Maximum Lift Force Research Articles

A new airfoil design method for wind turbine to improve maximum lift of airfoil

A new wind turbine airfoil design method is established. This method generates an airfoil by fusing different airfoils. The airfoil designed by this method could restrict the airflow separation near the trailing edge of airfoil at high angle of attack, meanwhile the turbulence also is restricted. As a result, the maximum lift force is increased about 16.4% at high angle of attack. Meanwhile, the drag force is decreased about 31.3%. By analyzing the influence of scale factor and rotation angle on the airfoil aerodynamic force characteristics, the simulated results indicate that the larger scale factor and rotation angle could increase the lift stall angle and the maximum lift force. Therefore, this method could be used for designing wind turbine airfoil with high maximum lift force characteristics.

The effect of end conditions on the flow-induced vibration of circular cylinders in tandem arrangements

The current paper reports the results of in-water experiments to study the effect of end conditions on cross flow induced vibration (FIV) of a pair of circular cylinders in a tandem arrangement. The upstream cylinder remains fixed but the downstream cylinder is elastically mounted. The single degree of freedom vibrating system has a low mass-damping parameter (m*ζ= 0.012, to 0.013). The Reynolds number ranges from 3.5 × 103 to 4 × 104. Various spacing ratios (S/D= 2, 3, 4, 5 and 6) are examined. The upper end of the oscillating cylinder is the free water surface, but the lower one remains either with or without an endplate.Based on the experimental results it is concluded that the response category, say wake induced vibration (WIV), vortex induced vibration (VIV) or transition, does not change by the presence or absence of the endplate. With the WIV category, the oscillation amplitude (A*) is predominantly higher in the absence of an endplate and the maximum amplitude (A*max) may increase as much as 100%. The maximum lift force coefficient may increase as much as 25%. In the absence of the endplate, the lift force signals contain a perceptible 3rd sub-harmonic at both low and high reduced velocities. With the VIV type of response, the maximum amplitude is less significantly affected by the end conditions.

The effects of marine fouling on the wake-induced vibration of tandem circular cylinders

This paper reports the results of laboratory in-water experiments in which artificially marine-fouled circular cylinders were freely vibrating in the wake of a similar fixed upstream cylinder. Cross-flow vibrations at gaps of 3–7 diameters were examined. The marine fouling was simulated by CNC machining of uniformly distributed single-sized pyramids on the surface of the test cylinders. Depending on the spacing ratio, the smooth tandem cylinder demonstrated both Vortex-Induced Vibration (VIV) and galloping types of response. Interestingly, only the VIV-like response was presented by the artificially marine-fouled cylinder. The maximum amplitude of the oscillations and maximum lift force coefficient of the marine-fouled tandem cylinders were, respectively, around one-third and two-thirds of those in the corresponding smooth tandem cylinders. In the case of tandem circular cylinders, the marine fouling showed two contradictory outcomes. It eliminated the galloping and suppressed the VIV-like response, which is beneficial from structural integrity standpoint. From energy performance point of view, the marine fouling negatively affects the energy harvested in a marine hydrokinetic energy converter.

Circular Shell Gripper for Handling Food Products.

Pneumatically driven soft robotic grippers have been extensively studied in recent years. A majority of the grippers, especially those entirely composed of soft materials, can adapt to and handle various objects. However, there are limited studies regarding the realization of arbitrary grasping postures and twisting manipulation. Furthermore, the handling efficiency or the takt time of a handling task has not been investigated frequently. Therefore, this article proposes a circular shell gripper that consists of a rigid external shell and four soft internal air chambers. The soft chambers can be pneumatically inflated, thereby enabling it to grasp an object with a large contact area. The rigid shell allows the gripper to generate a large grasping force, while providing rigidity. This allows it to achieve arbitrary handling postures and twisting manipulations. A finite element model was constructed to simulate the chamber inflation, contact area upon grasping, lifting force, and twisting torque. An analytical model was formulated to quickly predict the lifting force and the twisting torque required to manipulate a known object. The models were validated via experimental tests on the lifting and twisting of a rigid cylinder. The experimental results indicate that the shell gripper can generate a maximum lifting force and twisting torque of 50.97 N and 0.73 Nm, respectively, with an input pressure of 10 kPa. Experimental tests on a variety of food and drink products revealed that the gripper could handle deformable, heavy, and irregularly shaped objects as well as realize arbitrary manipulation posture and twisting motion. The takt time for a pick-and-place task was found to be ∼2-5 s, using an SCARA robot; this time can be further optimized (less than 1 s) by using a parallel robot. However, the gripper was unable to handle low-profile objects, due to the downward pressing force; this was identified as a limitation of the proposed design.

