Three-dimensional study of turbulent flow characteristics of an offset plane jet with variable density

2015 ◽  
Vol 52 (11) ◽  
pp. 2327-2343 ◽  
Author(s):  
Ali Assoudi ◽  
Sabra Habli ◽  
Nejla Mahjoub Saïd ◽  
Hervé Bournot ◽  
Georges Le Palec
Keyword(s):  
Turbulent Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Variable Density ◽  
Plane Jet

scholarly journals Interactions between Tandem Cylinders in an Open Channel: Impact on Mean and Turbulent Flow Characteristics

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1718
Author(s):  
Hasan Zobeyer ◽  
Abul B. M. Baki ◽  
Saika Nowshin Nowrin
Keyword(s):  
Turbulent Flow ◽  
Open Channel ◽  
Recirculation Zone ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Recirculation ◽  
Tandem Cylinders ◽  
Flow Development ◽  
The Mean ◽  
Recirculation Length

The flow hydrodynamics around a single cylinder differ significantly from the flow fields around two cylinders in a tandem or side-by-side arrangement. In this study, the experimental results on the mean and turbulence characteristics of flow generated by a pair of cylinders placed in tandem in an open-channel flume are presented. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components. This study investigated the effect of cylinder spacing at 3D, 6D, and 9D (center to center) distances on the mean and turbulent flow profiles and the distribution of near-bed shear stress behind the tandem cylinders in the plane of symmetry, where D is the cylinder diameter. The results revealed that the downstream cylinder influenced the flow development between cylinders (i.e., midstream) with 3D, 6D, and 9D spacing. However, the downstream cylinder controlled the flow recirculation length midstream for the 3D distance and showed zero interruption in the 6D and 9D distances. The peak of the turbulent metrics generally occurred near the end of the recirculation zone in all scenarios.

CFD Analysis of Turbulent Flow in a Nuclear Fuel Bundle With Mixing Vane

2002 ◽  
Author(s):  
Wang Kee In ◽  
Dong Seok Oh ◽  
Tae Hyun Chun
Keyword(s):  
Turbulent Flow ◽  
Nuclear Fuel ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cfd Analysis ◽  
Mean Flow ◽  
Cfd Models ◽  
Fuel Bundle ◽  
Rod Array

A computational fluid dynamics (CFD) analysis was performed to investigate the coolant mixing in a nuclear fuel bundle that is promoted by the mixing vane on the grid spacer. Single and multiple subchannels of one grid span of the fuel bundle were modeled to simulate a 5×5 rod array experiment with the mixing vane. The three-dimensional CFD models were generated by a structured multi-block method. The standard k-ε turbulence model was used in the current CFD simulation since it is practically useful and converges well for the complex turbulent flow in a nuclear fuel bundle. The CFD predictions of axial and lateral mean flow velocities showed a somewhat large difference from the experimental results near the spacer but represented the overall characteristics of coolant mixing well in a nuclear fuel bundle with the mixing vane. Comparison of single and multiple subchannel predictions shows good agreement of the flow characteristics in the central subchannel of the rod array. The simulation of multiple subchannels shows a slightly off-centered swirl in the peripheral subchannels due to the external wall of the rod array. It also shows no significant swirl and crossflow in the wall subchannels and the corner subchannels.

Flow Characteristics Within and Downstream of Spherical and Cylindrical Dimple on a Flat Plate at Low Reynolds Numbers

2004 ◽  
Author(s):  
A. Khalatov ◽  
A. Byerley ◽  
D. Ochoa ◽  
Seong-Ki Min
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Flow Patterns ◽  
Flow Features ◽  
Laminar And Turbulent Flow ◽  
Low Reynolds ◽  
Oscillation Frequencies

A comprehensive experimental study has been performed in the U.S. Air Force Academy water tunnel to obtain a better understanding of the complicated flow patterns in shallow dimple configurations (h/D ≤ 0.1), including single cylindrical and spherical dimples, as well as single spanwise rows of dimples. The flow patterns, in-dimple separation zone extent, and bulk flow oscillation frequencies have been measured at low Reynolds number conditions. Three different single dimples and two single rows of dimples have been tested over a range of Reynolds numbers ReD of 3,170 to 23,590 including laminar and turbulent flow patterns downstream of a dimple. To visualize the fine flow features, five different colors of dye were injected through five cylindrical ports machined at locations upstream and inside the dimples. The measured results revealed unsteady and three-dimensional flow features inside and downstream of the dimple. The Reynolds number, dimple shape and the presence of adjacent dimples all play important roles in determining the nature of the flow pattern formation. Some preliminary conclusions regarding the laminar-turbulent flow transition after a dimple are presented.

