scispace - formally typeset
Search or ask a question

Showing papers on "Pressure drop published in 1972"


Journal ArticleDOI
TL;DR: In this paper, the relationship between volume flow rate, pressure drop, and post extrusion swelling is analyzed in terms of extensional and simple shear components to calculate the relationships between volumes flow rate and pressure drop.
Abstract: Practical extrusion processes often involve geometrically complex dies. Such dies are usually tapered, or streamlined, to achieve maximum output rate under conditions of laminar flow. These converging flows may be analysed in terms of their extensional and simple shear components to calculate the relationships between volume flow rate, pressure drop, and post extrusion swelling. The analysis can also be extended to cover the free convergence as fluid flows from a reservior into a die. Comparisons between predicted and observed data for a series of coni-cylindrical dies suggest that using this approach the pressure drop/flow rate relationship can be predicted within ±20% and the swell ratio/flow rate relationship within ±10%. Similar treatments have been in use for the last three years in solving such complex flow problems as radial flow in injection moulding and two-dimensional annular convergence in blow moulding dies.

541 citations



Journal ArticleDOI
TL;DR: In this paper, a semi-empirical model was developed that can accurately predict pressure losses in a hexagonal array of fuel pins utilizing a wire-wrap spacer system, which is able to predict pressure drop to within ± 14 % over a wide range of geometries in the turbulent flow regime.

137 citations


Patent
15 Dec 1972
TL;DR: A simplified pressure regulator for fluids is proposed in this article, which has in-line construction having a tubular inline valve member that seats against a valve seat in a manner to provide balancing, the inline construction minimizing pressure drop.
Abstract: A simplified pressure regulator for fluids The regulator has in-line construction having a tubular in-line valve member that seats against a valve seat in a manner to provide balancing, the in-line construction minimizing pressure drop The body of the regulator comprises two relatively rotatable parts with in-line inlet and outlet connections thereby facilitating coupling to the regulator

125 citations


Journal ArticleDOI
TL;DR: In this paper, the results of measurements of the pressure drop over a range of Reynolds numbers Re = 6 × 102 − 2 × 105 in 25 test sections are communicated and compared with our results.

92 citations


Patent
15 Dec 1972
TL;DR: In this article, an improved valve, which may be used as a check valve, is designed to operate the closure mechanism at a preselected rate of fluid flow, in which the valve stem is urged away from the seat and against the flow by means of a spring.
Abstract: This disclosure describes an improved valve, which may be used as a check valve, in which the flow of fluid in the direction to close the valve, is designed to operate the closure mechanism at a preselected rate of fluid flow. There is a housing having an inlet at one end and a valve seat at the second end. There is an axial support means which carries a valve stem with a valve head at one end, adapted to seal against the seat. The valve stem is urged away from the seat and against the flow by means of a spring, until the valve head is seated against the end of the support means. The cross sectional area of the support means is less than the cross sectional area of the valve head. The valve head is of less diameter than the internal diameter of the housing which provides an annular space through which the fluid flows, and in which there is a pressure drop. Thus, the unit pressure on the leading, upstream face is higher than the unit pressure on the lower downstream face of the valve head. The upper pressure times the exposed area on the upper surface of the head provides a downward force which is balanced by the sum of the upward forces of the fluid pressure on the lower surface of the head and the spring force. As the fluid flow increases the pressure drop increases and at a selected value of fluid flow the downward force on the valve head will be sufficient to overcome the upward forces and the valve will move downward. This movement provides a space between the lower end of the support means and the upper surface of the valve head and exposes the entire upper surface of the valve head to the upstream pressure which now provides a greater downward force on the valve head, causing it to rapidly close, shutting off all fluid flow.

83 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present a theoretical study of the vibration and stability of a uniformly curved tube containing flowing fluid, where the assumption of the inextensibility of the tube is applied to derive the equation of motion.
Abstract: This paper presents a theoretical study of the vibration and stability of a uniformly curved tube containing flowing fluid. The assumption of the inextensibility of the tube is applied to derive the equation of motion. A solution for the natural frequency is obtained and numerical results are presented. The effects of flow velocity, fluid pressure, and the Coriolis force on the natural frequency are discussed. It is shown that when the flow velocity and fluid pressure exceed a certain value, the tube becomes subject to buckling‐type instability. Critical loads in terms of the flow velocity and fluid pressure are presented for fixed‐fixed, hinged‐hinged, and fixed‐hinged end conditions.

