scholarly journals Sail Aerodynamics: On-Water Pressure Measurements on a Downwind Sail

2012 ◽  
Vol 56 (04) ◽  
pp. 197-206
Author(s):  
Ignazio Maria Viola ◽  
Richard G. J. Flay
Keyword(s):  
Wind Tunnel ◽  
Pressure Distribution ◽  
Delta Wing ◽  
Water Pressure ◽  
Pressure Measurements ◽  
Dynamic Effects ◽  
Wind Tunnel Tests ◽  
Pressure Distributions ◽  
Similarities And Differences

Pressures on three horizontal sections of a downwind sail were measured for several wind directions and sail trims. The pressure distributions were compared with wind tunnel tests; similarities and differences were found, the latter as a result of the dynamic effects, which were not modeled in the wind tunnel. A pressure distribution at the head of the spinnaker resembling that from a delta wing was measured at an apparent wind angle of 120°.

Pressure Distributions on Sails Investigated Using Three Methods: On-Water Measurements, Wind-Tunnel Measurements, and Computational Fluid Dynamics

2011 ◽  
Author(s):  
Ignazio Maria Viola ◽  
Richard G. J. Flay
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Full Scale ◽  
Navier Stokes ◽  
Pressure Measurements ◽  
Wind Tunnel Tests ◽  
Pressure Distributions ◽  
Unstable Environment ◽  
Full Scale Tests ◽  
Good Agreement

The main results of a two-year project aimed at comparing full-scale tests, wind tunnel tests, and numerical analysis predictions are presented. Pressure measurements were obtained from both full-scale tests and wind-tunnel tests, in upwind and downwind conditions. The upwind wind tunnel test condition was modelled using a Vortex Lattice code, while the downwind wind-tunnel test was modelled using a Navier-Stokes code. The pressures obtained from the three different methods are compared on three horizontal sections of the headsail, mainsail, and asymmetric spinnaker. In general the pressures from the three experiments showed good agreement. In particular, very good agreement was obtained between the numerical computations and the wind tunnel test results. Conversely, the results from the downwind full-scale pressure measurements showed less similarity due to a slightly tightened trim being used for the spinnaker in the on-water tests. Full-scale tests allow the action of unsteadiness due to the wind, wave and yacht movements to affect the results. This unstable environment caused the asymmetric spinnaker to move around, and a tightened trim was required to prevent the spinnaker from collapsing.

Effect of Added Mass on Wind-Induced Vibration of a Circular Flat Membrane by Wind Tunnel Tests

2018 ◽  
Vol 18 (12) ◽  
pp. 1850156
Author(s):  
Yi Zhou ◽  
Yuanqi Li ◽  
Akihito Yoshida
Keyword(s):  
Wind Tunnel ◽  
Dynamic Analysis ◽  
Pressure Distribution ◽  
Added Mass ◽  
Wind Pressure ◽  
Induced Response ◽  
Wind Tunnel Tests ◽  
Rigid Model ◽  
Flat Membrane ◽  
Wind Induced Vibration

Flexible roof structures, such as membranes, are sensitive to wind action due to their flexibility and light weight. Previously, the effect of added mass on the vibration frequency of membrane structures has been experimentally tested. However, the effect of added mass on wind-induced vibration remains unclear. The purpose of this paper is to investigate the effect of added mass on the wind-induced vibration of a circular flat membrane based on wind tunnel tests. First, wind tunnel tests were conducted to obtain wind pressure distribution from the rigid model and wind-induced vibration from the aeroelastic model of a circular flat membrane. Secondly, a dynamic finite element analysis for the proposed added mass model was conducted to obtain the wind-induced vibration of the membrane structure. Then, with the wind pressure distribution obtained from the rigid model tests, dynamic analysis was conducted either with or without consideration of the effect of added mass. According to the dynamic analysis results and the wind tunnel test results, it is clear that considering the effect of added mass in dynamic analysis can significantly improve the accuracy of a wind-induced response. Such an effect is more significant at the windward than the central zone. The inclusion of added mass can result in a larger displacement response as wind velocity increases but a smaller response as the prestress level increases.

