Computational Study on the Flow Characteristics in a Film Cooled Dual-Bell Nozzle

Artificial heart valves may dysfunction, leading to thrombus and/or pannus formations. Computational fluid dynamics is a promising tool for improved understanding of heart valve hemodynamics that quantify detailed flow velocities and turbulent stresses to complement Doppler measurements. This combined information can assist in choosing optimal prosthesis for individual patients, aiding in the development of improved valve designs, and illuminating subtle changes to help guide more timely early intervention of valve dysfunction. In this computational study, flow characteristics around a bileaflet mechanical heart valve were investigated. The study focused on the hemodynamic effects of leaflet immobility, specifically, where one leaflet does not fully open. Results showed that leaflet immobility increased the principal turbulent stresses (up to 400%), and increased forces and moments on both leaflets (up to 600% and 4000%, respectively). These unfavorable conditions elevate the risk of blood cell damage and platelet activation, which are known to cascade to more severe leaflet dysfunction. Leaflet immobility appeared to cause maximal velocity within the lateral orifices. This points to the possible importance of measuring maximal velocity at the lateral orifices by Doppler ultrasound (in addition to the central orifice, which is current practice) to determine accurate pressure gradients as markers of valve dysfunction.

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Computational study on the aerodynamics of a long-shrouded contra-rotating rotor in hover

International Journal of Micro Air Vehicles ◽

10.1177/1756829319833686 ◽

2019 ◽

Vol 11 ◽

pp. 175682931983368

Author(s):

Chao Huo ◽

Peng Lv ◽

Anbang Sun

Keyword(s):

Flow Field ◽

Opposite Direction ◽

Computational Study ◽

Flow Characteristics ◽

The Other ◽

Complex Flow ◽

Sliding Mesh ◽

Global Performance ◽

Mesh Method ◽

Downstream Flow

This paper aims to investigate the aerodynamics including the global performance and flow characteristics of a long-shrouded contra-rotating rotor by developing a full 3D RANS computation. Through validations by current experiments on the same shrouded contra-rotating rotor, the computation using sliding mesh method and the computational zone with an extended nozzle downstream flow field effectively works; the time-averaged solution of the unsteady computation reveals that more uniform flow presents after the downstream rotor, which implies that the rear rotor rotating at opposite direction greatly compensates and reduces the wake; the unsteady computations further explore the flow field throughout the whole system, along the span and around blade tips. Complex flow patterns including the vortices and their interactions are indicated around the blade roots and tips. For further identifying rotor configurations, the rotor–rotor distance and switching two rotor speeds were studied. The computation reveals that setting the second rotor backwards decreases the wake scale but increases its intensity in the downstream nozzle zone. However, for the effect of switching speeds, computations cannot precisely solve the flow when the rear rotor under the windmill because of the upstream rotor rotating much faster than the other one. All the phenomena from computations well implement the experimental observations.

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2508 Flow Characteristics of Two-Dimensional Compressed Dual Bell Nozzle Models during the Startup and Shutdown Transients

The proceedings of the JSME annual meeting ◽

10.1299/jsmemecjo.2006.2.0_223 ◽

2006 ◽

Vol 2006.2 (0) ◽

pp. 223-224

Author(s):

Shinji SHIMIZU ◽

Kazuhiko YOKOTA ◽

Motoyuki ITOH ◽

Shinji TAMANO

Keyword(s):

Flow Characteristics ◽

Two Dimensional ◽

Dual Bell

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A Computational Study on the Effect of Angles of Attack on a Double-Cone Type Supersonic Inlet With Bleeding System

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Education; Electric Power; Manufacturing Materials and Metallurgy ◽

10.1115/gt2010-23221 ◽

2010 ◽

Cited By ~ 1

Author(s):

Kyung Jin Ryu ◽

Seol Lim ◽

Sang Dug Kim ◽

Dong Joo Song

Keyword(s):

