Straight Wing Research Articles

Flow Analysis and Performance of Straight Wing Vertical Axis Wind Turbine (4)

Flow Analysis and Performance of Straight Wing Vertical Axis Wind Turbine (4)

A Bendable Load Stiffened Wing for Small UAVs

A bendable load stiffened wing, developed at the University of Florida, has the ability to load stiffen in the positive flight load direction while remaining compliant in the opposite direction, enabling UAV storage inside smaller packing volumes. The wing employs an under-cambered airfoil with a swept planform providing dissimilar stiffness in the flight load and the folding direction. A comparative experimental study is performed using two wing geometries; straight camber and swept camber. The load stiffening ability is tested by performing three point bend tests while monitoring the wing root airfoil shape change using a visual image correlation technique. For the wing utilizing a swept camber design, increase in the root airfoil camber with increased loading resulted in a load stiffening structure. Swept camber wing showed a higher load carrying capacity (7 g's load factor) over a straight camber wing design (2 g's load factor), still maintaining the compliant nature in the folding direction. Long term storage induced creep deformations are small in both of the wing geometries. By increasing the wing stiffness, sweepback helps in reducing spanwise residual creep strain. Wind tunnel tests at Re = 7×104 of both the straight camber and the swept camber wing show similar L/D ratios. The sweepback helps in improving the static stability of the wing. Thus the bendable load stiffened wing has a clear advantage of offering stiffness improvement and reducing storage induced creep residual strains while maintaining the aerodynamic efficiency and improving the static stability of the wing.

Flow field around the front wing of Formula One racing car model: BAR Honda 003 and MP4-21 under ground effect

In Formula One racing, the front wing of a Formula One race car is crucial in generating downforce. Few types of front wings were introduced throughout the years. Two of them were the straight wing and the curved (U-shaped) wing. The difference in performance and flow structures between the two types of wings were experimentally investigated using scaled models with six-axes load cell, dye flow visualisation and PIV. Besides that, actual scaled wing model on track condition with moving ground was looked into using computational fluid dynamics (CFD). The effect of ground clearance on the generation of downforce and drag for both wings were studied. In general, the straight wing performs better than the curved wing with larger downforce generation with a greater penalty in drag.

A106 垂直軸型風車の性能予測と流れの可視化に関する研究(OS2 再生可能エネルギー・マイクログリッド),動力エネルギーシステム部門20周年,次の20年への新展開)

A106 垂直軸型風車の性能予測と流れの可視化に関する研究(OS2 再生可能エネルギー・マイクログリッド),動力エネルギーシステム部門20周年,次の20年への新展開)

垂直軸型風車の性能予測と流れの可視化に関する研究(<特集>第14回動力・エネルギー技術シンポジウム)

Researches about the aerodynamics of wind turbine with straight wing vertical axis (SW-VAWT) are very limited, in spite of a number of advantages such as low dependence on wind direction variation and easy constructible straight blades. For these reasons, we are researching the lift type SW-VAWT for many years. The elucidation of the behavior of the flow inside and neighborhood of the wind turbine during the rotation is very important because of the performance improvement of the vertical axis wind turbine. This research examined to the velocity characters around a SW-VAWT by using the numerical simulation technique and the precision of the prediction technique was confirmed as this result. Furthermore, we estimated flow behavior during the wind turbine rotation by using this numerical simulation technique, and evaluated the flow around the wind turbine. This paper presents outline and results of these calculation and evaluations.

市街地用直線翼垂直軸風力発電機のフィールド実験に基づく挙動と出力性能に関する研究(<特集>第14回動力・エネルギー技術シンポジウム)

市街地用直線翼垂直軸風力発電機のフィールド実験に基づく挙動と出力性能に関する研究(<特集>第14回動力・エネルギー技術シンポジウム)

S0503-4-4 フィールド試験による直線翼縦軸風車の性能評価([S0503-4]自然の流体エネルギー利用技術(4))

In the current study, we propose a set of control scheme for field test of the straight wing vertical axis wind turbine, constructed by our group. The control scheme has two modes: The first mode is the control to keep the tip speed ratio to constant value in order to obtain highest power coefficient. For the purpose, variable load to the generator was used. The second mode is the control system of the disk brake, which is activated when the wind is strong, in order to avoid destruction by over rotation. The authors have established the control system for these purposes, and now filed test can be carried out in automatic operation.