AERODYNAMIC FORCE DEDUCTION ON YACHT SAILS USING PRESSURE AND SHAPE MEASUREMENTS IN REAL TIME

2015 ◽  
Vol 157 (B2) ◽  
Author(s):  
D Le Pelley ◽  
D Morris ◽  
P Richards ◽  
D Motta
Keyword(s):  
Wind Tunnel ◽  
Pressure Distribution ◽  
Real Time ◽  
Aerodynamic Force ◽  
Full Scale ◽  
Force Distribution ◽  
Wind Tunnel Tests ◽  
Force Components ◽  
Full Scale Testing

This paper describes a method of deducing aerodynamic force components produced by individual sails. This is achieved by measuring the pressure distribution at a number of discrete locations over the sail and extrapolating these measurements into a distribution across the entire sail surface. The sail shape is measured using the camera-based VSPARS system and the force distribution over the sail surface is then determined. Wind tunnel tests have been conducted to validate the accuracy of the model. Full scale testing has been undertaken to investigate how aerodynamic effects of trimming sails affect yacht performance.

scholarly journals Characteristics of Wind Load on Spatial Structures with Typical Shapes due to Aerodynamic Geometrical Parameters and Terrain Type

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Yi Zhou ◽  
Yuanqi Li ◽  
Yingying Zhang ◽  
Akihito Yoshida
Keyword(s):  
Wind Tunnel ◽  
Pressure Distribution ◽  
Strong Dependence ◽  
Wind Load ◽  
Wind Pressure ◽  
Geometrical Parameters ◽  
Spatial Structures ◽  
Wind Tunnel Tests ◽  
Terrain Type ◽  
Design Optimum

The characteristics of wind load on large-span roofs are complicated by their unique geometrical configurations and strong dependence on aerodynamic geometrical parameters and terrain type. However, there is rarely comprehensive research for characteristics of wind load on spatial structures due to aerodynamic geometrical parameters of roofs and terrain type. In this study, first, the effects of geometrical parameters of roofs and terrain type on the wind pressure distribution based on the data obtained from the existing wind tunnel tests were summarized. Then, the wind loads of full-scale structures were predicted by CFD, and the efficiency of numerical results was further verified by the available wind tunnel tests on spatial structures. Finally, with comparative analyses of the wind pressure distribution of the roofs predicted by CFD under different cases, the effects of shape ratios, especially rise-span ratio, height-span ratio, length-span ratio, and so on, and terrain type on the wind pressure field of typical spatial structures were presented. It can be beneficial to wind-resistant design of structures and can be provided as reference for aerodynamic design optimum of span spatial structures.

Blade Curve Influences on Performance of Savonius Rotors: Experimental and Numerical

2010 ◽  
Author(s):  
Ali Kianifar ◽  
Morteza Anbarsooz ◽  
Mohammad Javadi
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Wind Tunnel ◽  
Flow Field ◽  
Pressure Distribution ◽  
Power Coefficient ◽  
Blade Surface ◽  
Wind Tunnel Tests ◽  
Savonius Rotor ◽  
Circular Curves

In this study, the effect of blade curve on the power coefficient of a Savonius rotor is investigated by means of numerical simulation and wind tunnel tests. The tests were conducted on six rotors with identical dimensions but different blade curves, and the influences of blade curve and Reynolds number were studied. Followed by a simulation of the flow field around rotors with identical semi-circular curves and different overlaps, torque was calculated using pressure distribution on the blade surface, and the effect of Reynolds number and blade curve were studied on torque as well. Results indicate that changing the blade curve affects the power coefficient and torque by causing different drag coefficients. Also the rotor that yields the highest power coefficient and torque in one revolution compared with other rotors is highlighted.

