Showing papers in "Journal of Fluids Engineering-transactions of The Asme in 1985"
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TL;DR: In this paper, an experimental investigation of the air flow through various axisymmetric intake ports of a reciprocating engine is reported, where detailed velocity field measurements obtained by laser Doppler anemometry and for steady and various unsteady flow conditions are presented together with valve discharge coefficients from steady flow tests.
Abstract: An experimental investigation of the air flow through various axisymmetric intake ports of a reciprocating engine is reported. Detailed velocity field measurements obtained by laser Doppler anemometry and for steady and various unsteady flow conditions are presented together with valve discharge coefficients from steady flow tests. The results showed that the flow at the valve exit exhibited four regimes with a 45 seat angle compared to three in the case of a 60 valve. The overall behavior of the 45 valve, however, was found to be generally better. Rounding of the edges of the 45 valve reduced the number of flow regimes to two with marked improvements on discharge coefficient. The flow angle at the valve exit depended less on the flow regime and more on the cylinder confinement, in the absence of which the transition from one regime to another was delayed. The mean flow pattern at the valve exit was found to be insensitive to flow unsteadiness, piston confinement and valve operation and thus could be predicted with reasonable accuracy from steady flow tests. The in-cyclinder flow characteristics were also insensitive to valve operation, but strongly depended on piston interaction, flow unsteadiness and residual effects from the previousmore » cycle.« less
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TL;DR: In this paper, a program standart de calcul de la couche limite turbulente is used to model the reduction of the frottement superficiel par l'injection of microbulls.
Abstract: Tentative de modelisation du phenomene de reduction du frottement superficiel par l'injection de microbulles. On utilise un programme standart de calcul de la couche limite turbulente. Etudes parametriques de la localisation des bulles de la couche limite, de la concentration maximale et du modele de viscosite du melange
TL;DR: The authors propose de two mecanismes explicatifs de l'interaction observee entre la pression transitoire and le deplacement de la conduite.
Abstract: Etude experimentale de la modification de la pression due au deplacement du coude du fait des contraintes axiales dans la conduite et de la pression du liquide, lorsque le support du coude n'est pas fixe. On propose deux mecanismes explicatifs de l'interaction observee entre la pression transitoire et le deplacement de la conduite
TL;DR: In this article, a numerical technique was developed to investigate the performance of automotive lifting surfaces in close proximity to ground, based on the Vortex Lattice Method and including freely deforming wake elements.
Abstract: A numerical technique was developed to investigate the performance of automotive lifting surfaces in close proximity to ground. The model is based on the Vortex Lattice Method and includes freely-deforming wake elements. The ground effect was simulated by reflection and both steady and unsteady pressures and loads on various wing planforms were considered. Calculated results are presented for wings having both positive and negative incidences, with and without ground effect. Also the transient lift of a wing in a plunging motion was analyzed in ground proximity and at a negative angle of attack. Finally the periodic lift fluctuations on the front winglet of a racing car, due to its suspension oscillations, were calculated and found to exceed approximately twice the steady-state value.
TL;DR: In this article, the authors used LIDV measurements in an IC engine motored at 1200 rpm to characterize the bulk velocity in individual cycles and found that the relative cyclic fluctuation of the bulk velocities was as large as 200 percent.
Abstract: LDV measurements have been made in an IC engine motored at 1200 rpm. The data rates were sufficiently high to allow the bulk velocity to be characterized in individual cycles. The relative cyclic fluctuation of the bulk velocity was found to be as large as 200 percent. The turbulence intensity was calculated using both the velocity fluctuation with respect to the ensemble average velocity and the velocity fluctuation with respect to the cycle resolved bulk velocity. The former includes both the cyclic fluctuation of the bulk velocity and the turbulence, and therefore gave estimates of the ensemble averaged turbulence intensity which were from 50 to 100 percent greater than that obtained using the in-cycle fluctuation with respect to the bulk velocity. The relative cyclic fluctuation of the time averaged turbulence intensity, calculated over a 64-degree interval in each cycle, was found to be small, i.e., less than 20 percent. The high data rates also made it possible to determine the ensemble averaged temporal autocorrelation function from which the spectral energy distribution and the integral time scale were calculated.
TL;DR: In this article, an analytical method has been developed to determine the performance of pumps operating under two-phase flow conditions, and the numerical results for head degradations and torques obtained with the model favorably compared with the air/water two phase flow test data of Babcock and Wilcox (1/3 scale) and Creare (1 /20 scale) pumps.
Abstract: During operational transients or a hypothetical LOCA (loss of coolant accident) condition, the recirculating coolant of PWR (pressurized water reactor) may flash into steam due to a loss of line pressure. Under such two-phase flow conditions, it is well known that the recirculation pump becomes unable to generate the same head as that of the single-phase flow case. Similar situations also exist in oil well submersible pumps where a fair amount of gas is contained in oil. Based on the one dimensional control volume method, an analytical method has been developed to determine the performance of pumps operating under two-phase flow conditions. The analytical method has incorporated pump geometry, void fraction, flow slippage and flow regime into the basic formula, but neglected the compressibility and condensation effects. During the course of model development, it has been found that the head degradation is mainly caused by higher acceleration on liquid phase and deceleration on gas phase than in the case of single-phase flows. The numerical results for head degradations and torques obtained with the model favorably compared with the air/water two-phase flow test data of Babcock and Wilcox (1/3 scale) and Creare (1/20 scale) pumps.
