NUMERICAL STUDY OF SECONDARY FLOW OF A LIQUID-LIQUID TWO PHASE FLUID THROUGH A PIPE BEND WITH SQUARE CROSS-SECTIONAL AREA

2019 ◽  
Author(s):  
J. Manzanares ◽  
O. F. Ayala ◽  
O. M. Ayala
Keyword(s):  
Secondary Flow ◽  
Numerical Study ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Two Phase ◽  
Pipe Bend ◽  
Cross Sectional ◽  
Phase Fluid

scholarly journals Numerical Investigation of a two-inlet PVT air collector

2019 ◽  
Vol 136 ◽  
pp. 05014
Author(s):  
Zhangyang Kang ◽  
Zhaoyang Lu ◽  
Xin Deng ◽  
Qiongqiong Yao
Keyword(s):  
Heat Transfer ◽  
Single Channel ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Thermal Characteristics ◽  
Area Ratio ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Maximum Heat

A numerical study of heat and mass transfer characteristics of a two-inlet PV/T air collector is performed. The influence of thermal characteristics and efficiency is investigated as the area ratios of inlet and outlet of the single channel with two inlets are changed. The design of the two-inlet PV/T air collector can avoid the poor heat transfer conditions of the single inlet PV/T air collector and improve the total photo-thermal efficiency. When the inlet/outlet cross-sectional area ratio is reduced, the inlet air from the second inlet enhances the convection heat transfer in the second duct and the temperature distribution is more uniform. As the cross-sectional area of the second inlet increase, the maximum heat exchange amount of the two-inlet PV/T air collector occurs between the inlet and outlet cross-sectional area ratio L=0.645 and L=0.562.

scholarly journals Nondimensional translational characteristics of elastomer components

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Andreas Dutzler ◽  
◽  
Christian Buzzi ◽  
Martin Leitner ◽  
◽  
...  
Keyword(s):  
Elastic Properties ◽  
Numerical Study ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Component Size ◽  
Rail Vehicles ◽  
Force Displacement

Elastomer components are used in both primary and secondary spring stages in bogies of rail vehicles. The design of spring components of a bogie requires knowledge of the calculation of the elastic properties of these components. An elastomer spring component is typically analyzed in the dimension to be investigated. Calculated force-displacement curves are directly related to the material and dimension of the component itself. The objective of this paper is to establish generalized or, in other words, universally valid force-displacement characteristics by breaking the entanglement with component size. The advantage of this approach is the extended validity of the results for a specific spring shape of any size. The simulations are performed only once for each shape and may be converted to any other size using the proposed methodology. A numerical study of a layer spring with rectangular cross-sectional area and fixed edges on both top and bottom sides serves as a reference example.

Effects of Volute Cross-Sectional Area Distribution on Performance of Double-Suction Volute Pump

2019 ◽  
Author(s):  
Szu Yung Chen ◽  
Lu Zhang ◽  
Yumiko Sekino ◽  
Hiroyoshi Watanabe
Keyword(s):  
Fluid Dynamics ◽  
Genetic Algorithm ◽  
Computational Fluid Dynamics ◽  
Secondary Flow ◽  
Cross Sections ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Suction Pump ◽  
Computational Fluid Dynamics Cfd

Abstract The following study describes the optimization design procedure of a double-suction pump. BASELINE pump is designed as inlet nozzle diameter 800 mm and impeller outlet diameter 740 mm. Each component of a BASELINE pump, impeller configurations, discharge volute, and the suction casing were determined by DOE (Design of Experiments) and sensitivity analysis. However, finite selected design parameters for each component are mostly restricted to the free surface design of the pump casing. In this study, the optimization method approach along with steady Computational Fluid Dynamics (CFD) is introduced to achieve the high efficiency request of a double-suction pump. To investigate the matching optimization of the impeller and discharge volute at design point, the full parametric geometry of discharge volute was developed referred to the BASELINE shape and Multi-Objective Genetic Algorithm NSGA-II (Non-dominated Sorting Genetic Algorithm II) was used. Optimization result shows that by increasing the volute cross-sectional area from the volute tongue till the circumferential angle 180 deg. provides lower loss. This is due to the improvement achieved for the better distribution of the velocity gradient within the volute. A validated unsteady computational fluid dynamics (CFD) was also employed to investigate the performance difference between optimized volute design and the BASELINE which correlated to the pressure fluctuation and secondary flow behavior inside the cross-sections from 80% to 120% of nominal flow rate. The result shows that the flow distortion in the streamwise direction is stronger with the BASELINE and sensitively affects the operation stability. This is due to the different secondary flow pattern in the cross-sections, hence demonstrating a design direction of desired volute cross-sectional shape for high-performance can be used in a double-suction volute pump.

