A COMPUTATIONAL STUDY OF IN-CYLINDER FLOW CHARACTERISTICS IN TWO STROKE SIE WITH DOUBLE INTAKE MANIFOLDS AT DIFFERENT INCLINATION ANGLES

2014 ◽  
Vol 16 (16) ◽  
pp. 1-14 ◽  
Author(s):  
M. Radwan ◽  
O. Abu El-Yazeed ◽  
I. Elbadawy ◽  
M. Gad
Keyword(s):  
Computational Study ◽  
Flow Characteristics ◽  
Inclination Angles ◽  
Cylinder Flow

Investigation of Swirl Ratio Impact on In-Cylinder Flow in a SIDI Optical Engine

2015 ◽  
Author(s):  
Hanyang Zhuang ◽  
David L. S. Hung ◽  
Jie Yang ◽  
Shaoxiong Tian
Keyword(s):  
Flow Field ◽  
Soot Formation ◽  
Flow Characteristics ◽  
Control Valve ◽  
Exhaust Emission ◽  
Swirl Ratio ◽  
Optical Engine ◽  
Crank Angle ◽  
Cylinder Flow ◽  
Intake Swirl

Advanced powertrain technologies have improved engine performance with higher power output, lower exhaust emission, and better controllability. Chief among them is the development of spark-ignition direct-injection (SIDI) engines in which the in-cylinder processes control the air flow motion, fuel-air mixture formation, combustion, and soot formation. Specifically, intake air with strong swirl motion is usually introduced to form a directional in-cylinder flow field. This approach improves the mixing process of air and fuel as well as the propagation of flame. In this study, the effect of intake air swirl on in-cylinder flow characteristics was experimentally investigated. High speed particle image velocimetry (PIV) was conducted in an optical SIDI engine to record the flow field on a swirl plane. The intake air swirl motion was achieved by adjusting the opening of a swirl ratio control valve which was installed in one of the two intake ports in the optical engine. Ten opening angles of the swirl ratio control valve were adjusted to produce an intake swirl ratio from 0.55 to 5.68. The flow structures at the same crank angle degree, but under different swirl ratio, were compared and analyzed using proper orthogonal decomposition (POD). The flow dominant structures and variation structures were interpreted by different POD modes. The first POD mode captured the most dominant flow field structure characteristics; the corresponding mode coefficients showed good linearity with the measured swirl ratio at the compression stroke when the flow was swirling and steady. During the intake stroke, strong intake air motion took place, and the structures and coefficients of the first modes varied along different swirl ratio. These modes captured the flow properties affected by the intake swirl motion. Meanwhile, the second and higher modes captured the variation feature of the flow at various crank angle degrees. In summary, this paper demonstrated a promising approach of using POD to interpret the effectiveness of swirl control valve on in-cylinder swirl flow characteristics, providing better understanding for engine intake system design and optimization.

scholarly journals Adverse Hemodynamic Conditions Associated with Mechanical Heart Valve Leaflet Immobility

2018 ◽  
Vol 5 (3) ◽  
pp. 74 ◽  
Author(s):  
Fardin Khalili ◽  
Peshala Gamage ◽  
Richard Sandler ◽  
Hansen Mansy
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Computational Study ◽  
Cell Damage ◽  
Mechanical Heart Valve ◽  
Flow Characteristics ◽  
Maximal Velocity ◽  
Valve Dysfunction ◽  
Promising Tool ◽  
Artificial Heart Valves

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.

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

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.

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

2010 ◽  
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.

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

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.

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

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.

Square-Cylinder Flow Characteristics Modulated Using Upstream Control Rod

2012 ◽  
Vol 28 (2) ◽  
pp. 279-289 ◽  
Author(s):  
S. C. Yen ◽  
S. F. Wu
Keyword(s):  
Surface Pressure ◽  
Vortex Shedding ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Square Cylinder ◽  
Control Rod ◽  
Pressure Profiles ◽  
Spacing Ratio ◽  
Cylinder Flow ◽  
Upstream Control

AbstractThe flow patterns, vortex-shedding frequency and aerodynamic performance of the square-cylinder flow were modulated using an upstream control rod. Additionally, the flow behaviors were examined using various Reynolds numbers, rotation angles, and spacing ratios. The flow patterns were visualized using the smoke-wire scheme. The global velocity fields and streamline patterns were analyzed using the particle image velocimetry (PIV). Additionally, the flow modes were characterized based on the kinematics theory. Moreover, the vortex-shedding frequencies behind upstream control rod and the square cylinder were detected using two hot-wire anemometers. The surface pressure on square cylinder was determined using a linear pressure scanner. Then, the aerodynamic parameters were calculated using the surface-pressure profiles. Three characteristic flow modes — single, attached, and bi-vortex-street — were categorized by varying the Reynolds number and spacing ratio. In the attached mode, the position of upstream control rod determined the flow characteristics. Furthermore, in the attached mode, the mean drag force of the square cylinder is about 57% lower than of single-square cylinder.

Experimental and Computational Study of Flow Characteristics in a Drilled Perforated Core

2012 ◽  
Author(s):  
Datong Sun ◽  
Rajani Satti ◽  
Darren Ochsner ◽  
Tim Sampson ◽  
Baoyan Li ◽  
...  
Keyword(s):  
Computational Study ◽  
Flow Characteristics
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