Modeling and analysis of structure parameters on the lifting force for power catwalk

PurposeAs the excessive lifting force can lead to catwalk rollover and well site accidents, the lifting process boundary conditions and structural parameters have a significant effect lifting force, it is important to analysis the structural parameters on the maximum lifting force in the lifting process of power catwalk.Design/methodology/approachA new model is proposed to analyze the influence of structure parameters on its lifting force for lifting power catwalk in this paper, and the geometric and dynamic equations are established according to the different boundary conditions in different stages. In addition, the establishment of dynamics equations is based on D'Alembert's principle. To solve the model, dynamic analysis software is developed, which uses c # call MATLAB to solve the geometric and dynamic equations. The maximum lifting force is analyzed and optimized according to the software, the influence of structural parameters on the maximum lifting force is obtained and the correctness of the optimization is proved by experiments.FindingsThe best value of offset e is 0. The length of L22 should as small as possible while the installation size of the end of the conveying arm are guaranteed. The length of L1 should as small as possible while ensuring the not exceed the maximum value. The maximum lifting force remain the same in the second phase, the maximum lifting force decreases with the increase of Lcp, Lcpshould as small as possible. The maximum pressure of the hydraulic oil dropped by an average of 13.62% under optimized parameters.Practical implicationsThis paper provides a theoretical basis for the selection of hydraulic winch, which also provides the theoretical basis and data support for the design and optimization of the structural parameters of the power catwalk.Social implicationsThis research has industrial applications in SJ Petroleum Machinery CO.LTD, SINOPEC (China) .CANRIG, North Rig, TESCO, Sichuan HONGHUA petroleum equipment CO.LTD of CNPC., Baoji Oil field Machinery CO.LTD, SJ Petroleum Machinery Co. LTD of SINOPEC, Yantai Jereh Oilfield Services Group CO.LTD, Nanyang clips oil equipment (group) CO. LTD, etc are the likely users.Originality/valueA new model is proposed to analyze the lifting force of lifting power catwalk. The model takes into account the inertia force of the structure, development of dynamics software and analysis and optimization of structural parameters. The maximum lifting force is analyzed and optimized according to the software, the influence of structural parameters on the maximum lifting force is obtained and the correctness of the optimization is proved by experiments.

园艺电液控制系统液压装置的设计与试验

This paper proposed a structural design scheme of the hydraulic device of the electro-hydraulic controlled hitch system of a YM554A horticultural tractor with hydraulic device model, and the designed hydraulic device was simulated and tested to verify its performance. Results show that the motion of hydraulic actuator is stable with good response for tillage depth control, while the maximum lifting force of 10.62kN and the static settlement value of 13mm all meet the standard requirements. And the oil pressure changes rapidly with a large fluctuation with the plough position changed from transportation state to tillage state, but it quickly stabilizes, and as the tillage depth becomes larger, the oil pressure drops but remains basically stable with the maximum oil pressure change of 0.35MPa.

A Stiffness Adjustable 6-DOF Robotic System for Pituitary Tumor Resection Under MRI

Magnetic resonance imaging offers better visualization for tumors present in the delicate parts of the human body. A pituitary tumor is one of the common types of brain-related tumors located underside the brain. It can be accessed through the nostrils and visualized better using magnetic resonance imaging (MRI). In this work, we present a 6-degree-of-freedom (DOF) robotic system for pituitary tumor resection via a transsphenoidal approach designed specifically for a commercially available 3T MRI scanner. The robotic system is designed to follow the anatomical and surgical constraints and to work inside the bore of the MRI to allow image acquisition during the surgical procedure. It has a 6-DOF manipulator consisting of a concentric tube and a tendon-driven bendable section. Both mechanisms are merged to have stiffness changing capability, and payload capacity to aid the surgical task. The manipulator is attached to a flexure shaft to bend it at the desired surgical angles. The materials used for development are analyzed in MRI and exhibit signal-noise ratio (SNR) reduction of less than 10%. The experimental results show that the stiffness can be changed more than ten times for safe navigation to the surgical site without damaging the surrounding tissues. Also, it can provide a maximum lifting force of more than 2N. The presented system is the preliminary version of the pituitary tumor resection system under development and shows the feasibility to be used in a real surgical environment.

