Inlet velocity profile effects on turbulent swirling flow predictions

1994 ◽  
Vol 10 (2) ◽  
pp. 155-160 ◽  
Author(s):  
Mingchun Dong ◽  
David G. Lilley
Keyword(s):  
Velocity Profile ◽  
Swirling Flow ◽  
Inlet Velocity

Inlet Velocity Profile Optimization of the Turbine 99 Draft Tube

2013 ◽  
Author(s):  
Sergio Galván ◽  
Marcelo Reggio ◽  
Francois Guibault
Keyword(s):  
Velocity Profile ◽  
Swirling Flow ◽  
Draft Tube ◽  
Flow Characteristics ◽  
Hydraulic Turbine ◽  
Tube Flow ◽  
Inlet Velocity ◽  
Runner Design ◽  
Profile Optimization ◽  
Direct Outcome

In recent years, several investigations on hydraulic turbine draft tube performance have shown that the hydrodynamic field at the runner’s outlet is a direct outcome of the runner design and the operating point. This has shown the dependence of the diffuser efficiency on the flow rate and the inlet swirling flow intensity, mostly on turbines that present low head (high specific velocity) and operate away from their best efficiency point. The numerical optimization of the inlet velocity profile is presented as an attempt to control these two inlet flow characteristics. The goal is the improvement of the flow through the draft tube to allow for better turbine performance. This methodology is based on the automatic coupling of several commercial softwares and is used to manipulate the analytical representation of the swirling flow, which has led to the minimization of hydraulic losses. Also, a qualitative and quantitative analysis of the draft tube flow field provoked by a redesigned inlet velocity profiles, has helped to understand how it is possible to suppress or at least mitigate undesirable draft tube flow characteristics.

Mean Flow Measurements Near the Plane of an Open Rotor Operating with an Inlet Velocity Gradient

1981 ◽  
Vol 103 (2) ◽  
pp. 445-450
Author(s):  
M. L. Billet
Keyword(s):  
Flow Field ◽  
Velocity Profile ◽  
Velocity Gradient ◽  
Vortex Motion ◽  
Field Measurements ◽  
Velocity Data ◽  
Mean Flow ◽  
Flow Measurements ◽  
Inlet Velocity ◽  
Open Rotor

As part of a study on the structure of a trailing vortex, laser doppler anemometer (LDA) measurements were made of the flow field near an open rotor having an inlet velocity gradient. The measurements were made in the 1.22 m dia water tunnel of the Applied Research Laboratory at The Pennsylvania State University. Velocity data were obtained for rotor inlet and outlet flow fields for several different inlet velocity gradients. Velocity data were also obtained downstream of the rotor plane that shows the vortex structure. Flow field measurements show the development of the downstream vortex motion. Small variations in the inlet velocity gradient near the rotor wall caused large differences in the structure of the trailing vortex. In addition, a measured downstream velocity profile is compared with a calculated velocity profile.

The Reynold’s Number Effect in High Swirling Flow in Unconfined Burner

2015 ◽  
Vol 72 (4) ◽  
Author(s):  
Norwazan A. R. ◽  
Mohammad Nazri Mohd. Jaafar
Keyword(s):  
Turbulent Flows ◽  
Gas Turbines ◽  
Swirling Flow ◽  
Numerical Study ◽  
Isothermal Condition ◽  
Navier Stokes ◽  
Reacting Flow ◽  
Ansys Fluent ◽  
Inlet Velocity ◽  
Burner Exit

The numerical simulations of swirling turbulent flows in isothermal condition in combustion chamber of burner were investigated. The aim is to characterize the main flow structures and turbulence in a combustor that is relevant to gas turbines. Isothermal flows with different inlet flow velocities were considered to demonstrate the effect of radial velocity. The inlet velocity, Uo is varied from 30 m/s to 60 m/s represent a high Reynolds number up to 3.00 X 105. The swirler was located at the upstream of combustor with the swirl number of 0.895. A numerical study of non-reacting flow in the burner region was performed using ANSYS Fluent. The Reynolds–Averaged Navier–Stokes (RANS) approach method was applied with the standard k-ɛ turbulence equations. The various velocity profiles were different after undergoing the different inlet velocity up to the burner exit. The results of velocity profile showed that the high U0 give better swirling flow patterns.

Flow Development in a Circular Duct With a Highly Distorted Inlet Condition

2007 ◽  
Author(s):  
Srinivas Badam ◽  
Jie Cui ◽  
Stephen Idem
Keyword(s):  
Numerical Model ◽  
Velocity Profile ◽  
Reynolds Numbers ◽  
Velocity Profiles ◽  
Pressure Gradients ◽  
Development Length ◽  
Circular Duct ◽  
Inlet Velocity ◽  
Inlet Condition ◽  
Flow Development

The development of air flow downstream of a stationary fan located in a circular duct was investigated. The objective of the research was to study the evolution of the velocity profiles and pressure gradients at various axial locations. The velocity profiles were measured at three different Reynolds numbers using a five-hole directional probe. Because the stationary fan caused the inlet velocity profile to be highly distorted, it was determined experimentally that the development length exceeded 20 duct diameters. Since this was greater than the length of the apparatus, a corresponding numerical model of the flow was generated using the commercial CFD software Fluent-6.1/6.2. The numerical model was validated against the experimental results. The hydrodynamic development length was therein determined numerically.

