A Wind Tunnel Study Of The Interaction Between Two Sailing Yachts

2013 ◽  
Author(s):  
P. J. Richards ◽  
D. J. Le Pelley ◽  
D. Jowett ◽  
J. Little ◽  
O. Detlefsen
Keyword(s):  
Wind Tunnel ◽  
Test Section ◽  
Force Measurement ◽  
Aerodynamic Force ◽  
Force Balance ◽  
The Other ◽  
Flow Disturbance ◽  
Negative Interference ◽  
Wind Tunnel Study

The interference between two yachts sailing in several conditions is investigated in the wind tunnel by using two similar yacht models, one of which is mounted on a force balance and the other moved around the test section. The yachts were configured to sail close-hauled upwind at 20° apparent wind angle, downwind under asymmetric spinnaker at 60° and downwind under symmetric spinnaker at 120° apparent wind angle. The regions of positive and negative interference are determined through aerodynamic force measurement and flow disturbance measurement, and the sources of these effects investigated.

A new method for force prediction in an accelerometer force balance system using support vector regression

2020 ◽  
Vol 42 (4) ◽  
pp. 880-889
Author(s):  
Sushmita Deka ◽  
Pallekonda Ramesh Babu ◽  
Maneswar Rahang
Keyword(s):  
Support Vector Regression ◽  
Force Measurement ◽  
Aerodynamic Force ◽  
Accurate Prediction ◽  
Force Balance ◽  
Support Vector ◽  
Inference System ◽  
Force Prediction ◽  
Balance System ◽  
Testing Data

The accurate prediction of force is very important in the present scenario of aerodynamic force measurement. The high accuracy of force prediction during calibration facilitates a better accuracy of force measurement in aerodynamic facilities like shock tunnels and wind tunnels. The present study describes the force prediction in an accelerometer force balance system using support vector regression (SVR). The comparison of SVR with the existing force prediction techniques namely, adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) has also been carried out. The accelerometer force balance used in the current experimentation consists of a tri-axial accelerometer to measure the response on an aluminium hemispherical model on the application of force. The impulse forces were applied along the axial, normal and azimuthal directions. The forces were predicted using the accelerations obtained from the tri-axial accelerometer. SVR method was able to predict the forces quite accurately as compared to ANFIS and ANN. However, SVR has the advantage over ANFIS and ANN in that it is independent of the magnitude of the training and testing data. It is capable of an accurate prediction of forces with any magnitude of training and testing data, unlike ANFIS and ANN.

Wind Tunnel Study on a Missile with Forward-Facing Cavity in Supersonic Flow

2014 ◽  
Vol 1016 ◽  
pp. 370-376
Author(s):  
Jiang Zhang ◽  
Xiao Jun Pan ◽  
Jin Gang Dong ◽  
Yong Ming Qin ◽  
Han Dong Ma
Keyword(s):  
Wind Tunnel ◽  
Total Pressure ◽  
Force Measurement ◽  
Cavity Flow ◽  
Bow Shock ◽  
Dynamic Force ◽  
Flow Conditions ◽  
Fluctuation Pressure ◽  
Wind Tunnel Study ◽  
Transonic Wind Tunnel

A forward-facing cavity will be composed of the components of a scramjet from inlet to combustion chamber which has a uncovered inlet before the separation of the booster. Longitudinal oscillations are generated within the cavity under some certain flow conditions. Strong oscillations may damage the components of the scramjet, or induce bow-shock oscillations which may cause unsteady loads on the missile and affect the performance of the aerodynamical characteristics. An experimental study of missile model with a scramjet was conducted in a transonic wind tunnel. The characteristics of cavity flow were researched by both the dynamic force measurement and the fluctuation pressure measurement. In the experiments the oscillations within the cavity and the bow-shock in front of the inlet interacted. The oscillations of cavity flow and bow-shock affected the fluctuation pressure and the aerodynamical characteristics of missile remarkably. The amplitude of axial force was higher than the normal force's. The RMS of the fluctuation pressure of some measured place inside the scramjet reached a quarter of the total pressure, and the amplitude of the fluctuation reached half of the total pressure. Those might threaten the safety of the structure of the scramjet.

scholarly journals Hypersonic Aerodynamic Force Balance Using Micromachined All-Fiber Fabry–Pérot Interferometric Strain Gauges

Micromachines ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 316 ◽  
Author(s):  
Huacheng Qiu ◽  
Fu Min ◽  
Yanguang Yang ◽  
Zengling Ran ◽  
Jinxin Duan
Keyword(s):  
Wind Tunnel ◽  
Aerodynamic Force ◽  
High Sensitivity ◽  
Force Balance ◽  
Strain Gauges ◽  
External Temperature ◽  
Thermal Output ◽  
Hypersonic Wind Tunnel ◽  
Wide Range ◽  
Fabry Perot

This paper presents high-sensitivity, micromachined all-fiber Fabry–Pérot interferometric (FFPI) strain gauges and their integration in a force balance for hypersonic aerodynamic measurements. The FFPI strain gauge has a short Fabry–Pérot cavity fabricated using an excimer laser etching process, and the deformation of the cavity is detected by a white-light optical phase demodulator. A three-component force balance, using the proposed FFPI gauges as sensing elements, was fabricated, calibrated, and experimentally evaluated. To reduce thermal output of the balance, a simple and effective self-temperature compensation solution, without external temperature sensors, is proposed and examined through both oven heating and wind tunnel runs. As a result of this approach, researchers are able to use the balance continuously throughout a wide range of temperatures. During preliminary testing in a hypersonic wind tunnel with a free stream Mach number of 12, the measurement accuracies of the balance were clearly improved after applying the temperature self-compensation.

Wind Tunnel Test on Wind-Induced Aerodynamic Force of Transmission Tower

2014 ◽  
Vol 578-579 ◽  
pp. 427-431
Author(s):  
Wen Shan Shan ◽  
Bo Li ◽  
Jing Bo Yang ◽  
Yang Liu
Keyword(s):  
Wind Tunnel ◽  
Power Transmission ◽  
Aerodynamic Force ◽  
Wind Tunnel Test ◽  
Force Balance ◽  
Test Results ◽  
Transmission Tower ◽  
Balance Test ◽  
Shape Coefficient ◽  
Wind Speeds

Wind-induced aerodynamic force is the important parameter for transmission tower design. Based on force balance test, the tower and cross arm of typical 500kV power transmission tower have been investigated in wind tunnel using three wind speeds considering Reynolds effect. The test results show that the shape coefficient keeps the same at different wind speed, which means that Reynolds effect on transmission tower can be ignored. Then, the shape coefficients of tower and cross arm are provided.

Extremely Gusty Winds from a Viewpoint of Aerodynamic Force

2020 ◽  
Author(s):  
Junji Maeda ◽  
Takashi Takeuchi ◽  
Eriko Tomokiyo ◽  
Yukio Tamura
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Rise Time ◽  
Aerodynamic Force ◽  
Step Function ◽  
Object Size ◽  
Aerodynamic Forces ◽  
Wind Force ◽  
Wind Observation

To quantitatively investigate a gusty wind from the viewpoint of aerodynamic forces, a wind tunnel that can control the rise time of a step-function-like gust was devised and utilized. When the non-dimensional rise time, which is calculated using the rise time of the gusty wind, the wind speed, and the size of an object, is less than a certain value, the wind force is greater than under the corresponding steady wind. Therefore, this wind force is called the “overshoot wind force” for objects the size of orbital vehicles in an actual wind observation. The finding of the overshoot wind force requires a condition of the wind speed recording specification and depends on the object size and the gusty wind speed.

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