Numerical prediction of aerodynamic performance for a flying fish during gliding flight

Flying fish is a family of unique aerial–aquatic animals, which can both swim in the water and glide over the sea surface. Most previous studies on their aerodynamic characteristics were based on field observations or measurements of their morphometric parameters. In the present study, we consider three different flying fish models, of which the preliminary one mimics the Cypselurus hiraii in the pectoral fin morphology, following a previous wind tunnel experiment (Park and Choi 2010 J. Exp. Biol. 213 3269–79). Their aerodynamic performances are numerically studied by the computational fluid dynamics (CFD) method. The maximum lift force coefficient of 1.03 is reached at the angle of attack , and the maximum lift-to-drag ratio of 4.7 is achieved at . By choosing appropriately the center of gravity, the flying fish model is proved to be longitudinally stable, according to the negative slope of pitching moment profile. Furthermore, we build a three-degrees-of-freedom (3-DOF) dynamic model in the longitudinal plane based on the aerodynamic coefficients obtained in our simulations, to predict its gliding performance. The results show that the flying fish can achieve a distance up to 45.4 m, and reach a height of 13.2 m, indicating an extraordinary gliding performance. Our numerical simulations are consistent with previous experimental results and theoretical prediction, which can be taken as the basis of further research on robotic flying fish.

Design, modelling and control of collaborative samara autorotating wings (SAW)

Current methods of airdropping payloads accurately use the autonomously guided parafoil systems. Such approaches have limited trajectory options, hence limited accuracy, and could deliver only one payload with one airdrop. The Samara Autorotating Wings (SAW) is disposable type of aerial deployment system proposed in this paper to drop light-weight electronic payloads to remote locations accurately. Using autorotation as its main technique of lift creation, the concept borrows the natural dispersion method from maple seeds and takes advantage of the gyroscopic stability of a spinning mass. It does not require any propulsion system on-board and is equipped with an actuator to change the angle of attack of the wing for directional control. The concept also features a collaborative autorotation mode whereby multiple wings are attached together to form a larger rotor hub that benefits from increased angular momentum and control authority which is especially important at higher altitudes where the air is less dense. Although there have been other works on using autorotation to deliver payloads, this is the first documented effort in using a collaborative form of autorotation. The chordwise geometrical wing shape of SAW is optimized to achieve the maximum lift force during its autorotating descent. A nonlinear control method is conceived to regulate the descent direction and speed of SAW. This proposed control scheme enables an omni-directional guide slope, allowing SAW to be more maneuverable than parafoils or fixed-wing type of aerial deployments. SAW with different numbers of wings are tested against each other for drop characteristics and control performance, in simulated models and in physical experiments that involve a vertical wind tunnel with and integrated motion-captured system and free-fall drop tests.

Aerodynamic Characteristics of Elastic Wings Morphed and Vibrated in Uniform Flows and Separated Flows Around Them

In this study, experimental investigation is performed into modification to aerodynamic characteristics by distortion and vibration of planar wings with various Young’s modulus as well as flow fields around them. Motions of the wings are captured with a high-speed camera. Flows around them are evaluated with phase locked PIV technique. As a result, bending vibration of the wings is observed almost all over the angles of attack while twisting is observed around the angles giving maximum lift force. The twisting vibration causes larger aerodynamic forces and delay in the stall. It is found that amplitude of the twisting determines magnitude of variations in aerodynamic forces. Flow field measurement shows the twisting vibration generates periodic vortices shedding from the leading and trailing edges. They reduce the separation bubble on the wing, in particular, around the middle span in spite of localization of the twisting in the vicinity of the wing tip.

Evaluation of the Influence of Icing on Wings on Aircraft Flight Parameters

Abstract The phenomenon of icing is the process of changing the state of concentration of water contained in the atmosphere in the form of water vapor into a solid form deposited on the elements of the construction of aircraft. This phenomenon has a negative effect on the flight mechanics of the aircraft. The settling ice structures change the shape of the airfoil, which causes a reduction in the maximum lift force coefficient of the airfoil and, consequently, a reduction in the value of the lift force generated by the airfoil. As a result of icing, the weight of the aircraft increases, while its drag of movement increases. Deterioration of flight properties of the aircraft translates into increased fuel consumption. To assess the effect of icing of the wings on the flight parameters of the aircraft, numerical simulations of the prepared wing models were performed: clean, airfoil shaped icing structure, solid icing structure. The analysis of the change of the lift force, airfoil drag and the increase of the wing’s weight was carried out. The results, analysis and conclusions from the conducted research are presented in this article.

