Buoyancy-Driven Exchange Flow Through Small Openings in Horizontal Partitions

1988 ◽  
Vol 110 (4a) ◽  
pp. 885-893 ◽  
Author(s):  
M. Epstein
Keyword(s):  
Flow Rate ◽  
Countercurrent Flow ◽  
Exchange Flow ◽  
Flow Measurements ◽  
Rate Versus ◽  
Single Opening ◽  
Flow Through ◽  
Horizontal Partition ◽  
Flow Configurations ◽  
Universal Correlation

This paper describes an experimental study of the phenomenon of buoyancy-driven exchange (countercurrent) flow through openings in a horizontal partition. A density-driven exchange flow was obtained by using brine above the partition and fresh water below the partition. In the first part of the study, flow measurements were made with a single opening, for opening ratios L/D in the range 0.01 to 10.0, where L and D are the length of the opening (in the direction normal to the partition) and the diameter of the opening, respectively. Four different flow regimes are identified as L/D is increased through this range. As a result of the competition between two of these regimes, the exchange flow rate versus L/D relation exhibits a peak. The exchange flow rate was found, for all practical purposes, to be independent of viscosity, enabling a universal correlation between Froude number (dimensionless exchange flow rate) and L/D. The second part of the study was an experimental investigation of the same phenomenon, but with two openings in the horizontal partition. Two openings were observed to give rise to three different flow configurations involving both one-way and countercurrent flows within the openings.

Combined Natural Convection and Forced Flow Through Small Openings in a Horizontal Partition, With Special Reference to Flows in Multicompartment Enclosures

1989 ◽  
Vol 111 (4) ◽  
pp. 980-987 ◽  
Author(s):  
M. Epstein ◽  
M. A. Kenton
Keyword(s):  
Direct Application ◽  
Forced Flow ◽  
Theoretical Treatment ◽  
Exchange Flow ◽  
Exchange Flows ◽  
Toxic Gases ◽  
Buoyancy Driven Flows ◽  
Single Opening ◽  
Flow Through ◽  
Horizontal Partition

Estimates of the magnitude of buoyancy-driven exchange flows through openings in partitions that separate compartments are needed to assess the movement of toxic gases and smoke through buildings. An experiment using water and brine as a substitute for a light gas moving in a dense gas was designed to measure combined forced and buoyancy-driven exchange flow through a single opening in a horizontal partition. No theoretical treatment exists for this configuration. The same apparatus was used to determine the magnitude of the forced flow required to purge the opening of the oppositely directed buoyant component (i.e., the “flooding” limit). Finally, combined forced and buoyancy-driven flows in a multicompartment enclosure were measured. It has been demonstrated that the combined forced and buoyancy-generated flows in the multicompartment structure can be predicted by a direct application of the results of the study of exchange flow through a single opening.

scholarly journals Aeration of the premises of the dairy cows keeping in the light weight design in the warm period of the year

2020 ◽  
pp. 45-47
Author(s):  
Darya Viktorovna Abramkina
Keyword(s):  
Dairy Cows ◽  
Flow Rate ◽  
Significant Contribution ◽  
Air Flow ◽  
Warm Period ◽  
Light Weight ◽  
Exchange Flow ◽  
Weight Design ◽  
Flow Through ◽  
Air Exchange

The purpose of the article is to conduct multivariate calculations of aeration in a building at dairy cows keeping in order to identify the most effective way of ensuring normal air exchange in the stall house. According to the results of studies, it was found out that the supply air flow through the external gate makes a significant contribution to the overall air exchange of the stall house. Keywords: aeration; cowshed; ventilation; air exchange; flow rate.

scholarly journals Flow Measurements Using a Sluice Gate; Analysis of Applicability

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 819
Author(s):  
Elżbieta Kubrak ◽  
Janusz Kubrak ◽  
Adam Kiczko ◽  
Michał Kubrak
Keyword(s):  
Water Flow ◽  
Cross Section ◽  
Discharge Capacity ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Sluice Gate ◽  
Flow Measurements ◽  
Discharge Coefficients ◽  
Flow Through ◽  
Submerged Conditions

This study analyzes the possibilities of using an irrigation sluice gate in submerged conditions to measure water flow rate. Hydraulic experiments on sluice gate discharge capacity were performed on a model made on a 1:2 scale. Measurements were taken for the submerged flow of the sluice gate. Nomograms and relationships for discharge coefficients of the analyzed sluice gate were developed. The possibility of using the existing nomogram for discharge capacity of the submerged sluice gate to determine the discharge capacity of the modeled gate was also investigated. The effect of narrowing of the sluice gate cross-section resulting from different mounting techniques on its capacity was explained. The analyses confirmed the possibility of using the formulas for the submerged sluice gate to estimate the flow through the irrigation sluice gate.

Unsteady Buoyancy Exchange Flow Through a Horizontal Partition

1995 ◽  
Vol 117 (2) ◽  
pp. 515-520 ◽  
Author(s):  
M. Singhal ◽  
R. Kumar
Keyword(s):  
Exchange Flow ◽  
Flow Through ◽  
Horizontal Partition

Unsteady two-layer hydraulic exchange flows with friction

2009 ◽  
Vol 633 ◽  
pp. 99-114 ◽  
Author(s):  
S. S. LI ◽  
G. A. LAWRENCE
Keyword(s):  
Exchange Rate ◽  
Flow Rate ◽  
Laboratory Experiments ◽  
Time Dependent ◽  
Forced Flow ◽  
Exchange Flow ◽  
Interface Position ◽  
Exchange Flows ◽  
Sea Straits ◽  
Flow Through

Two-layer exchange flow through a contraction with both friction and barotropic forcing is modelled in terms of three parameters reflecting the friction and the strength and period of the barotropic forcing. In the appropriate limits, the results for steady flow with and without friction, and inviscid barotropically forced flow are recovered. The predicted time-dependent interface position compares well with laboratory experiments, improving on the inviscid formulation. The concurrent effects of friction and barotropic forcing on average exchange flow rate are determined. When friction is weak barotropic forcing increases the exchange rate. However, when friction is high, tidal forcing can result in a reduced exchange rate, a phenomena that we call tidal inhibition. When friction is weak maximal exchange occurs throughout the tidal cycle, but as friction is increased submaximal flow develops for longer and longer periods. As friction is increased even further the flow becomes hydraulically uncontrolled. The parameter range for major sea straits includes tidally enhanced and tidally inhibited flows, as well as maximal, submaximal and uncontrolled flows.

Stabilization of the Speed of the Hydraulic Motor Through Throttle Compensation for Volume Losses

2020 ◽  
Vol 26 (3) ◽  
pp. 126-130
Author(s):  
Krasimir Kalev
Keyword(s):  
Flow Rate ◽  
Hydraulic Drive ◽  
Pressure Change ◽  
Operating Conditions ◽  
Drive System ◽  
Inlet Pressure ◽  
Schematic Diagram ◽  
Hydraulic Characteristics ◽  
Hydraulic Motor ◽  
Flow Through

AbstractA schematic diagram of a hydraulic drive system is provided to stabilize the speed of the working body by compensating for volumetric losses in the hydraulic motor. The diagram shows the inclusion of an originally developed self-adjusting choke whose flow rate in the inlet pressure change range tends to reverse - with increasing pressure the flow through it decreases. Dependent on the hydraulic characteristics of the hydraulic motor and the specific operating conditions.

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