511 Three Dimensional Separation with Focus in a Decelerating Duct Flow : Relation with the Gradient of Inlet Velocity Profile

2001 ◽  
Vol 2001.54 (0) ◽  
pp. 139-140
Author(s):  
Yoichi KINOUE ◽  
Toshiaki SETOGUCHI ◽  
Kenji KANEKO ◽  
Takeshi MURASAKI ◽  
Masahiro INOUE
Keyword(s):  
Velocity Profile ◽  
Three Dimensional ◽  
Duct Flow ◽  
Inlet Velocity

scholarly journals Aerodynamic Research on Straight Wall Annular Diffuser for Turbofan Augmentor

1985 ◽  
Author(s):  
Q. M. Xie ◽  
J. G. Gu
Keyword(s):  
Velocity Profile ◽  
Temperature Profile ◽  
Aerodynamic Performance ◽  
Recovery Coefficient ◽  
Momentum Ratio ◽  
Inlet Velocity ◽  
Straight Wall ◽  
Annular Diffuser ◽  
Aerodynamic Test ◽  
Pressure Recovery Coefficient

The effect of non-uniform inlet velocity and temperature profile on the aerodynamic performance of straight wall annular diffuser for turbofan augmentor has been investigated. The distribution of static pressure, stagnation pressure and temperature has been measured, thus pressure recovery coefficient, velocity profile and temperature profile at different axial station along the diffuser center line can be determined. The experimental results showed that the momentum ratio ρ¯eV¯e2/ρ¯iV¯i2 of two streams across the diffuser inlet flow splitter is the non-dimensional flow parameter controlling diffuser aerodynamic performance. Thus, it is possible to simulate turbofan augmentor annular diffuser perfomance by using low temperature air flow aerodynamic test under the condition that the diffusers are of similar geometry, have the same inlet velocity profile and maintain the momentum ratio constant. A correlation for the velocity distribution in the diffuser was also obtained.

scholarly journals Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms: The Impact of Patient-Specific Inflow Conditions and Fluid/Solid Coupling

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Santanu Chandra ◽  
Samarth S. Raut ◽  
Anirban Jana ◽  
Robert W. Biederman ◽  
Mark Doyle ◽  
...  
Keyword(s):  
Velocity Profile ◽  
Boundary Conditions ◽  
Fluid Structure Interaction ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Fluid Structure ◽  
Inlet Velocity ◽  
Structure Interaction ◽  
Biomechanical Assessment ◽  
Fully Coupled

Rupture risk assessment of abdominal aortic aneurysms (AAA) by means of biomechanical analysis is a viable alternative to the traditional clinical practice of using a critical diameter for recommending elective repair. However, an accurate prediction of biomechanical parameters, such as mechanical stress, strain, and shear stress, is possible if the AAA models and boundary conditions are truly patient specific. In this work, we present a complete fluid-structure interaction (FSI) framework for patient-specific AAA passive mechanics assessment that utilizes individualized inflow and outflow boundary conditions. The purpose of the study is two-fold: (1) to develop a novel semiautomated methodology that derives velocity components from phase-contrast magnetic resonance images (PC-MRI) in the infrarenal aorta and successfully apply it as an inflow boundary condition for a patient-specific fully coupled FSI analysis and (2) to apply a one-way–coupled FSI analysis and test its efficiency compared to transient computational solid stress and fully coupled FSI analyses for the estimation of AAA biomechanical parameters. For a fully coupled FSI simulation, our results indicate that an inlet velocity profile modeled with three patient-specific velocity components and a velocity profile modeled with only the axial velocity component yield nearly identical maximum principal stress (σ1), maximum principal strain (ε1), and wall shear stress (WSS) distributions. An inlet Womersley velocity profile leads to a 5% difference in peak σ1, 3% in peak ε1, and 14% in peak WSS compared to the three-component inlet velocity profile in the fully coupled FSI analysis. The peak wall stress and strain were found to be in phase with the systolic inlet flow rate, therefore indicating the necessity to capture the patient-specific hemodynamics by means of FSI modeling. The proposed one-way–coupled FSI approach showed potential for reasonably accurate biomechanical assessment with less computational effort, leading to differences in peak σ1, ε1, and WSS of 14%, 4%, and 18%, respectively, compared to the axial component inlet velocity profile in the fully coupled FSI analysis. The transient computational solid stress approach yielded significantly higher differences in these parameters and is not recommended for accurate assessment of AAA wall passive mechanics. This work demonstrates the influence of the flow dynamics resulting from patient-specific inflow boundary conditions on AAA biomechanical assessment and describes methods to evaluate it through fully coupled and one-way–coupled fluid-structure interaction analysis.

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