scholarly journals experimental investigation on stall flutter over a vertically mounted rigid finite wing

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Renan Francisco Soares ◽  
Ilyas Karasu ◽  
Bharath Ganapathisubramani
Keyword(s):  
Experimental Investigation ◽  
Wind Tunnel ◽  
Position Tracking ◽  
Experimental Campaign ◽  
Successful Approach ◽  
Box Method ◽  
Stall Flutter ◽  
Finite Wing ◽  
Long Endurance ◽  
Rigid Wing

As stall flutter has relevant engineering implications, such as in blades of wind turbine and HALE (highaltitude long-endurance aircraft). This work presents the experimental investigation of rigid wing setup in a closed-circuit wind tunnel having 2.1 m × 1.5 m test section. The experimental campaign reached stable and symmetrical LCO within the freestream range from 9 m/s up to 14 m/s (1.69 × 105 < Re < 2.63 × 105 ). Two techniques were used for position tracking: one mechatronic and one image-based. The latter used ‘shakethe-box’ method applied to a body, which has proven a successful approach as a non-intrusive tool.

A Theoretical Investigation of the Maximum-lift Coefficient

1935 ◽  
Vol 39 (295) ◽  
pp. 619-632
Author(s):  
TH. Von karman ◽  
Clark B. Millikan
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Wind Tunnel ◽  
Theoretical Investigation ◽  
Lift Coefficient ◽  
Wind Tunnels ◽  
California Institute ◽  
California Institute Of Technology ◽  
Junior Author ◽  
Institute Of Technology

The problem of the maximum lift of airfoils has concerned the authors greatly since there were first discovered in the spring of 1932 serious discrepancies in this characteristic between results obtained in the wind tunnel of the Guggenheim Aeronautics Laboratory at the California Institute of Technology (GALCIT) and those reported from certain other wind tunnels. An elaborate experimental investigation by the junior author and A. L. Klein indicated that the value of CLmax for a given airfoil was strongly affected both by Reynolds number and by the degree of turbulence in the tunnel wind stream.

Experimental Investigation of a Drafting Cyclist in Cross-Wind

2017 ◽  
Author(s):  
Ivaylo Nedyalkov ◽  
Adam Lovell ◽  
Alec Cunningham
Keyword(s):  
Experimental Investigation ◽  
Wind Tunnel ◽  
3D Model ◽  
Noticeable Effect ◽  
Side Force ◽  
Scale Models ◽  
Competitive Cyclists

Drafting is commonly utilized in cycling, particularly during competitions. According to the literature, in a racing environment, the riders can expend 90% of their energy on overcoming drag, and can save about 30% of their energy by riding behind another rider in the absence of cross-wind. In the presence of a strong cross-wind, competitive cyclists form echelons by placing themselves about halfway behind each other, while being slightly offset sideways. Although forming an echelon is a common practice, the formation has not been sufficiently studied in the literature. To address this, the drag and side forces on a model cyclist were studied experimentally. A simplified 3D model was built based on the outline of a competitive cyclist. Two 1:11 scale models were rapid-prototyped and tested in a wind tunnel. The drafting effects on a cyclist were investigated for different yaw angles — the angles of the apparent wind with respect to the direction of cyclist motion. The effects of wind-stream-wise position and wind-off-stream-wise position were studied for each angle by measuring the drag and side-force on a model placed in the wake of another identical model. The results suggest that there is a significant decrease in both drag and side force when a cyclist is riding in the wake of another cyclist. Although a smaller wind-stream-wise offset generally results in smaller forces, this effect is not significant for most configurations. The offset in the wind-off-stream-wise direction has a noticeable effect on the forces — no off-stream-wise offset results in the lowest drag and side force, except for low yaw angles at which it may be beneficial for the drafting cyclist to be slightly forward with respect to the in-line (no offset) position.

Dynamic Unstructured Grids Method with Applications to Unsteady Flows Involving Moving Boundaries

2015 ◽  
Vol 757 ◽  
pp. 87-91
Author(s):  
Jun Li Wang ◽  
Dong Sheng Zhang
Keyword(s):  
Unstructured Grids ◽  
Boundary Effect ◽  
Analogy Method ◽  
Torsion Oscillation ◽  
Spring Method ◽  
Euler Solver ◽  
Long Endurance ◽  
Good Agreement ◽  
Rigid Wing

Spring analogy method for dynamic unstructured grids is studied. The stiffness of the springs in the vertex spring method is analyzed. Improvements considering squashing spring effect and boundary effect are developed to the standard method. Applications of the improved spring analogy method to dynamic grids generation show that the new method greatly improves the deforming ability and the quality of the grids. This improved unstructured dynamic mesh method, coupled with ALE Euler solver, is then applied to simulate unsteady transonic flow about harmonious oscillation of rigid wing and bend-torsion oscillation of high-aspect ratio sweepback wing of High-Altitude-Long-Endurance Unmanned Aerial Vehicles; computational results are in good agreement with those of other literatures and experiments

Experimental Investigation of Periodic Wind Gust Generated in a Low Speed Wind Tunnel

2014 ◽  
Author(s):  
Parag Deshpande ◽  
Shweta Singh ◽  
Prasobh Narayanan ◽  
Dinesh Babu ◽  
Balamurali Sundaramoorthy
Keyword(s):  
Experimental Investigation ◽  
Wind Tunnel ◽  
Wind Gust ◽  
Low Speed ◽  
Low Speed Wind Tunnel

scholarly journals Experimental Investigation of Wind Turbine Wakes in the Wind Tunnel

2013 ◽  
Vol 35 ◽  
pp. 285-296 ◽  
Author(s):  
Heiner Schümann ◽  
Fabio Pierella ◽  
Lars Sætran
Keyword(s):  
Experimental Investigation ◽  
Wind Tunnel ◽  
Wind Turbine

Experimental investigation of aerodynamic vibrations of solar wing system

2018 ◽  
Vol 21 (15) ◽  
pp. 2217-2226 ◽  
Author(s):  
YC Kim ◽  
Y Tamura ◽  
A Yoshida ◽  
T Ito ◽  
W Shan ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Experimental Investigation ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Solar Panels ◽  
Boundary Layer Flows ◽  
Turbulence Flow ◽  
Aeroelastic Model ◽  
Mean Wind Speed ◽  
The Mean

The general characteristics of aerodynamic vibrations of a solar wing system were investigated through wind tunnel tests using an aeroelastic model under four oncoming flows. In total, 12 solar panels were suspended by cables and orientated horizontally. Distances between panels were set constant. Tests showed that the fluctuating displacement increases proportionally to the square of the mean wind speed for all wind directions in boundary-layer flows. Larger fluctuating displacements were found for boundary-layer flows with larger power-law indices. Under low-turbulence flow, the fluctuating displacement increased proportionally to the square of the mean wind speed for wind directions between 0° and 30°, but an instability vibration was observed at high mean wind speed for wind directions larger than 40°. And when the wind direction was larger than 60°, a limited vibration was observed at low mean wind speed and the instability vibration was also observed at high mean wind speed. Fluctuating displacements under grid-generated flow showed a similar trend to that of the boundary-layer flows, although the values became much smaller.

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