Numerical Study on the Flow Past a Twisted Elliptic Cylinder With Subcritical Reynolds Number

2011 ◽  
Author(s):  
Min Ho Kim ◽  
Jin Woog Lee ◽  
Hyun Sik Yoon ◽  
Man Yeong Ha
Keyword(s):  
Reynolds Number ◽  
Numerical Study ◽  
Elliptic Cylinder ◽  
Cross Sectional Area ◽  
Stream Velocity ◽  
Spanwise Direction ◽  
Sectional Area ◽  
Cross Sectional ◽  
Flow Past ◽  
Smooth Cylinder

Large eddy simulation of flow past a torsional cylinder has been carried out at a Reynolds number of 3900 based on the cylinder diameter and the free stream velocity using finite volume method. The torsional cylinder has been formed by rotating the elliptic cross sectional area along the spanwise direction. For an ellipse, different eccentricities are considered to observe the effect of eccentricity on the flow fields. The excellent comparisons with previous studies for the cases of a smooth cylinder and a wavy cylinder having sinusoidal variation in cross sectional area along the spanwise direction guarantee the accuracy of present numerical methods. The effect of eccentricity on the drag and lift coefficients representing the fluid flow characteristics has been investigated by comparing with those of the smooth cylinder, resulting in enhancement of drag reduction and suppression of vortex-induced vibration. The isosurface of swirling strength has been adopted to identify the vortical structures in the turbulent wake.

Effects of the Cross-Sectional Area of a Volute on Suction Recirculation and Cavitation in a Centrifugal Pump

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Hyeon-Seok Shim ◽  
Kwang-Yong Kim
Keyword(s):  
Centrifugal Pump ◽  
Three Dimensional ◽  
Cross Sectional Area ◽  
Navier Stokes ◽  
Sectional Area ◽  
Two Phase ◽  
Cross Sectional ◽  
Sst Model ◽  
The Cross ◽  
Critical Cavitation

Abstract The effects of the cross-sectional area of a volute on suction recirculation and cavitation in a centrifugal pump were investigated. The pump performance and fluid flow were analyzed using both steady and unsteady three-dimensional Reynolds-averaged Navier–Stokes analyses. The shear stress transport (SST) model was adopted as a turbulence closure model, and a simplified Rayleigh–Plesset cavitation model and a homogeneous two-phase mixture model were used to simulate the cavitating flow inside the pump. A constant to determine the designed circumferential velocity of the volute was selected as the geometric parameter for a parametric study. The hydraulic efficiency, head coefficient, blockage in front of the impeller, and critical cavitation number for a head-drop of 3% were selected as the performance parameters to evaluate the hydraulic performance. The results show that unlike the blockage, the hydraulic and suction performances were affected significantly by the volute shape. Both steady and unsteady flow analyses showed that the onset and development of suction recirculation were relatively unaffected by the volute geometry and the best efficiency point of the pump.

Research on AirFlush®: distribution of water and air in tubular and capillary membrane modules

2003 ◽  
Vol 3 (5-6) ◽  
pp. 409-414 ◽  
Author(s):  
J. Verberk ◽  
H. van Dijk
Keyword(s):  
Cross Sectional Area ◽  
Air Distribution ◽  
Phase Flow ◽  
Sectional Area ◽  
Two Phase ◽  
Cross Sectional ◽  
Dead End ◽  
Capillary Membrane ◽  
Membrane Modules ◽  
The Cross