scholarly journals Use of Supersonic Cascades Made of Blades of Simple Geometric Shapes for Cascade Wind Tunnel Performance Evaluation

1970 ◽  
Author(s):  
J. Fabri ◽  
J. Paulon ◽  
G. Janssens
Keyword(s):  
Performance Evaluation ◽  
Wind Tunnel ◽  
Shock Waves ◽  
Flow Patterns ◽  
Compressor Blade ◽  
Geometric Shape ◽  
Compressor Cascade ◽  
Wind Tunnel Tests ◽  
Pressure Distributions ◽  
Blade Cascade

Use of blades of simple geometric shape for supersonic compressor cascade tests gives easy means to check the validity of wind tunnel tests, since comparison of experimental and theoretical shock and flow patterns as well as pressure distributions is simplified due to the fact that there exists only a limited number of discrete shock waves or expansion fans. A supersonic compressor blade cascade wind tunnel performances are evaluated according to this technique.

Variable Reynolds Number Experimental Study on Aerodynamic Characteristic of Supercritical Airfoil RAE2822

2013 ◽  
Vol 420 ◽  
pp. 42-46
Author(s):  
Na Wang ◽  
Chao Gao
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Wind Tunnel ◽  
Pressure Distribution ◽  
Pressure Coefficient ◽  
Lower Surface ◽  
Number Range ◽  
Moment Coefficient ◽  
Pressure Distributions ◽  
The Moment

An experimental study of pressure distributions over RAE2822 airfoil in the two-dimensional test section 0.8×0.4 meter of a transonic wind tunnel which is the first pressruized continuous wind tunnel in China is presented. This paper in order to further study the influence of the dynamic of continuous changes Reynolds number at Mach number is 0.66 and 0.80, and the attack angle is from-2 degree to 10 degree, and especially the Reynolds number range from3.0×106to 12×106. The study is focalized on the subsonic range of flow conditions with separation and shock wave in the boundary layer. The influence of pressure distribution and pressure coefficient and moment coefficient caused by Reynolds number increasing are analyzed and discussed. The conclusions showed that the pressure distribution of the lower surface of the airfoil get the influence of the Reynolds number is negligible. The Reynolds number impact on the pressure distribution is faintness at Ma=0.66. Reynolds number increases affect the airfoil central and trailing edge pressure. As the Reynolds number increases, the CL curve move and the gradient increasing. The moment coefficient decreased as the Reynolds number increasing. The CL curve with Cd curve moves left as Reynolds number increasing.

Impact of the trailing edge shape of a downstream dummy vehicle on train aerodynamics subjected to crosswind

2020 ◽  
pp. 095440972091503 ◽  
Author(s):  
Xiaoshuai Huo ◽  
Tanghong Liu ◽  
Miao Yu ◽  
Zhengwei Chen ◽  
Zijian Guo ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Detached Eddy Simulation ◽  
Trailing Edge ◽  
Wind Tunnel Tests ◽  
Eddy Simulation ◽  
Pressure Distributions ◽  
Delayed Detached Eddy Simulation ◽  
Yaw Angle ◽  
Train Aerodynamics ◽  
The Impact

Wind tunnel tests for trains under large yaw angles are usually limited due to the width of the wind tunnel. Therefore, the leading car and a downstream dummy vehicle model are often employed instead of a real train, but there are no clear regulations regarding the shape of the end of the dummy vehicle. This paper studied the impact of the trailing edge shape of the downstream dummy vehicle on train aerodynamics subjected to crosswind based on the shear-stress-transport k-ω turbulence model of the delayed detached eddy simulation. Three types of end shapes, namely the rectangular end shape, the arc end shape, and the streamlined end shape were chosen for comparison, and the simulation results of the three-car-group train were selected as the benchmark. First, the reliability of the numerical method was validated by wind tunnel tests. Then, the aerodynamic coefficients under yaw angles of 0°–60° and the surface pressure distributions and flow structures around the train under the yaw angle of 60° of the head cars with different end shapes were compared and analyzed.

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