Numerical Simulation of Three-Dimensional Unsteady Flow Field in the Cyclone

2013 ◽  
Vol 774-776 ◽  
pp. 258-261 ◽  
Author(s):  
Zong Rui Hao ◽  
Juan Xu ◽  
Hai Yan Bie ◽  
Zhong Hai Zhou
Keyword(s):  
Turbulent Flow ◽  
Collection Efficiency ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Flow Characteristics ◽  
Dust Particles ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Airflow Field ◽  
Swirling Strength

Large eddy simulation to describe the turbulent flow of airflow field was used to calculate the unsteady turbulent flow characteristics in the cyclone. It funded that the tangential velocity in the cyclone profile behaved like rankine vortex, with the downward semi-free vortex of the outer layer and the upward forced vortex. With the increasing import gas velocity, the swirling strength of the center increased which reduced collection efficiency by clouding the dust particles in the ash bucket to the center airflow.

Turbulent Flow Energy Budget Calculations in a Dump Combustor Model

2014 ◽  
Author(s):  
Saad Ahmed ◽  
Bharath Raghavan ◽  
Mohamed Gadalla
Keyword(s):  
Neural Networks ◽  
Turbulent Flow ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Energy Budgets ◽  
Feed Forward Neural Network ◽  
Flow Energy ◽  
Dump Combustor ◽  
Turbulent Statistics

Turbulent statistics and energy budgets were calculated for a swirling turbulent flow using Generalized Feed Forward Neural Network (GFFNN) in a dump combustor model. Knowledge of turbulent statistics and energy budgets of fluid flow inside a combustor model is very useful and essential for better and/or optimum designs of gas turbine combustors. Several experimental techniques utilizing two dimensional (2D) or three dimensional (3D) Laser Doppler Velocimetry (LDV) measurements provide only limited discrete information at given points; especially, for the cases of complex flows such as dump combustor swirling flows. For these flows, numerical interpolating schemes are unsuitable. Recently, neural networks proved to be viable means of expanding a finite set of experimental measurements in order to enhance the understanding of complex phenomenon. This investigation showed that artificial neural networks are suitable for the prediction of turbulent swirling flow characteristics in a model dump combustor. These techniques are proposed for better designs and/or optimum performance of dump combustors.

Design and optimization of bump (compression surface) for diverterless supersonic inlet

2021 ◽  
pp. 095441002110029
Author(s):  
Irsalan Arif ◽  
Hassan Iftikhar ◽  
Ali Javed
Keyword(s):  
Fitness Function ◽  
Supersonic Jet ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Least Square ◽  
Pressure Recovery ◽  
Design Parameters ◽  
Inlet System ◽  
Design And Optimization ◽  
Supersonic Inlet

In this article design and optimization scheme of a three-dimensional bump surface for a supersonic aircraft is presented. A baseline bump and inlet duct with forward cowl lip is initially modeled in accordance with an existing bump configuration on a supersonic jet aircraft. Various design parameters for bump surface of diverterless supersonic inlet systems are identified, and design space is established using sensitivity analysis to identify the uncertainty associated with each design parameter by the one-factor-at-a-time approach. Subsequently, the designed configurations are selected by performing a three-level design of experiments using the Box–Behnken method and the numerical simulations. Surrogate modeling is carried out by the least square regression method to identify the fitness function, and optimization is performed using genetic algorithm based on pressure recovery as the objective function. The resultant optimized bump configuration demonstrates significant improvement in pressure recovery and flow characteristics as compared to baseline configuration at both supersonic and subsonic flow conditions and at design and off-design conditions. The proposed design and optimization methodology can be applied for optimizing the bump surface design of any diverterless supersonic inlet system for maximizing the intake performance.

Sign in / Sign up

Export Citation Format

Share Document