cooling process to a thrust chamber is kept general such that this program can be used with any boundary layer analysis computer program for temperature profile and heat transfer studies. A sample application of this concept is shown by using a boundary layer analysis program for the RL10 rocket engine thrust chamber.

Saha, H.↗
NASA NTRS1975

Analysis of the effects on life of leading-edge holes in an airfoil subjected to arbitrary spanwise and chordwise temperature distributions

The effects of temperature gradients, cooling-hole rim and bulk metal temperatures, and mechanical stress were investigated by using a finite-element structural analysis of a symmetrical airfoil with and without leading-edge holes. The results indicate that leading-edge film cooling is beneficial when large chordwise temperature gradients exist and if the cooling-hole rim temperatures are above the bulk metal temperature. The effects of film cooling at other locations on the airfoil were not considered, and the relative merits of convection or film cooling at the leading edge, in terms of allowable turbine inlet temperature or coolant flow requirements, were not evaluated.

Kaufman, A.↗
NASA NTRS1985

A color graphics presentation of the Space Shuttle Orbiter windward surface entry temperature distribution

The windward surface temperature response measured during the fifth entry of the Space Shuttle Columbia is presented as solid filled color contour plots. These plots show the data from 92 instruments, at selected points in time, in a manner which makes the temperature extremes and gradients immediately obvious. Several physical phenomena, such as separated flow caused by the deflected body flap, local heating at the elevon-elevon gap, an overview of the propagation of boundary-layer transition over the Orbiter windward surface, and the thermal response of eight catalytically coated tiles, can be observed or inferred from the displayed temperatures. In addition, the maximums from each instrument have been contoured and are presented with a companion plot showing the percentage of surface area covered by each contour level. Also, the flight data are presented using the colors which correspond to the surface emittance as a function of temperature. To show the temperature transients, a computer-generated movie has been produced showing the temperature contours from 100 s to 1500 s after entry interface.

Martin, F. W., Jr.↗
NASA NTRS1988

An analysis of the temperature distribution in finite solid-state laser rods

An expression for the time-dependent temperature distribution in a finite solid-state laser rod, for an arbitrary distribution of pump energy, has been derived. The specific case of end pumping by circular (constant) or Gaussian beams is included. This formulation was used to predict the time evolution of temperature in Ti:sapphire laser rods and in Nd:YAG rods of specific dimensions.

Farrukh, Usamah O.↗
NASA NTRS1989

Temperature distribution of dust in luminous IRAS galaxies

Work is currently in progress to obtain temperature distributions of dust in the most infrared-luminous galaxies. The results presented are of a preliminary nature, representing a zeroth-order approximation. The objects which have been analyzed so far are all galaxies from the Infrared Astronomy Satellite (IRAS) Bright Galaxy Sample with infrared luminosities L sub IR greater than or equal to 10(exp 11) solar luminosity. They are: Arp 220, Mrk 231, Mrk 273, NGC 1614, NGC 3690, NGC 6285/6, and Zw 049.057. The analysis utilized 3.7 micron data from the Palomar 5 m Hale telescope, IRAS data at 12, 25, 60, and 100 microns, and 1 mm continuum data from the CalTech Submillimeter Observatory on Mauna Kea.

Carico, David P.↗
NASA NTRS1961

An Analysis of Exact and Approximate Equations for the Temperature Distribution in an Insulated Thick Skin Subjected to Aerodynamic Heating

The problem of calculating the temperature distribution in an insulated slab is investigated. Exact and approximate solutions are obtained, and the results are compared to determine the ranges of applicability of the approximations. The approximations are found to be within 5 percent of the exact solution when the ratio of the thermal capacitance of the metal to that of the insulation and the ratio of the conductance of the metal to that of the insulation are sufficiently large. The roots of the characteristic equation of the exact solution are generally applicable to the two-slab heat-transfer problem and are tabulated up to the first nine roots.

Harris, Robert S., Jr.↗
NASA NTRS1993

Temperature distribution in side- and end-pumped laser crystal rods - Temporal and spatial variations

Knowledge of the temperature distribution of laser rods end pumped by laser diodes or other laser systems is relevant when thermal stress and crystal damage are expected. The temperature of a multipulsed or continuously pumped laser rod is given as a double-series expression and as a function of time. The mathematical model considers all surface cooling rates, the spatial and temporal variations of the pump beam, and the specific heat and thermal conductivity of the rod material. This eigenfunction expansion representation was employed to predict the spatial and time-dependent quasi-steady-state temperature in Ti:sapphire, Nd:YAG, and Cr:LiSAF laser rods of specific dimensions.

Farrukh, Usamah O.↗
NASA NTRS1995

Effect of velocity and temperature distribution at the hole exit on film cooling of turbine blades

An existing three-dimensional Navier-Stokes code, modified to include film cooling considerations, has been used to study the effect of coolant velocity and temperature distribution at the hole exit on the heat transfer coefficient on three-film-cooled turbine blades, namely, the C3X vane, the VKI rotor, and the ACE rotor. Results are also compared with the experimental data for all the blades. Moreover, Mayle's transition criterion, Forest's model for augmentation of leading edge heat transfer due to freestream turbulence, and Crawford's model for augmentation of eddy viscosity due to film cooling are used. Use of Mayle's and Forest's models is relevant only for the ACE rotor due to the absence of showerhead cooling on this rotor. It is found that, in some cases, the effect of distribution of coolant velocity and temperature at the hole exit can be as much as 60% on the heat transfer coefficient at the blade suction surface, and 50% at the pressure surface. Also, different effects are observed on the pressure and suction surface depending upon the blade as well as upon the hole shape, conical or cylindrical.

Garg, Vijay K.↗
NASA NTRS1947

Cooling of Gas Turbines, IV - Calculated Temperature Distribution in the Trailing Part of a Turbine Blade Using Direct Liquid Cooling

A theoretical analysis of the temperature distribution through the trailing portion of a blade near the coolant passages of liquid cooled gas turbines was made. The analysis was applied to obtain the hot spot temperatures at the trailing edge and influence of design variables. The effective gas temperature was varied from 2000 degrees to 5000 degrees F in each investigation.

Brown, W. Byron↗
NASA NTRS2004

Temperature Distributions in Hollow Cathode Emitters

Life-limiting processes in hollow cathodes are determined largely by the temperature of the emitter. To support development of cathode life models we have developed a noncontact temperature measurement technique which employs a stepper motor-driven fiber optic probe. The probe is driven inside the hollow cathode and collects light radiated by the hot interior surface of the emitter. Ratio pyrometry is used determine the axial temperature profile. Thermocouples on the orifice plate provide measurements ofthe external temperature during cathode operation and are used to calibrate the pyrometer system in situ with a small oven enclosing the externally heated cathode. Initial measurements of the temperature distribution in a hollow cathode with the same geometry as a cathode that failed after operating at 12 A emission current for 27800 hours are discussed.

ratio pyrometer system↗