Variation Of Gas Temperature Research Articles

Measurement of rapidly varying gas temperatures in an unsteady flow

For a thin thermometer having no radial temperature gradient but showing a certain thermal inertia the displacement of mean temperature related to the mean temperature of gas is determined together with the temperature record fundamental and higher harmonics in the case when both the measured temperature and the heat-transfer coefficient are varying periodically at the same frequency having different phase displacements. The effect of thermal conduction along the thermometer is taken into consideration.

The effect of diurnal temperature changes on the F2-layer

The paper describes time-varying solutions obtained for the F2-region continuity equation under conditions of thermal non-equilibrium. An isothermal model atmosphere is used and the continuity equation includes a movement term due to temperature variations of the neutral atmosphere. It is found that a decrease of electron temperature at sunset does not produce a ‘post-sunset’ increase of electron density. The ‘seasonal anomaly’ in F2-region electron densities also cannot be explained in terms of temperature variations. It is shown that variations of electron temperature are important in determining electron density, but the height of maximum electron density depends on variations of the neutral gas temperature.

Reflection of a Shock Wave at a Surface

A new finite difference method is employed in obtaining numerical solutions for the complete Navier-Stokes equations. The physical problem treated is the time-dependent propagation of a one-dimensional disturbance, which is produced by the forward motion of a piston through a compressible, viscous, thermally conducting, perfect diatomic gas and its subsequent reflection at a material surface. Two values of disturbance strength are considered, including weak and strong shock waves. The quantities determined include the variation of gas velocity, pressure, density, and temperature as a function of time and distance. In addition, the heat transfer rate and the pressure, which are of considerable interest in the interpretation of shock tube phenomena, are determined at the surface during the period of reflection of the shock wave.

Determination of Electron Densities in dc Discharges with the Aid of Probes

Oscillation-free arcs were operated at 1.4 or 1.0 A in a tube with a 34 mm i.d. and a filling pressure of 7 Torr for neon, and 1–2 Torr for Ar, Kr, and Xe. Probes, including one moved radially, were used to determine positive column characteristics, particularly the axial electron density n0. In each computation, corrections were made for the radial variation of gas temperature. The electron density distribution, n/n0 vs r, was not determined with the desired accuracy. Disturbance of the discharge made the probe current rise too rapidly as the probe approached the axis. After due allowance for errors, n/n0 in the neon discharge seemed to vary roughly as the Bessel function J0 (2.33 r/R), where R=radius of positive column. With the heavier gases there was some evidence of a slight constriction of the discharge, presumably due to dissociative recombination of molecular ions formed in the cooler regions near the tube wall. Plausible curves for n/n0 vs r can be drawn to make n0 values computed from the ambipolar flow of charge agree roughly with those derived from the current, at space potential, to a very small probe at the axis of the tube. Ion current to this probe gave values that were usually somewhat larger, and depended on the probe voltage. Collisions with ions made the electron mobility calculated for the Ar discharge only 45% of that based on atomic collisions alone. With Kr this value was 60%. Computed arc currents ranged from 0.63 to 1.53 times the actual values.

The effect of gas flow patterns on radiative transfer in cylindrical furnaces

The prediction of performance of industrial furnaces is conventionally estimated by making gross assumptions as to the effect of temperature variations in the gas. The zone method of allowing for the effect, on radiative transfer, of the temperature variation in furnace enclosures has been applied to the problem of interaction between radiation and other modes of heat transfer. The effect of different flow patterns on the gas temperature-field and wall-flux distribution in a cylindrical furnace has been examined by use of the following flow models : plug flow ; parabolic velocity profiles ; ducted-jet flow (axial feed) with recirculation rates of 0, 1, and 11 times the flue-gas flow rate. A sixteenfold range of diameters and firing densities was studied. The reduced efficiencies were correlated, for a fixed surface temperature and for each of the flow models, in terms of a reduced firing rate. The wide range of heat flux distribution patterns found in the study emphasizes the need to include allowance for gas temperature variation in any furnace analysis in which the heat flux pattern is important.

Heat Transfer by Combined Forced Convection and Thermal Radiation in a Heated Tube

An analysis is made to study the heat exchange by combined forced convection and thermal radiation in a tube when there is a specified heat flux imposed at the tube wall. The gas flowing in the tube is assumed transparent to radiation, so that the radiation which is included takes place between the elements of the internal tube surface and between this tube surface and the environment at each end of the tube. The inside surface of the tube is a black emitter and the outside is assumed perfectly insulated. The heat-transfer coefficient for convection alone from the tube wall to the gas is assumed constant. The energy equation governing the heat exchange is solved by two methods which provide results that are in good agreement with each other. Numerical examples of the wall and gas-temperature variations along the tube show the influence of the system parameters such as inlet gas temperature, tube length, and convective heat-transfer coefficient. A simple method is outlined, which can be used under some conditions to obtain an approximate wall-temperature distribution.

259. Selective modulation of radiation by periodical variation of gas temperature: A.O. Sall, Optics and Spectroscopy, VII, 355–356, Oct. 1959

259. Selective modulation of radiation by periodical variation of gas temperature: A.O. Sall, Optics and Spectroscopy, VII, 355–356, Oct. 1959

Combustion in Liquid-Fuel Rocket Motors

SummaryThe paper provides a simplified picture of the processes occurring in liquid bi-propellant rocket motors. Droplet vaporisation, chemical reaction, and drag between gas and droplet are considered for a one-dimensional model. Quantitative theoretical results are presented for the variation of droplet size, droplet velocity, gas temperature and gas velocity within the chamber, particular attention being paid to the calculation of L*. The theory is applied to the German V2 rocket motor. Practical conclusions from, and extensions to, the theory are discussed.

Unsteady state heat transfer in stationary packed beds

AbstractA new solution is presented of the differential equations describing unsteady state heat transfer in stationary beds of small granular solid particles through which a fluid is flowing. Arbitrary initial solid temperature distribution and arbitrary variation of inlet gas temperature are allowed. The solution presented appears easier to apply in practice than those previously published and affords an example of the versatility of Fourier integrals and series. An application of the solution to the regeneration of Dow type‐B butylene dehydrogenation catalyst is described.

Measurement of the Ratio of the Principal Specific Heats of a Gas

THE constant, γ, relating the principal specific heats of a gas may be determined directly by a number of classical methods involving adiabatic expansions, the most reliable of which are the determination of the velocity of sound in the gas (Kundt's method) and the observation of adiabatic variations in gas pressure and temperature (Clément and Desormes, Lummer and Pringsheim's methods respectively).

Pressure and Temperature Cycles in the Reversing Layers of Cepheid Variables

The object of this paper is to draw attention to some interesting relations which exist between gas pressure and temperature variations in the reversing layers of Cepheids of different types. From these data, a pulsation of the reversing layer appears, which is out of phase with the pulsation of the photosphere.