Surface flow patterns on an ogive-cylinder at incidence

AIAA Journal ◽  
1992 ◽  
Vol 30 (1) ◽  
pp. 272-274 ◽  
Author(s):  
David Degani ◽  
Murray Tobak ◽  
G. G. Zilliac
Keyword(s):  
Flow Patterns ◽  
Surface Flow

Surface Flow Patterns on Blunt Bodies

1993 ◽  
pp. 213-221 ◽  
Author(s):  
N. Nishikawa ◽  
T. Ishide ◽  
S. Kida
Keyword(s):  
Flow Patterns ◽  
Surface Flow ◽  
Blunt Bodies

scholarly journals Air Pollution Flow Patterns in the Mexico City Region

Climate ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 128
Author(s):  
Alejandro Salcido ◽  
Susana Carreón-Sierra ◽  
Ana-Teresa Celada-Murillo
Keyword(s):  
Air Pollution ◽  
Cluster Analysis ◽  
Mexico City ◽  
Air Pollutants ◽  
Flow Patterns ◽  
Surface Flow ◽  
Flow State ◽  
City Region ◽  
Wind Circulation ◽  
Flow Vector

According to the Mexico City Emissions Inventory, mobile sources are responsible for approximately 86% of nitrogen oxide emissions in this region, and correspond to a NOx emission of 51 and 58 kilotons per year in Mexico City and the State of Mexico, respectively. Ozone levels in this region are often high and persist as one of the main problems of air pollution. Identifying the main scenarios for the transport and dispersion of air pollutants requires the knowledge of their flow patterns. This work examines the surface flow patterns of air pollutants (NO2, O3, SO2, and PM10) in the area of Mexico City (a region with strong orographic influences) over the period 2001–2010. The flow condition of a pollutant depends on the spatial distribution of its concentration and the mode of wind circulation in the region. We achieved the identification and characterization of the pollutant flow patterns through the exploitation of the 1-hour average values of the pollutant concentrations and wind data provided by the atmospheric monitoring network of Mexico City and the application of the k-means method of cluster analysis. The data objects for the cluster analysis were obtained by modeling Mexico City as a 4-cell spatial domain and describing, for each pollutant, the flow state in a cell by the spatial averages of the horizontal pollutant flow vector and its gradients (the divergence and curl of the flow vector). We identified seven patterns for wind circulation and nine patterns for each of NO2, O3, PM10, and SO2 pollutant flows. Their seasonal and annual average intensities and probabilities of occurrence were estimated.

Flow Field Study and Structure Optimization of Pelton Tubine Bucket

2013 ◽  
Vol 655-657 ◽  
pp. 144-148
Author(s):  
Xia Ma ◽  
Wu Gui Hua ◽  
Jie Li ◽  
Gang Li
Keyword(s):  
Free Surface ◽  
Homogeneous Model ◽  
Structure Optimization ◽  
Free Surface Flow ◽  
Flow Patterns ◽  
Surface Flow ◽  
Two Phase ◽  
Pelton Turbine ◽  
Flow Visualizations ◽  
Turbine Model

The aim of the paper is to present the results of investigations conducted on the free surface flow in a Pelton turbine model bucket. Unsteady numerical simulations, based on the two-phase homogeneous model, are performed together with flow visualizations. The results obtained allow defining five distinct zones in the bucket from the flow patterns. The flow patterns in the buckets are analyzed from the results. An investigation of the momentum transfer between the water particles and the bucket is performed, showing the regions of the bucket surface that contribute the most to the torque. The study is also conducted for the backside of the bucket, evidencing a probable Coanda interaction between the bucket cutout area and the Water jet.

scholarly journals Flow in a Pelton Turbine Bucket: Numerical and Experimental Investigations

2005 ◽  
Vol 128 (2) ◽  
pp. 350-358 ◽  
Author(s):  
Alexandre Perrig ◽  
François Avellan ◽  
Jean-Louis Kueny ◽  
Mohamed Farhat ◽  
Etienne Parkinson
Keyword(s):  
Homogeneous Model ◽  
Free Surface Flow ◽  
Flow Patterns ◽  
Surface Flow ◽  
Experimental Investigations ◽  
Pressure Measurements ◽  
Two Phase ◽  
Pelton Turbine ◽  
Flow Visualizations ◽  
Turbine Bucket

The aim of the paper is to present the results of investigations conducted on the free surface flow in a Pelton turbine model bucket. Unsteady numerical simulations, based on the two-phase homogeneous model, are performed together with wall pressure measurements and flow visualizations. The results obtained allow defining five distinct zones in the bucket from the flow patterns and the pressure signal shapes. The results provided by the numerical simulation are compared for each zone. The flow patterns in the buckets are analyzed from the results. An investigation of the momentum transfer between the water particles and the bucket is performed, showing the regions of the bucket surface that contribute the most to the torque. The study is also conducted for the backside of the bucket, evidencing a probable Coanda interaction between the bucket cutout area and the water jet.