A105 市街地用直線翼垂直軸風力発電機のフィールド実験に基づく挙動と出力性能に関する研究(風力システムの制御・改善・評価,OS2 自然エネルギー)

A105 市街地用直線翼垂直軸風力発電機のフィールド実験に基づく挙動と出力性能に関する研究(風力システムの制御・改善・評価,OS2 自然エネルギー)

A Study on Flow Analysis and Performance of Straight Wing Vertical Axis Wind Turbine

A Study on Flow Analysis and Performance of Straight Wing Vertical Axis Wind Turbine

A109 垂直軸型風車の性能予測と流れの可視化に関する研究(垂直軸方向風車の展開・改善・普及,OS2 自然エネルギー)

A109 垂直軸型風車の性能予測と流れの可視化に関する研究(垂直軸方向風車の展開・改善・普及,OS2 自然エネルギー)

J0503-4-1 直線翼縦軸風車のフィールド試験環境の構築(風力発電(4))

J0503-4-1 直線翼縦軸風車のフィールド試験環境の構築(風力発電(4))

On the patterns of wing cracks along an outcrop scale flaw: A numerical modeling approach using complementarity

The 2D Displacement Discontinuity Method (DDM) is combined with a complementarity algorithm to model the quasi‐static formation and patterns of wing cracks that emanate from regions of stress concentration along a sliding frictional flaw in an otherwise homogeneous and isotropic elastic material. Because stress states and geometry change with sliding on the flaw and wing crack propagation, one cannot specify the boundary conditions a priori. Under these circumstances complementarity is superior to other well‐known contact algorithms. We focus on meter scale phenomena where mineralogical heterogeneity (common to centimeter‐scale laboratory samples) and 3D geometry (common to kilometer‐scale crustal structures) reasonably can be ignored. Analytical solutions to the elastic boundary value problem of the closed sliding flaw include those that assume no friction, uniform friction, and a cohesive end zone (CEZ), and those that assume infinitesimal or straight wing cracks. Here we generalize the problem to consider linearly varying friction in the CEZ and curved wing cracks, and we allow the sliding flaw to open when mechanical interaction with the wing crack dictates that it should. Trace lengths of 135 strike‐slip faults in sandstone are linearly related to wing crack lengths ranging from 0.16 to 72 m and correspond to a range of remote principal stress ratios: 0.06 ≤σ2/σ1≤ 0.2. Opening displacement profiles of wing cracks from the numerical model can be significantly different from analytical solutions. These solutions may produce significant errors in stable crack length for curved propagation paths. The smeared out stress concentration in the CEZ and the heterogeneity in strength of rock suggest that multiple wing cracks may form in one slip event. The mechanical interactions of these cracks leads to kink angles that increase with distance from the flaw tip, a relationship commonly observed in nature.

Influence of Wing Section and Wing Setting Angle on the Starting Performance of a Darrieus Wind Turbine

In this study, the improvement of the starting performance of a Darrieus wind turbine with straight wings was investigated. The numerical simulation on the starting torque generated in the stationary Darrieus wind turbine was executed. The parameters used for the numerical simulation are wing section shape and wing setting angle. The wing sections tried were NACA0018, NACA4418 (camber inside), and NACA4418 (camber outside). The following conclusions were obtained in this study. In three kinds of wing sections in which wing setting angle is set in 0 degrees, NACA0018 performs the highest minimum starting torque. In case that the setting angle of NACA0018 is set in -5 degrees, the starting performance improves more than the setting angle 0 degrees.

21010 直線翼垂直軸風車用翼型の性能と風車効率に関する研究(流体工学(1),一般講演,学術講演)

The research of the optimum wing for the purpose of the performance improvement of straight wing vertical axis wind turbine in the windmill was carried out. In practical Reynolds number region of the windmill, wind tunnel experiment of the NACA system symmetric airfoil of various thicknesses was carried out. The experiment was carried out using the wing with several kinds wing tip, and the method for measuring three components of force at the good accuracy was examined. And, the windmill efficiency was calculated using the measured airfoil performance value. As the result, the effect of airfoil performance on the wind turbine performance was clarified.