83 citations


Journal ArticleDOI
TL;DR: The steady flow of a viscous fluid through an elastic tube is determined theoretically and is in good agreement with experimental steady flow measurements on rubber tubes, on venous return to the heart, and on isolated cats' lungs.

75 citations



Journal ArticleDOI
TL;DR: In this paper, pressure drop and void fraction measurement were carried out for the two-phase cocurrent flow of gas and liquid in a helical coil of 12.5 mm i.d.

59 citations


Patent
30 Jun 1972
TL;DR: A logging-while-drilling tool is a tool that is adapted to be positioned within the drill string of a well drilling apparatus as discussed by the authors, which has a turbinelike, signal-generating valve which opens and closes at a defined rate to generate a pressure wave signal in the drilling fluid which is representative of a measured downhole condition.
Abstract: A logging-while-drilling tool which is adapted to be positioned within the drill string of a well drilling apparatus. The tool has a turbinelike, signal-generating valve which opens and closes at a defined rate to generate a pressure wave signal in the drilling fluid which is representative of a measured downhole condition. The tool includes spring means to normally bias the rotor away from the stator of the valve. The force constant of the spring means is greater than the pressure drop across the rotor at low flow rates but is less than the pressure drop at the flow rate at which the tool begins operation. This allows the tool to maintain a large gap between the rotor and stator prior to operation of the tool or during periods of nonoperation thereby alleviating the problem of plugging and/or jamming of the valve. During normal operation the net force holding the rotor down, i.e., the force due to hydraulic pressure drop minus the spring force, is relatively small so that the rotor will ride up over and free itself from material which may become lodged in the gap, thus alleviating jamming of the valve. Also, structural features of the rotor aid in alleviating plugging of the valve.

PatentDOI
TL;DR: A sampling and handling system for the exhaust of an automotive engine whereby emissions flowing through a throughduct are mixed, extracted through an isokinetic probe, and maintained heated until analysis of the sampled gases is completed.
Abstract: A sampling and handling system for the exhaust of an automotive engine whereby emissions flowing through a through-duct are mixed, extracted through an isokinetic probe, and maintained heated until analysis of the sampled gases is completed. A variable speed pump means is utilized to equalize the instantaneous pressure drop through the probe with the instantaneous pressure drop through the exhaust duct.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the effect of the eddy diffusivity of the gas flow containing the droplets from the relation between the distribution of velocity and that of shear stress in the gas stream.
Abstract: The experimental results are described on the transfer rate of liquid droplet onto the duct wall, the distributions of the droplet volumetric fraction, the droplet and gas velocities, and the pressure loss for a two-phase (Air-water) annular mist flow through a horizontal rectangular duct. The mean diameter of droplets was in a range from 27 to 40 microns in this experiment. The droplet transfer coefficient onto the wall derived from the experimental results indicates that it is affected by the droplet concentration as well as the gas velocity. Therefore, for investigating the mechanism of droplet transfer, the effect of the eddy diffusivity of the gas flow containing the droplets is discussed from the relation between the distribution of velocity and that of shear stress in the gas stream.

Journal ArticleDOI
TL;DR: In this article, the two-phase slug flow regime in horizontal cocurrent gas-liquid flow was studied for the case of the liquid phase containing small amounts of polyacrylamide, a drag-reducing long chain polymer.
Abstract: The two-phase slug flow regime in horizontal cocurrent gas-liquid flow was studied for the case of the liquid phase containing small amounts of polyacrylamide, a drag-reducing long chain polymer. The experimental work was performed in a 2.54 cm I.D. horizontal test section 10.7 m long. Results indicated that two-phase drag reduction was greater than in single phase flow at the same superficial liquid velocities. By the use of pressure drop results with and without polymer additive, and a knowledge of slug geometry, frequency, and velocity, it was possible to separate approximately the contribution to the pressure drop of liquid wall friction and slug intertial effects. In all cases, the acceleration term was important and is the major energy term at most flow conditions. The technique may be of general usefulness in determining accelerational effects in two phase flows. When drag reducing agents have been added to a horizontal slug flow, the pressure loss can be correlated successfully both by the Lockhart-Martinelli type of relationship or by a universal drag reduction curve of the type proposed by Virk.

Journal ArticleDOI
TL;DR: In this article, a theoretical method of predicting the pressure drop and hold up in stratified and wavy two-phase flow is presented, based on the flow model of Lockhart and Martinelli.

Journal ArticleDOI
TL;DR: In this paper, a method for the interpretation of pressure drop measurements with rough tubes, annuli and parallel plates is presented, where a parameter deduced describes the effect of roughness on a turbulent velocity profile.