Boundary Layer ◽

Flow Field ◽

Computational Study ◽

Angle Of Attack ◽

Flow Characteristics ◽

Uniform Flow ◽

Double Cone ◽

Interface Plane ◽

Supersonic Inlet ◽

Cone Type

The flow characteristics on a supersonic inlet with bleeding system at various angles of attack are studied by using computational 3D turbulent flow analysis. A turbulent CSCM compressible upwind flux difference splitting Navier-Stokes method with k-w turbulence model is used to compute the inlet flowfields. MPICH-2.0 library and PC-cluster system are used to reduce computational times. Distortion and average of total pressure recovery at the AIP (aerodynamic interface plane) are used as evaluation criteria of inlet performance. The flow characteristics at zero of angle of attack of double-cone type supersonic inlet without and with bleeding system have been compared. Without bleeding system inlet with the strong SBLI (shock/boundary-layer interaction) induces slow flow recovery near the throat and produces very thick boundary layer downstream. But the bleeding system successfully removes the low energy flow from the boundary layer near the throat. As the angle of attack at the AIP because large, we can see more non-uniform flow field, and the non-uniform flow field is the major aggravating factor of inlet performance.

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A computational study on the flow characteristics of a self-compensating liquid balancer

Journal of Mechanical Science and Technology ◽

10.1007/s12206-011-0407-y ◽

2011 ◽

Vol 25 (6) ◽

pp. 1465-1474 ◽

Cited By ~ 6

Author(s):

Chung-Hyo Jung ◽

Jin-Tak Kim ◽

Yun-Ho Choi

Keyword(s):

Computational Study ◽

Flow Characteristics

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Investigation on Flow Characteristics and Performance of a Vertical Axis Wind Turbine With Deflector Plates

Volume 2: Combustion, Fuels, and Emissions; Renewable Energy: Solar and Wind; Inlets and Exhausts; Emerging Technologies: Hybrid Electric Propulsion and Alternate Power Generation; GT Operation and Maintenance; Materials and Manufacturing (Including Coatings, Composites, CMCs, Additive Manufacturing); Analytics and Digital Solutions for Gas Turbines/Rotating Machinery ◽

10.1115/gtindia2019-2471 ◽

2019 ◽

Author(s):

K. Karthik Selva Kumar ◽

Vinayak Kulkarni ◽

Niranjan Sahoo

Keyword(s):

Wind Turbine ◽

Computational Study ◽

Flow Characteristics ◽

Vertical Axis ◽

Vertical Axis Wind Turbine ◽

Near Wake ◽

Flow Phenomenon ◽

Sliding Mesh ◽

And Performance ◽

Accelerated Flow

Abstract In this article, a 3D computational study has been performed to understand the flow phenomenon over the vertical axis wind turbine with a three-bladed NACA0021. The rotary motion of the VAWT simulated with sliding mesh techniques with reference to the SST-Kω turbulence model using the CFD software. The observed results were found to be having a significant improvement in the enhancement of the power output. Also, the investigation was move forwarded to understand the flow characteristics of the VAWT with the presence of deflector plates in different orientation at the upstream conditions. The present of deflector plates creates an augmented flow phenomenon which creates an accelerated flow at the near wake region, causing a significant improvement in the coefficient of power of the wind turbine.

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Multiphase Flow Investigation of a Centrifugal Filter Using Computational Fluid Dynamics and Experiments

Computational Technologies for Fluid/Thermal/Structural/Chemical Systems With Industrial Applications, Volume 1 ◽

10.1115/pvp2002-1570 ◽

2002 ◽

Author(s):

Steven D. Megson ◽

Michael Wilson ◽

Stuart A. MacGregor

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Computational Study ◽

Flow Characteristics ◽

High Tech ◽

Outlet Channel ◽

Two Phase ◽

Base Oil ◽

Factors Affecting ◽

Cfd Models

Modern “high tech” lubricant oils have been developed to contain a high level of dispersant additive to the base oil. As contaminant loading has increased, designers are required to address the problem of controlling the contamination found in the oil. One method is the use of bypass centrifugal sedimentation. This paper describes a computational study of the basic flow characteristics in a centrifugal sedimenting rotor using the computational fluid dynamics (CFD) package STAR-CD. Simplified CFD models have indicated regions of flow which would be difficult to demonstrate by experimental methods alone. For example, backflow from the outlet channel is found to cause a disruptive secondary flow in some models, but this flow is contained by the inclusion of a more realistic geometry. Two–phase flow computations have also been carried out to investigate the behaviour of spherical particulates of different sizes. Flow and geometry factors affecting the centrifuge performance are discussed.

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