D106 直線翼垂直軸風車の研究(風車性能2,OS-2 自然エネルギー(1),一般講演,地球温暖化防止と動力エネルギー技術)

In this paper we will present some novel results of our research and development in the filed of wind energy utilization. Our effort in this filed is mainly concentrated to the conceptual design of optimum airfoil sections for the blade of straight wing non-articulated vertical axis wind turbine which undergo cross wind motion. This concept was embodied in the design of a family of airfoil sections designated as Tokai Wind Turbine (TWT) sections and a series of wind tunnel testing was conducted to confirm its desired aerodynamic characteristics. Then, we designed an experimental straight wing non-articulated vertical axis wind turbine system with straight blades to evaluate system performance and structural analysis results, and furthermore to collect operating experiences under real, fluctuating wind conditions. We are now working for evaluating operational feasibility of five sets different straight wing non-articulated vertical axis wind turbines system, which are partially in service as pilot plants of regional energy development.

A Study on the Matching between the Straight Wing Non-articulated Vertical Axis Wind Turbine and the New Wind Turbine Generator

A Study on the Matching between the Straight Wing Non-articulated Vertical Axis Wind Turbine and the New Wind Turbine Generator

D105 明道大学における直線翼垂直軸型風力発電システムの実験的研究(風車性能1,OS-2 自然エネルギー(1),一般講演,地球温暖化防止と動力エネルギー技術)

D105 明道大学における直線翼垂直軸型風力発電システムの実験的研究(風車性能1,OS-2 自然エネルギー(1),一般講演,地球温暖化防止と動力エネルギー技術)

An Experimental Study on the Darrieus-Savonius Turbine for the Tidal Current Power Generation

The Darrieus turbine is popular for tidal current power generation in Japan. It is simple in structure with straight wings rotating around a vertical axis, so that it has no directionality against the motion of tidal flow which changes its direction twice a day. However, there is one defect in the Darrieus turbine; its small starting torque. Once it stops, a Darrieus turbine is hard to re-start until a fairly fast current is exerted on it. To improve the starting torque of the Darrieus turbine used for tidal power generation, a hybrid turbine, composed of a Darrieus turbine and a Savonius rotor is proposed. Hydrodynamic characteristics of a semi-circular section used for the Savonius bucket were measured in a wind tunnel. The torque of a two bucket Savonius rotor was measured in a circulating water channel, where four different configurations of the bucket were compared. A combined Darrieus and Savonius turbine was tested in the circulating water channel, where the effect of the attaching angle between Darrieus wing and Savonius rotor was studied. Finally, power generation experiments using a 48 pole electric generator were conducted in a towing tank and the power coefficients were compared with the results of experiments obtained in the circulating water channel.

Study on Wind Measurements and Annual Energy Production of a Darrieus Wind Turbine

Wind measurements and annual energy production of a Darrieus wind turbine with straight wing were measured from August, 2005 to July, 2006. The prediction value from measured wind speed of the annual electrical power output was compared with the measurement value. In winds where the turbulence intensity exceeded 20%, the rotational speed of the wind turbine decreased to 80% compared with the design value. Since the electrical power output is proportional to the 3rd power of rotational speed, the energy production decreased to 51% compared with the design value.

OS2-8 直線翼垂直軸風車の性能予測に関する研究(2)(OS2 自然エネルギー,循環型社会における動力エネルギー技術)

Researches about the aerodynamics of wind turbine with straight wing vertical axis (SW-VAWT) are very limited, in spite of a number of advantages such as low dependence on wind direction variation and easy constructible straight blades. For these reasons, we are researching the lift type SW-VAWT for many years. The elucidation of the behavior of the flow inside and neighborhood of the wind turbine during the rotation is very important because of the performance improvement of the vertical axis wind turbine. We estimated flow behavior during the wind turbine rotation by using this numerical simulation technique, and evaluated the flow around the wind turbine. This paper presents outline and results of these calculations and evaluations.