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Total pressure
About: Total pressure is a research topic. Over the lifetime, 5199 publications have been published within this topic receiving 66658 citations.
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TL;DR: In this paper, a theoretical and experimental study has been made on the dynamic characteristics of a centrifugal pump subject to sinusoidal changes in rotational speed, and the deviation of unsteady characteristics from quasi-steady ones is evident.
Abstract: A theoretical and experimental study has been made on the dynamic characteristics of a centrifugal pump subject to sinusoidal changes in rotational speed. Time-dependent rotational speed, flow-rate, and total pressure rise are measured for a variety of amplitude and frequency of the fluctuating rotational speed. Measured flow-rate as well as total pressure rise is compared with the quasi-steady ones. Unsteady flow analysis is made for a two-dimensional circular cascade by use of the singularity method. The calculated frequency characteristics are compared with the corresponding experimental ones. The deviation of unsteady characteristics from quasi-steady ones is evident, and the numerical results agree qualitatively with the measured ones. It was found that with the increased frequency of rotational speed fluctuations the dynamic characteristics deviate remarkably from quasi-steady ones. Moreover, a criterion for the assumption of quasi-steady change is presented.
32 citations
TL;DR: In this article, the deformation resistance of porous metal, maximum specific pressure, and other rolling parameters were analyzed and full and simplified formulas were obtained for determining the total pressure during the rolling of metal powders.
Abstract: As a result of an analytical examination of specific pressure distribution during the rolling of metal powders, formulas are derived for determining specific pressure in the lag and forward-slip zones. A relationship is found between the deformation resistance of porous metal, maximum specific pressure, and other rolling parameters. Full and simplified formulas are obtained for determining the total pressure during the rolling of metal powders.
31 citations
TL;DR: In this article, a simple method is described for measuring material erosion by reaction with water vapor under high-speed flow conditions, with H2O partial pressures, velocities, temperatures, and erosion rates representative of those experienced in gas turbine engines.
Abstract: A simple method is described for measuring material erosion by reaction with water vapor under high-speed flow conditions, with H2O partial pressures, velocities, temperatures, and erosion rates representative of those experienced in gas turbine engines. A water vapor jet is formed by the feeding water at a controlled rate into a capillary inside a tube furnace, where the large expansion of vaporization within the confines of the capillary accelerates the jet. With modest flow rates of liquid water, steam jets with temperatures up to ∼1400°C and velocities in the range 100–300 m/s have been achieved. The partial pressure of water vapor in the 100% steam jet is the same as in an industrial turbine operating at 10 atm total pressure with 10% water vapor. In preliminary experiments with SiC, erosion rates of the order of 1 μm/h have been observed.
31 citations
TL;DR: In this paper, a macro-micro approach to mixed lubrication has been developed, where the relation between the average contact pressure and the average gap for a typical rough contact patch is first determined numerically in micro scale.
Abstract: Mixed lubrication is a key to bring the performance analysis to the failure analysis in most tribological components. A macro-micro approach to mixed lubrication has been developed in the present model. The relation between the average contact pressure and the average gap for a typical rough contact patch is first determined numerically in micro scale. Using this relation, the average gap, average oil-film pressure, and average contact pressure in a mixed-lubricated elastohydrodynamic contact can be solved simultaneously in macro scale by treating the contact to be smooth. The total pressure is assumed a superposition of average asperity contact pressure and lubricant pressure. The new approach is simple, efficient and robust, and covers entire range of the load ratio, from unity (dry contact) to zero (full-film EHL). In addition, it can be used for a wide range of operating conditions and on a much larger contact area with a much less computing time than deterministic simulation of mixed lubrication. Imp...
31 citations
TL;DR: In this paper, the results for two planar converging-diverging nozzles in the adapted regime and at different inlet conditions, from highly non-ideal to dilute gas state, are reported.
Abstract: Supersonic expansions of a molecularly complex vapor occurring within the non-ideal thermodynamic region in the close proximity of liquid-vapor saturation curve were characterized experimentally for the first time. Results for two planar converging–diverging nozzles in the adapted regime and at different inlet conditions, from highly non-ideal to dilute gas state, are reported. Measurements of upstream total pressure and temperature are performed in the plenum ahead of the nozzle, while static pressure and supersonic Mach number measurements are carried out along the nozzle centerline. The investigated expansions are of interest for both fundamental research on non-ideal compressible flows and industrial applications, especially in the energy field. Siloxane MDM (octamethyltrisiloxane, $$\text {C}_8\text {H}_{24}\text {O}_2\text {Si}_3$$
), a high molecular complexity organic compound, is used. Local pressure ratio $$P/P_\mathrm{T}$$
and Mach number M measurements display a dependence on the inlet total state, a typical non-ideal feature different from dilute gas conditions.
31 citations