Papers by Keyword: Lift

Abstract: At present, pruning of fruit trees on hills is mainly completed by climbing on trees or ladder, which could cause injury due to poor landform. In order to avoid such kind of risks, it is important to develop a lifting platform for orchards in hilly area. In this paper its structure and working mechanism were introduced. This lifting platform, as a machine, is comprised of power device, elevating mechanism, leveling mechanism, slewing mechanism, supporting mechanism and hydraulic control system, and is driven by a small four-wheel tractor. Its hydraulic system can control hydraulic cylinders to extend and retract so as to lift, lower, rotate or keep platform at horizontal position. By analyzing the machine’s kinematic model, the mode of hydrostatic triangle leveling was determined. In order to simplify the machine’s structure, a cantilever beam was used as a supporting mechanism. After carried out the performance test for the machine, the results show that the machine has the following features: stable working performance, the maximum load up to 150 kg, the lifting height 1.5 m, the rotating speed 1 r/min, the lifting velocity 0.1 m/s, and leveling error in lifting process no more than 2° (no matter on horizontal plane or on slopes). So the machine can be suitable for sloped terrain, and the design requirements are well satisfied.

Abstract: This paper is primarily concentrated with determining aerodynamic characteristics and choosing the best angle of attack at a maximum lift and low drag for the FX 63-137 aerofoil at a low Reynolds number and a speed of 20m/s and 30m/s, by using subsonic wind tunnel through manufacturing the aerofoil by aluminum alloy using a CNC machine. The proposed methodology is divided into several stages. Firstly, manufacturing the aerofoil using an aluminum alloy. Secondly, the testing process is carried out using subsonic wind tunnel. Thirdly, the results are displayed and compared with results produced from related works, in order to find out the best angle of attack at a maximum lift.

Abstract: Use of low fidelity tools in designing subscale generic wind tunnel models is usually required to get first-hand knowledge about general trends of aerodynamic and stability parameters. Most of such tools are limited to well-defined conventional aircraft configurations. In the present work, aerodynamic and stability characteristics of a winged hybrid airship is explored at low subsonic speed by using Aircraft Digital DATCOM, which is based on semi-empirical methods for preliminary aircraft geometries. Spheroidal ellipsoidal shaped hull of the airship is modeled in DATCOM along with the geometrical details of wing and empennages. The prediction of zero lift drag coefficient, coefficient of lift and pitching moment is the focus of this paper. Except the drag coefficients, trends of analytical results compare well with experimental data.

Abstract: In the present study, the aerodynamic characteristics such as time-averaged lift and drag generation of two flexible membrane (latex thin and thick) wings with different skin flexibilities are compared with those of a conventional rigid (wood) wing to assess the effects of skin flexibility (rigidity) on the aerodynamic performance for flapping flight applications. The experiments are performed in an open circuit wind tunnel of non-return airflow with a test section of (0.3m x 0.3m) and is capable of speeds from 0.5 to 30 m/s. The time-averaged lift and drag as functions of flapping frequency, forward flight velocity and the orientation angle of the flapping motions with respect to the incoming flows are measured by using a strain gauge balance and KYOWA PCD-300A sensor interface data acquisition system. It has been found that flapping motion would bring significant aerodynamic benefits when the flapping flight is in unsteady state regime, with advance ratio less than 1.0. The aerodynamic benefits are found to decay exponentially with the increasing advance ratio. Flapping motion is found to become detrimental for high speed flight applications. It is also observed that the skin flexibility has considerable effect on the aerodynamic performance. The flexible latex thick wing is found to have better overall aerodynamic performance over the rigid wing, especially for low speed applications. The wood (rigid) wing exhibited better lift production performance in quasi steady regime.

Abstract: It is vital to reduce lift generated by a racing car while traveling with high speed for the sake of overall performance and stability. Simplified formula student racing car models with seven diffuser angles and without diffuser were simulated based on CFD technology. Aerodynamic forces and corresponding coefficients were achieved for all eight models. The calculated results show that the lift generated by the car in the high speed can be reduced by a diffuser effectively. The aerodynamic characteristics of a racing car will be greatly improved by adding a rational designed diffuser, which may cut down lift dramatically with only little drag produced. This paper provides theoretically support for improving racing car aerodynamic characteristics.

Abstract: Rear wing is the most predominant element to racing car aerodynamics. Double tail race car would be the most suitable choice to make a brilliant balance between cost and performance. A simplified formula student racing car model was simulated employing CFD method. The double tail was carried on four factors four levels orthogonal design method and the optimal value of each factor was achieved. The results show that the whole car aerodynamic performance can be improved with the appropriate position and angle of attack of the double tail.

Abstract: Integrated construction technology is widely applied for offshore modules these years, which contains multiple disciplines works such as structure, mechanism, piping, coating, electricity and instrument, etc.. Herein, this technology puts forward new requirements in pallet transportation and lifting process due to uncertainty factors. Therefore, it is highly significant to come up for a detailed discussion at application of offshore module integrated construction technology. This paper particularly depicts some key technologies in transportation and lifting process, including synchronous jacking system, trailer, confirmation of pallet weight and center of gravity, padeyes, clash check of lifting and so on. This paper proposes referring transportation and lifting methods in integrated construction, and it will greatly benefit for offshore module construction.

Abstract: In the paper a lift calculation of a two-dimensional airfoil with a plain flap and Krueger flap is investigated. Numerical-analytical method (NAM) is used to predict the flow field around this combination. In order to calculate the complex velocity in the flow field, the complex variable function theory is employed. NAM based on the joint application of conformal mapping and the discrete vortex method (DVM). The paper presents a brief description of the NAM and some results of the lift calculations of the airfoil with the plain flap and Kruger flap. Comparison of the calculation results with the theoretical data of other authors showed a good agreement.

Abstract: The present investigation deals with different Ergonomical features, especially the humans – machines interaction and the problems associated with it. Attempts were made to acquire anthropometric data of the workers engaged in one of the gear manufacturing and assembling industry located at Coimbatore. Various angular movements exerted with respect to the wrist, forearm and upper arm of the worker on different equipments while pushing and pulling and lifting and carrying tasks were recorded to analyze the various working postures and problems associated with it.The analysis was carried out for two different trolleys which were used in their work place. The problems were identified and suggestion was given to industry. A redesigned trolley based on Ergonomic principles helped to alleviate the problems of the workers.

Abstract: Any aircraft wing is the major component which will play vital role in the generation of lift and at different maneuvering moments throughout the flight. So to maintain this good maneuverability the aircraft wing has to undergo deferent deflections called angle of attack such that the high lift and low drag or vice versa can be settled in the flight. Taking this as the motivation the analysis was carried out on the standard wing airfoil comparing with new designed airfoil. Analyze the numerical simulation values like coefficient of lift, coefficient of Drag, Lift, Drag, and Energy parameters with wind tunnel data to predict accuracy for both the airfoils. Through the selected public literature standard airfoil data and designed airfoil data has been chosen, the geometry was created in the GAMBIT and also the meshing by selecting the suitable c-grid and rectangular grid for the better flow analysis in the FLUENT. The mesh file was imported into the FLUENT software there suitable boundary conditions and operating conditions are given for successful flow convergence. Finally analyzing these results are expecting to be best suitable for good aeromechanical features.