Showing papers in "Experimental Thermal and Fluid Science in 1990"

TL;DR: In this paper, the authors investigated the heat transfer and pressure drop characteristics of a circular tube fitted with regularly spaced twisted-tape elements connected by thin circular rods and found that the regularly spaced tape elements performed significantly better than full-length twisted tapes at high Reynolds numbers, high twists, and small spacings.

TL;DR: In this article, a conditional sampling technique was applied in a study of the boundary layer flow undergoing transition from laminar to turbulent flow and the results showed that the transition process is characterized by two distinctive stages; the flow structures and energy transports are very different in these two stages.

TL;DR: In this article, the most important geometric parameter influencing the heat transfer from pin fin arrays is the ratio of the fin diameter to the center-to-center spacing, and the experimental results indicate that a pin fin array performs better than a plate fin array under the same conditions.

TL;DR: In this article, an experimental method and apparatus were developed to measure local heat transfer distributions on moving and stationary plates, where surface motion is either in or opposite to the flow direction.

TL;DR: In this paper, the authors investigated thermal instabilities in forced convection boiling in a vertical single channel system, with Freon-11 as the working fluid, and they used finite difference techniques to determine the wall conditions, fluid properties and flow conditions at any point along the test section.

TL;DR: In this paper, it is argued that the most important test of the understanding of any experiment is whether or not the results are consistent with the equations and boundary conditions believed to govern the flow, and if they are not, then either the measurements are incorrect, the equations or boundary conditions are wrong, or the experiment performed was not the one believed to have been done.

TL;DR: In this paper, the axial momentum equation for flow in a tube containing regularly spaced twisted-tape elements has been integrated to yield a correlation for friction factor that reflects the influences of secondary flows and wall shear.

TL;DR: The topics treated are thermocouple theory, high-temperature thermocouples, surface-tem temperature measurements, heat flux transducers, the definition of h, planar laser-induced fluorescence, and liquid crystals in heat transfer research.

TL;DR: An overview of the last decade of development in experimental techniques and methods used to study multiphase flow is provided and the application of these techniques is illustrated for the measurement of, for example, phase velocity, temperature, flow regimes, and void fraction.

TL;DR: In this article, the two-phase frictional pressure drop and vapor volume fraction in the vertical boiling and adiabatic flow of the refrigerant, R11, have been simultaneously measured by a liquid balancing column and differential magnetic reluctance pressure transducers.

TL;DR: In this article, experiments were performed on a 204 mm diameter water-cooled cyclone to measure the pressure drop and heat transfer in different sections of the cyclone with and without suspended particles.

TL;DR: In this article, the effects of geometry of the test section, such as aspect ration, hydraulic equivalent diameter of a cross section, and inclination angle of the channel, on the two-phase frictional pressure drop in a rectangular channel were investigated experimentally.

TL;DR: In this paper, a correlation for minimum film boiling temperature on solid surfaces with various thermal physical properties in various liquids is presented based on the experimental results, and the lower limits of heterogeneous spontaneous nucleation temperatures measured on the same cylinder in liquid nitrogen at various pressures agreed well with each other.

TL;DR: In this paper, the effects of flow channel size, presence of the unheated fuel rod bundle, and perforated plate thickness on countercurrent flow behavior were observed in large channel geometrics.

TL;DR: The influence of sound on the type of experimental methods used in flow and heat transfer test rigs is discussed in this article, where the authors show that sound levels between 70 and 95 dB (with corresponding ratios of the velocity due to sound to the freestream velocity of between ∼ 0.0001 and ∼ 0.002) generated by the flow can alter both the flow and the heat transfer characteristics in a manner not immediately obvious to the experimenter.

TL;DR: In this paper, the influence of surface oxidation, liquid subcooling and surface roughness on pool boiling from a 1.27-cm copper sphere was reported, which was specially designed to minimize support interference with vapor formation and removal.

TL;DR: Brodkey et al. as discussed by the authors presented a physical model of turbulent flows that can be used as a basis for modeling realistic base for boundary layer flow that would consist of the entire instantaneous vector velocity field in all of space for a specific period of time.

TL;DR: In this paper, the effects of break orientation on thermal-hydraulic responses were investigated at the ROSA-IV Large Scale Test Facility (LSTF) to investigate the effect of small-break loss-of-coolant accident (SBLOCA).

TL;DR: In this article, a sort of "siphon condensation" occurs in the U-tubes of steam generators when primary-side mass inventory reaches roughly 64% of the initial value.

TL;DR: In this article, the results of simulations are presented that quantify the error in the estimated heat transfer coefficient due to specific common mismatches between the model and the experiment and lead to the recommendation that singl-blow facilities be calibrated with tests on a core of known performance to demonstrate the appropriateness of the model as well as the accuracy of the measurements.

TL;DR: In this paper, nucleate pool boiling tests were performed on a number of GEWA-T deformed low fin surface copper tubes in saturated R-113, and the boiling curves exhibited the hysteresis effect commonly observed with liquids of high wettability.

TL;DR: In this paper, the authors measured the variation of heat transfer coefficient around the periphery of a tube with the aim of clarifying the nucleate boiling mechanism on the outside of a horizontal tube and found that at very low velocities there is a marked change in the variation, with the maximum coefficient occurring at a point about 70° from the base.

TL;DR: In this paper, heat transfer during forced convective subcooled boiling of three binary mixtures was experimentally studied in a boiling loop at different liquid velocities, degress of subcooling, and concentrations of the mixture.

TL;DR: In this paper, an experimental technique is described for obtaining time-resolved heat flux measurements with high-frequency response (up to 100 kHz) in a steady-flow ambient-temperature facility.

TL;DR: The theory of thermopiles from multipairs of thermocouples for precise measurement of temperature difference ΔT was derived, and a calibration and signal conversion method using the theory was developed in the present study.

TL;DR: The image processing system described considerably reduces the total measuring time, eliminates subjective observer error in sizing and counting spray drops, and has proved to be substantially efficient.

TL;DR: In this paper, a thermally excited jet was used to study the surface tension of a jet of water issuing into the air, and the growth rate of the jet was found to be consistent with Rayleigh's linear stability theory.

TL;DR: In this paper, the authors used a nonlinear κ-ϵ model to simulate the flow numerically and found that the reattachment length of the present problem was considerably shorter than that of two-dimensional backward-facing step flow.

TL;DR: In this paper, a thermohydrodynamic approach to the analysis of film boiling crisis is suggested, and a generalization of data on ΔT min is made within that framework, which can also be used for Leidenfrost temperature evaluation.

TL;DR: In this article, the use of micro-sensors for heat transfer and fluid flow measurements is discussed, both as low-cost substitutes for existing transducers and as specialty devices for high spatial resolution and fast response needs.