Journal ArticleDOI
TL;DR: In this article, the authors considered viscous flow in a circular cylindrical tube containing an infinite line of viscous liquid drops equally spaced along the tube axis under the assumption that a surface tension, sufficiently large, holds the drops in a nearly spherical shape.
Abstract: Viscous flow in a circular cylindrical tube containing an infinite line of viscous liquid drops equally spaced along the tube axis is considered under the assumption that a surface tension, sufficiently large, holds the drops in a nearly spherical shape. Three cases are considered: (1) axial translation of the drops, (2) flow of the external fluid past a line of stationary drops, and (3) flow of external fluid and liquid drops under an imposed pressure gradient. Both fluids are taken to be Newtonian and incompressible, and the linearized equations of creeping flow are used. The results show that both drag and pressure drop per sphere increase as the spacing increases at fixed radius and also increase as the radius of the drop increases. The presence of the internal motion reduces the drag and pressure gradients in all cases compared to rigid spheres, particularly for drops approaching the size of the tube.

Patent
27 Nov 1972
TL;DR: A bonded activated carbon filter and a method for making the same is described in this article, which is a self-contained disposable filter having voids in sufficient amount to provide a pressure drop of about 0 to 0.5 inches of water at a face velocity of up to approximately 450 feet per minute.
Abstract: A bonded activated carbon filter and a method for making the same are disclosed. The filter contains activated carbon and a thermosetting or thermoplastic resin binder, and is a selfcontained disposable filter having voids in sufficient amount to provide a pressure drop of about 0 to 0.5 inches of water at a face velocity of up to approximately 450 feet per minute. The method includes mixing the dry ingredients and sufficient water, charging to a mold, applying sufficient pressure, discharging the green mold piece and curing the resulting filter. By the use of granular activated carbon a larger filled face area/void ratio may be provided for certain applications since the granular material provides some permeability through the filled face area while the voids permit control of the pressure drop characteristics of the filter.

Patent
25 Sep 1972
TL;DR: In this paper, a control valve has a stator which imparts a swirl to the flow of fluid and a rotor which is rotated under the swirl of fluid in various ways.
Abstract: The control valve has a stator which imparts a swirl to the flow of fluid and a rotor which is rotated under the swirl of fluid. Energy is absorbed from the rotor in various ways. In one instance, the rotation of the rotor is subjected to a drag force which is induced in opposition to the force of rotation in order to control the pressure drop in the flow. In another instance, the rotation of the rotor is used to store electrical energy which can be used for other purposes throughout the process system.


Journal ArticleDOI
11 Sep 1972-Nature
TL;DR: The addition of small amounts of certain materials to fluids undergoing turbulent flow causes a reduction on pressure drop called drag reduction as mentioned in this paper, which has been shown to be beneficial in many applications.
Abstract: THE addition of small amounts of certain materials to fluids undergoing turbulent flow causes a reduction on pressure drop called drag reduction. Polymer solutions, soap solutions and solid suspensions in liquids and gases have all demonstrated this phenomenon1.


Patent
05 May 1972
TL;DR: In this article, a pressure compensated spool type directional control valve characterized in that it has a compensating piston which senses the pressure drop across a metering orifice whose flow area is determined by the position of the spool in the valve housing.
Abstract: A pressure compensated spool type directional control valve characterized in that it has a compensating piston which senses the pressure drop across a metering orifice whose flow area is determined by the position of the spool in the valve housing and which is operative to divert excess flow to the reservoir when the pressure drop across the metering orifice exceeds a predetermined value, said compensating piston being so operative in conjunction with the operation of any one of the spools of a plural spool directional control valve. The compensating piston may also be operated as an unloading valve to bypass pump output to the reservoir when the spool or spools of the directional control valve are in neutral position, or as a relief valve by employment of a pilot relief valve member in association with the side of the compensating piston which is exposed to pressure downstream of the metering orifice. Another characterizing feature of the pressure compensated directional control valve herein is that each spool has a secondary compensating piston therein which decreases the pressure drop flow forces at the spool metering orifice. In a two-spool directional control valve the compensating piston adjusts to the lower load demand when both spools are simultaneously shifted to an operating position. In one form of two-spool directional control valve having a pressure compensating piston as aforesaid, check valves are provided to make adjustment to the higher load when both spools are simultaneously shifted to an operating position.