A Flow Visualization Study of Axial Turbine Tip Desensitization by Coolant Injection From a Tip Trench

2004 ◽  
Author(s):  
Nikhil M. Rao ◽  
Cengiz Camci
Keyword(s):  
Flow Visualization ◽  
Flow Patterns ◽  
Surface Flow ◽  
Leakage Flow ◽  
Pressure Side ◽  
Suction Surface ◽  
Blade Height ◽  
Side Edge ◽  
Coolant Injection ◽  
Gap Height

The effect of coolant injection from a tip trench was investigated in a large-scale rotating turbine rig. Coolant is injected into the tip gap from discrete injection holes, located in a tip trench and directed towards the pressure-side. Surface flow patterns are visualized by a mixture of oil and paint. The mixture is applied on the blade pressure-side and allowed to seep onto the tip platform. Injection rates of 0.4%, 0.5%, 0.6%, and 0.7%, at a gap height of 1.40% blade height were investigated. Flow patterns for a gap height of 0.72% blade height are compared to the larger clearance gap. The flow visualization technique successfully identifies flow features like pressure-side edge separation, and reattachment and recirculation on the tip surface. The location of the reattachment line from the pressure-side edge varies little along the length of the blade and occurs at about two gap heights from the pressure-side edge. At the large gap height the tip gap flow is fully separated over the last 5% of the blade axial chord. Surface oil flow lines are directed almost normal to the camberline along most of the tip surface. Flow patterns with injection indicate that the ejected coolant effectively blocks the leakage flow. The coolant jets are turned towards the blade suction-side and appear to form a film on the tip surface. Some of the visualization material is carried by the leakage flow into the passage and is deposited on the blade suction surface, thereby giving an indication of the inception and growth of the leakage vortex. Suction surface patterns with injection indicate that leakage flow may be entering the adjacent passage at multiple locations.

0522 Analysis of Free Surface Flow Patterns of Undershot Cross-Flow Water Turbines Used by Advanced Equipment

2015 ◽  
Vol 2015 (0) ◽  
pp. _0522-1_-_0522-4_
Author(s):  
Yuichiro YAHAGI ◽  
Yasuyuki NISHI ◽  
Terumi INAGAKI ◽  
Yanrong LI ◽  
Kentaro HATANO ◽  
...  
Keyword(s):  
Free Surface ◽  
Cross Flow ◽  
Free Surface Flow ◽  
Flow Patterns ◽  
Surface Flow ◽  
Water Turbines

LES Study of the Influence of a Train-Nose Shape on the Flow Structures Under Cross-Wind Conditions

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
Hassan Hemida ◽  
Siniša Krajnović
Keyword(s):  
High Speed ◽  
Pressure Coefficient ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Surface Flow ◽  
Flow Structures ◽  
Local Pressure ◽  
Freestream Velocity ◽  
Train Simulation ◽  
Long Nose

Cross-wind flows around two simplified high-speed trains with different nose shapes are studied using large-eddy simulation (LES) with the standard Smagorinsky model. The Reynolds number is 3×105 based on the height of the train and the freestream velocity. The cross section and the length of the two train models are identical while one model has a nose length twice that of the other. The three-dimensional effects of the nose on the flow structures in the wake and on the aerodynamic quantities such as lift and side force coefficients, flow patterns, local pressure coefficient, and wake frequencies are investigated. The short-nose train simulation shows highly unsteady and three-dimensional flow around the nose yielding more vortex structures in the wake. These structures result in a surface flow that differs from that in the long-nose train flow. They also influence the dominating frequencies that arise due to the shear-layer instabilities. Prediction of vortex shedding, flow patterns in the train surface, and time-averaged pressure distribution obtained from the long-nose train simulation are in good agreement with the available experimental data.

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