Towards an understanding of marine fouling effects on VIV of circular cylinders: Aggregation effects

The current study is aimed at getting a further insight into the changes the fouling brings to the Vortex Induced Vibration (VIV) of circular cylinders. Instead of regular patterns considered in previous studies, using the Poisson Cluster Process, an aggregated spatial distribution was considered for the artificial marine fouling. This is believed to better simulate the natural settlement of the marine biofouling. Different coverage ratios and fouling shapes plus regular and aggregated distributions were considered. The towing tank VIV tests were conducted on elastically mounted rigid cylinders. The Reynolds number ranged from around 7.8 × 103 to 4.9 × 104.On the whole, the maximum oscillation amplitude and the maximum lift force coefficient were meaningfully smaller in cylinders with either aggregated or regular fouling, as compared to those from the corresponding clean cylinder. Both aggregated and regular fouling were, thus, acting as VIV suppression devices. The suppression effectiveness increased by reduction in the coverage ratio of the artificial fouling. The effectiveness, however, reduced by the aggregation as compared to that with regular distribution. In general, the maximum VIV oscillations and the force coefficients appeared to be sensitive, in descending order, to coverage ratio, aggregation, flow incidence and the fouling shape.

Design Optimization, Modeling, and Control of Unmanned Aerial Vehicle Lifted By Coandă Effect

The Coanda effect is a natural phenomenon, which is that flowing fluid on a certain surface is pulled to the surface due to the viscosity of the fluid. This phenomenon can be utilized to produce the lift force of a flying object. This paper presents a new type of unmanned aerial vehicle (UAV) lifted by the Coanda effect, called SCoanda. We introduce the empirical study of its design and implementations. The principle of the Coanda effect is briefly explained in the first section. The design optimization and control of the UAV, and implementation issues are explained. The structural design of SCoanda is devised to use the maximum lift force produced by the Coanda effect. Since there are a plenty of cases about the shape of SCoanda, it has been limited to oval. It is investigated through computational fluid dynamics. As the result, an optimized design is determined among several candidates and appropriate structural materials are selected via tests. Also, dynamic modeling is suggested under several conditions of SCoanda before simulations are conducted to build up a controller and determine gains according to the dynamic modeling. Finally, the UAV is manufactured and its performances are successfully demonstrated in the indoor and the outdoor environments.

저층 트롤에서 3차원 위치를 이용한 만곡형 전개판의 영각 추정

The angle of attack of a cambered otter board in a bottom trawl was estimated using a three-dimensional semi-analytic treatment of a towing cable (warp) system that was applied to the field experiments of a bottom trawl obtained by the Scanmar system. The equilibrium condition of the horizontal component and vertical component of forces was used to the three forces acting on the otter board in the horizontal plane. Those forces were the force on the warp at the bracket, hydrodynamic lift and drag forces on the otter board and the force on the hand rope attached just behind the otter board. Also the equilibrium of moment about the front edge of the otter board was used to find out the angle of attack of the cambered otter board. When the warp length was 120m and 180m long and the towing speed was between 1.23 and 1.90 m/s, the estimated angle of attack of the cambered otter board was ranged between and , respectively, though the maximum lift force was at the angle of attack . The angle of attack of the otter board was tended to increase weakly with the longer length of warp (180 m) at the same towing speed in the experiment.

Lifting Force Calculation and Safty Analysis of Hydraulic Scissor Lift Platform

Based on the structure, the hydraulic scissor lift platform can be divided into different component modules. The maximum lifting force is calculated in accordance with its structure features, and then the safty is analyzed.

Optimal Three-Point Hitch Design to Maximize Lifting Performance

<abstract> <bold><sc>Abstract.</sc></bold> The three-point hitch mounted on tractors was introduced by Ferguson in 1935 and has been modified from the first patent with the introduction of different controls. In recent years, the geometry has not been significantly modified due to the standards that define the application limits. These standards define the geometric constraints of the system as a function of the tractor power and wheelbase. The constraints have been fixed to standardize the connection with implements and limit their movements. The degrees of freedom could be used to optimize the three-point hitch as a function of the design specifications, and in particular to optimize the maximum lifting capacity. Analysis of OECD-approved reports, confirmed by the authors’ experience, shows a high number of three-point hitches with a maximum lifting capacity that is not optimized. The goal of the present work is to provide a design tool to optimize the three-point hitch by maximizing the lifting capacity and satisfying the constraints fixed by the standards. The methodology proposed uses a constrained optimization technique and was validated on an existing three-point hitch. The optimized three-point hitch permits a maximum lifting force about 25% greater than the existing value. The lift arm length, the lower link length, and their pivot point positions are the variables with greatest influence on the objective function. The constraint of a minimum angle of 10° between the mast and the vertical axis is the most limiting constraint on the objective function.