Proceedings ArticleDOI
01 Jan 1972
TL;DR: In this paper, a modified form of the non-Newtonian Darcy equation has been developed to predict the viscous and elastic pressure drop vs. flow rate relationships for flow of the elastic CMC solutions in beds of different geometry.
Abstract: The present investigation shows how viscoelastic fluids behave while flowing through unconsolidated porous media. The geometry of the porous media significantly affects elastic responses. The critical shear rate at which elastic effects are first noticed is significantly lower for the irregular sand and binary mixtures of glass beads than for regular glass spheres. Further, the critical shear rates for regular packing are independent of the CMC concentration. A narrow range of concentration of CMC and carbopol exists where elastic effects are first noticed. Below this concentration range, viscous forces control; while, above, elastic effects occur. A modified form of the non-Newtonian Darcy equation has been developed to predict the viscous and elastic pressure drop vs. flow rate relationships for flow of the elastic CMC solutions in beds of different geometry. The equation fits the data of this study with a maximum deviation of 11%. (13 refs.)

Journal ArticleDOI
TL;DR: In this article, a χ2 minimisation procedure on data obtained for two-phase liquid flow in a helical coil was used to establish empirical exponents appearing in these correlations.

Journal ArticleDOI
TL;DR: In this paper, the variation of sessile drop height with drop size has been calculated and is given in graphical form for a very wide range of drop size and of contact angle, which are then used to derive correction factors so that the surface tension and the spreading coefficient may be obtained from equations which would normally apply with the limiting drop height.
Abstract: The height of a sessile drop first increases as the drop size increases and then diminishes to a limiting value for very large drops. The variation of sessile drop height with drop size has been calculated and is given in graphical form for a very wide range of drop size and of contact angle. These data are then used to derive correction factors so that the surface tension and the spreading coefficient may be obtained from equations which would normally apply with the limiting drop height. A comparison is made of these data with some empirical equations, developed by earlier workers, to express the drop height as a function of its size. It is shown that these equations apply over limited ranges of size only. The phenomenon of a sessile drop possessing some maximum height is shown to be a consequence of the capillary pressure at the apex changing with drop diameter in a different way from that at the base of the drop.

Patent
Lorne W. Nelson1
27 Sep 1972
TL;DR: A filter condition responsive apparatus for a range or stove vent system containing a first filter for filtering grease and a second series connected filter for the removal of odors is described in this article.
Abstract: A filter condition responsive apparatus for a range or stove vent system containing a first filter for filtering grease and a second series connected filter for the removal of odors. A first pressure responsive device responds to the pressure drop across the grease filter to provide an output indicative of the collection of grease on the filter. A second pressure responsive device responds to the pressure drop across the second filter to provide an output indicative of the flow of air through the filter. The output of the two devices are connected to provide an indication of the condition of the grease filter independent of any change in air flow.

Journal ArticleDOI
TL;DR: In this article, the simultaneous flow of the superfluid and normal components of liquid He II through a capillary is studied, and the manner in which the two fluids are forced to flow with independently adjustable velocities is described.

Journal ArticleDOI
TL;DR: In this article, the effect of solids loading ratio, particle size, and gas Reynolds number on the pressure drop and flow characteristics of a dilute gas-solid suspension in turbulent pipe flow has been studied experimentally in both vertical and horizontal test sections.
Abstract: The effect of solids loading ratio, particle size, and gas Reynolds number on the pressure drop and flow characteristics of a dilute gas-solid suspension in turbulent pipe flow has been studied experimentally in both vertical and horizontal test sections. Glass beads of 10 to 60μ diameter were used at air Reynolds numbers of 10,000 to 25,000 and solids loading ratios of up to 2.5 Drag reduction was observed in the vertical test section for all of the particles studied, with the 30μ particles yielding a maximum drag reduction of about 75% at a loading ratio of 1.5. In the horizontal test section, drag reduction was observed only with the smallest sized particles, indicating a gravity effect. An explanation of these results based on the particles interacting with the turbulent structure of the gas near the wall has been proposed.

Patent
02 Nov 1972
TL;DR: In this article, a servo valve actuated by the buildup of pressure in the pump outlet caused by normal parasitic losses in a downstream hydraulic flow circuit is described. But the authors do not specify a suitable orifice for the return of the servo to the pump.
Abstract: The pressure acting on a pressure loaded cheek plate in a pump is selectively vented by a servo valve actuated by the buildup of pressure in the pump outlet caused by normal parasitic losses in a downstream hydraulic flow circuit. Since it may be desirable to actuate the servo valve by the pressure drop across an orifice in the outlet line or by a suitable orifice in the pump return to pump, both embodiments are disclosed as exemplary means for achieving the premises of this design.