Hydrostatic equilibrium

About: Hydrostatic equilibrium is a research topic. Over the lifetime, 2451 publications have been published within this topic receiving 62172 citations.

Modification of a variational objective analysis model for new equations for pressure gradient and vertical velocity in the lower troposphere and for spatial resolution and accuracy of satellite data

Abstract: Since late 1982 NASA has supported research to develop a numerical variational model for the diagnostic assimilation of conventional and space-based meteorological data. In order to analyze the model components, four variational models are defined dividing the problem naturally according to increasing complexity. The first of these variational models (MODEL I), the subject of this report, contains the two nonlinear horizontal momentum equations, the integrated continuity equation, and the hydrostatic equation. This report summarizes the results of research (1) to improve the way the large nonmeteorological parts of the pressure gradient force are partitioned between the two terms of the pressure gradient force terms of the horizontal momentum equations, (2) to generalize the integrated continuity equation to account for variable pressure thickness over elevated terrain, and (3) to introduce horizontal variation in the precision modulus weights for the observations.

Energy and force conditions of hydrostatic pressing of blanks from powder materials

Abstract: An examination is made of the hydrostatic pressing of metal powders. The total work done in this process is made up of six components. Their determination and methods of calculating them are described. Equations are proposed for calculating the work done in overcoming friction in the gland of the hydrostatic pressure vessel plunger. The equations allow for the variation of the coefficient of friction in the gland, which is a function of pressure in the vessel. Energy expenditure in hydrostatic pressing determined by calculation is in accord with experimental data. This shows that the equations proposed can be employed for choosing plant in the development of new technological processes for the production of parts from metal powders by hydrostatic pressing.

New Electromagnetic Force Sensor : Measuring the Density of Liquids

Abstract: We realized an electromagnetic force sensor for measuring the density of liquids by hydrostatic force exerted by liquids on a diver reference which characteristics are precisely known. The accuracy of the sensor is ∆m=0.3 mg and referring to the force is ∆F = 3µN .We will present in this paper the results of measuring the density of water-ethanol systems which was obtained by the accuracy of ∆ρ = 10 -4 g/cm 3 . The operating principle of this sensor is based on the fundamental laws of electromagnetism (Faraday-Lenz law). The density changes as a function of the molar fraction are monotonous in accordance with theory and the values of density measured with this device are in good agreement with the results found in the bibliography.

Liquid-to-gas differential pressure transmitter with small hydrostatic error

Abstract: A design is described for a device which transmits steady-state differential pressure from a liquid process to a gas differential pressure signal. By appropriate design, the hydrostatic error inherent in liquid-to-gas pressure transmission can be made negligibly small in relation to the accuracy of the differential pressure transducer. The instrument is a design modification of the “gas trap” method of pressure measurement for liquid-metal systems. The design described results in a simple, inexpensive, and easy to implement technique for liquid-metal differential pressure measurement, and, by appropriate design, with a negligible hydrostatic error. The design and implementation of such a system was undertaken with highly satisfactory results. Operational aspects of such a system are described. The design is applicable to a system where highly accurate steady-state differential pressure measurements are needed, while avoiding introduction of the process directly within the differential pressure transducer.

Modeling Pressure Fluctuation With Cross Flow in a Tight-Lattice Rod Bundle

Abstract: To explore the mechanism of differential pressure fluctuation inducing cross flow between subchannels in the tight-lattice rod bundle, an evaluation method is presented, which permits the prediction in detail of the unsteady differential pressure fluctuation behavior between subchannels. The instantaneous fluctuation of differential pressure between two subchannels in gas-liquid slug flow regime is deemed as a result of the intermittent nature of slug flow in each subchannel. The method is based on the detailed numerical simulation result of two-phase flow that pressure drop occurs mainly in the liquid slug region and it is, however, negligibly small in the bubble region. The instantaneous fluctuation of differential pressure between two subchannels is associated with pressure gradient in the liquid slug for each channel. In addition to a hydrostatic gradient, acceleration and frictional gradients are taken into account to predict pressure gradient in the liquid slug. This method used in conjunction with the numerical simulation code works satisfactorily to reproduce numerical simulation results for instantaneous fluctuation of differential pressure between two modeled subchannels. It is shown that the static head, acceleration, and frictional pressure drops in the liquid slug are main contributions to the fluctuation of differential pressure between subchannels.