Years devoted to development of aerodynamics in Siberia

April 29, 2014 is the 100th anniversary of Vladimir V. Struminskii. He was born in Orenburg in a family of a school teacher Vasilii Ya. Struminskii (1880–1967) and his wife Mariya F. Dmitrovskaya (1884−1972). After studying at school for seven years, he worked as a turner at a factory in Kazan and then at the Dinamo plant in Moscow. In 1933, without leaving his work, Vladimir Struminskii graduated from the school for working youth and entered the Physical Faculty of the Lomonosov Moscow State University. After graduating from the university cum laude, V.V. Struminskii became a post-graduate student at the Institute of Physics at the Moscow State University; in 1941, he defended the candidate’s thesis entitled “Electron theory of solids,” where he presented a solution of the Schroedinger equation for the crystal lattice of alloys. On the eve of the Great Patriotic War, Vladimir V. Struminskii was appointed to the Central Aerohydrodynamic Institute named after Academician N.E. Zhukovskii (TsAGI), where he started to study some problems new for him: aerodynamic investigations of finitespan wings. Several years later, he developed a method for calculating the maximum lift force of the wing and the distribution of stall zones over the wing span. A series of experiments with finite-span wings in the full-scale wind tunnel based at TsAGI at high Reynolds numbers confirmed the efficiency of the proposed method of aerodynamic design of the wing. In 1947, Struminskii together with other TsAGI researchers was awarded with the State Prize for the development of new wings for high-velocity airplanes and preparation for their batch production. V. V. Struminskii made a significant contribution to the progress in aeronautics by developing a method of aerodynamic design of the wing from a set of airfoils with a nonseparated flow at the wing tip, which ensured high reliability and safety of flight at high angles of attack; this method was developed during the Great Patriotic War. Before that, a large amount of theoretical activities were performed. Exact solutions of three-dimensional boundary layer equations

Mechanical Analysis and Strength Evaluation of KEY COMPONENTS Tripod of SNUBBING UNIT

Tripod is the key components of snubbing unit, its strength directly affect the normal work of snubbing unit. Considering the structure and force characteristics of key components tripod of snubbing unit, three-dimensional finite element analysis model of tripod is established. By using the finite element method, mechanical analysis of tripod is conducted and safety evaluation is finished by adopting the stress classification and introducing analysis design standard of pressure vessel. The results show that key components tripod of snubbing unit are safe and reliable under the maximum lifting force and the maximum downward force. It provides theory evidence for snubbing unit design. The safety evaluation method provides effective evaluation methods for complex structure strength evaluation.

Optimization Design Study of Loader Working Mechanism Based on MATLAB Complex Method

The paper makes an analysis on the working device of loader, which plays an important role in the performance and economic benefit of the overall unit. The paper tries to develop the mathematical model of a loader working device, apply complex method taking the maximum breakout force of cylinder of rotating bucket as well as maximum lifting force of boom cylinder as the objective function and finally realize the optimization design of its design based on MATLAB software, probing into finding a efficient solution for the technical problems existing in the working device design and manufacturing.

Optimization of Lift Force of Mini Quadrotor Helicopter by Changing of Gap Size between Rotors

This paper describes comparison between virtual simulation of quadrotor flying platforms (mini UAV - Unmanned Aerial Vehicle) and real experiments. In quadrotor helicopter (quadrocopter) air flows that are going out from rotors and affecting each other were simulated. Analysis of several helicopters that have different distances between rotors on different angular velocities were compared. During virtual simulation (with CFD Computational Fluid Dynamics software) there were conducted similar to real experiments with the use of scanned rotors (with 3D scanner) and same environment conditions. These experiments were compared with real experiments. Optimal gap distance between rotors is determined, when helicopter mass is minimum and rotors are creating maximum lifting force and consuming minimum energy (minimum impact on air flows to each other).