Dead-end ultrafiltration has proved itself as a technique for reclamation of backwash water of sand filters and as a pretreatment step before spiral wound reverse osmosis. A direct result of dead-end filtration is a flux decrease in time caused by the accumulation of material in the membrane pores and on the membrane surface. Different cleaning techniques are used to remove this accumulated material. Recently a new technique has been introduced, the AirFlush®. This technique makes use of air to create higher turbulence as compared to a water flush. At Delft University of Technology in co-operation with X-flow and Norit Membrane Technology research has been started into the fundamentals of the combined air and water flush. As in many industrial processes, an equal division of water and air over an installation is very important. To check the distribution of water and air over the cross-sectional area of tubular and capillary membrane modules two different test installations have been built. The results from the experiments show that for tubular membrane modules the water and air distribution over the cross-sectional area of the module is not always equally divided. Improvements have to be obtained by a better air distribution system. For capillary membrane modules the distribution of water and air over the cross-sectional area is more equally divided. The results from the experiments are discussed taking into account the theory of two-phase flow. It is shown that from the theory of two-phase flow the good distribution for the capillary membrane module can be explained by the large frictional pressure drop compared to the hydrostatic pressure drop.

EXPERIMENTAL ANALYSIS OF TWO-PHASE EJECTOR SYSTEM WITH VARYING MIXING CROSS-SECTIONAL AREA USING NATURAL REFRIGERANT CO2

2010 ◽  
Vol 18 (04) ◽  
pp. 297-307 ◽  
Author(s):  
MASAFUMI NAKAGAWA ◽  
ARIEL R. MARASIGAN ◽  
TAKANORI MATSUKAWA
Keyword(s):  
Cross Sectional Area ◽  
Pressure Recovery ◽  
Inlet Pressure ◽  
Inlet Temperature ◽  
Sectional Area ◽  
Two Phase ◽  
Entrainment Ratio ◽  
Evaporator Temperature ◽  
Cross Sectional ◽  
Ejector System

The use of two-phase ejector in improving the performance of transcritical CO2 refrigeration system needs further experimental verification particularly the effects of its geometrical design. In this study, experimental data were gathered for ejectors with different mixing cross-sectional areas at different operating temperature and pressure. The results have shown that a smaller mixing area yields higher efficiency due to its higher pressure recovery and entrainment ratio, but its advantages are limited to lower ejector inlet pressure Pc. A larger mixing area is required for higher cooling capacity which can be achieved at higher ejector inlet pressure or lower ejector inlet temperature but excessive increase in this area considerably decreases the efficiency of the system. In this study, the ejector with the largest mixing area was the most inefficient and reduced the COP up to 10% compared to most efficient type. It demonstrates the significant effect of ejector's geometrical features, particularly the mixing cross-sectional area and its related geometrical ratio, in the performance of CO2 ejector system. The effect of motive nozzle inlet condition on pressure recovery profile has been more evident for ejector with smaller mixing area while the evaporator temperature has the least effect in the performance of the system. In the conditions used in this study, using ejector yielded a COP improvement of up to 35% compared to the conventional system.

Pelvic Canal Narrowing Caused by Triple Pelvic Osteotomy in the Dog

1994 ◽  
Vol 07 (03) ◽  
pp. 110-113 ◽  
Author(s):  
D. L. Holmberg ◽  
M. B. Hurtig ◽  
H. R. Sukhiani
Keyword(s):  
Postoperative Complications ◽  
Pelvic Osteotomy ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Canal Width ◽  
Operative Complications ◽  
Post Operative Complications

SummaryDuring a triple pelvic osteotomy, rotation of the free acetabular segment causes the pubic remnant on the acetabulum to rotate into the pelvic canal. The resulting narrowing may cause complications by impingement on the organs within the pelvic canal. Triple pelvic osteotomies were performed on ten cadaver pelves with pubic remnants equal to 0, 25, and 50% of the hemi-pubic length and angles of acetabular rotation of 20, 30, and 40 degrees. All combinations of pubic remnant lengths and angles of acetabular rotation caused a significant reduction in pelvic canal-width and cross-sectional area, when compared to the inact pelvis. Zero, 25, and 50% pubic remnants result in 15, 35, and 50% reductions in pelvic canal width respectively. Overrotation of the acetabulum should be avoided and the pubic remnant on the acetabular segment should be minimized to reduce postoperative complications due to pelvic canal narrowing.When performing triple pelvic osteotomies, the length of the pubic remnant on the acetabular segment and the angle of acetabular rotation both significantly narrow the pelvic canal. To reduce post-operative complications, due to narrowing of the pelvic canal, overrotation of the acetabulum should be avoided and the length of the pubic remnant should be minimized.

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