TL;DR: In this paper, the steady laminar flow in a parallel plate channel bounded below by a porous layer of finite thickness and above by a rigid impermeable plate moving with a uniform velocity is studied.
Abstract: The steady laminar flow in a parallel plate channel bounded below by a porous layer of finite thickness and above by a rigid impermeable plate moving with a uniform velocity is studied. The two cases, the porous medium bounded below (i) by a static fluid and (ii) by a rigid impermeable stationary wall, are considered separately. It is shown that when the thickness of the porous layer tends to infinity our modified slip condition tends to the slip condition postulated by G. S. Beavers and D. D. Joseph. Methods to estimate the viscosity factor lambda and relative permeability are discussed. The effect of the finite thickness of the porous medium is significant only for large values of lambda and small values of the porous parameter.
TL;DR: In this article, an analytical investigation of the unsteady potential flow in a narrow annular passage formed by a motionless rigid duct and an oscillating rigid center-body, both of axially variable cross section, was performed to determine the fluid-dynamic forces exerted on the center body.
Abstract: This paper presents an analytical investigation of the unsteady potential flow in a narrow annular passage formed by a motionless rigid duct and an oscillating rigid center-body, both of axially variable cross section, in order to determine the fluid-dynamic forces exerted on the center-body. Based on this theory, a first-approximation solution as well as a more accurate solution are derived for the unsteady incompressible fluid flow. The stability of the center-body is investigated, in terms of the aerodynamic (or hydrodynamic) coefficients of damping, stiffness and inertia (virtual mass), as determined by this theory. The influence of various system parameters on stability is discussed.
TL;DR: The rotor force test facility at the Rotor Force Test Facility (RFTF) was designed and constructed in order to measure these kinds of forces acting on a centrifugal pump impeller when the latter is made to whirl in a slightly eccentric circular orbit.
Abstract: The present work is an experimental investigation of the possible forces of fluid dynamic origin that can act on a turbomachine rotor particularly when it is situated off its normal center position. An experimental facility, the Rotor Force Test Facility, has been designed and contructed in order to measure these kinds of forces acting on a centrifugal pump impeller when the latter is made to whirl in a slightly eccentric circular orbit. The scope of the present experimental work consists of measuring quasi-steady forces on the impeller as it whirls slowly about the axis of the pump rotation. These forces are due to interaction between the impeller and volute; they are decomposed into force components relative to the geometric center of the volute and to those proportional to displacent from this center. These latter are interpreted as stiffness matrices. Such matrices were obtained for two different volutes and both were found to be the sum of a diagonal and a skewsymmetric matrix. It can be shown that a stiffness matrix of this type can lead to dynamic instability of impeller shaft system in certain circumstances. This new experimental finding may explain some operational problems of "high-speed" hydraulic machinery. Comparison is made with various existing theoretical and experimental results.
TL;DR: The numerous potentially significant scaling parameters are discussed in detail and laboratory test data illustrating the effects of the important scaled parameters are presented.
Abstract: This paper presents an overview of the current state-of-the-art in scale modeling of liquefied natural gas sloshing in ship tanks. The numerous potentially significant scaling parameters are discussed in detail and laboratory test data illustratingthe effects of the important scaling parameters are presented. In view of current knowledge, an indication of appropriate scaling criteria is presented and recommendations for additional research efforts are outlined.
TL;DR: In this article, current computational methods for analyzing flows in turbomachinery and other related internal propulsion components are divided into two classes: inviscid methods and viscous methods, respectively.
Abstract: Current computational methods for analyzing flows in turbomachinery and other related internal propulsion components are presented The methods are divided into two classes The inviscid methods deal specifically with turbomachinery applications Viscous methods, deal with generalized duct flows as well as flows in turbomachinery passages Inviscid methods are categorized into the potential, stream function, and Euler approaches Viscous methods are treated in terms of parabolic, partially parabolic, and elliptic procedures Various grids used in association with these procedures are also discussed
TL;DR: In this paper, the authors propose a theory for the coefficient de la contraction a l'orifice en fonction du rapport de la surface en aval for des champs d'ecoulement symetriques and bidimensionnels.
Abstract: Developpement d'une theorie pour le calcul du coefficient de la contraction a l'orifice en fonction du rapport de la surface en aval pour des champs d'ecoulement symetriques et bidimensionnels. Cette theorie s'applique a un ecoulement permanent newtonien, incompressible, non visqueux a la limite mais les principes peuvent etre etendus a des conditions plus generales. Comparaisons avec les donnees experimentales
TL;DR: In this paper, the cavitation damage in polymer solutions is made with a vibratory cavitation apparatus, and it is shown that the Cavitation damage is subject to the effective influence of elastic properties of liquids.
Abstract: Cavitation damage tests in polymer solutions are made with a vibratory cavitation apparatus. It is possible for this device to suppress the degradation of polymer by ultrasonic cavitation. Polymer solutions used are 100 wppm, 500 wppm, and 1000 wppm solutions of Polyox. The weight loss in 100 wppm Polyox solution is larger than that in water, but in 500 wppm and 1000 wppm Polyox solutions the weight losses after 60 min exposure to cavitation are relatively small. It is indicated that the cavitation damage in polymer solutions is subject to the effective influence of elastic properties of liquids.