scholarly journals Serve Ball Trajectory Characteristics of Different Volleyballs and Their Causes

2021 ◽  
Vol 11 (19) ◽  
pp. 9269
Author(s):  
Takehiro Tamaru ◽  
Masaki Hiratsuka ◽  
Shinichiro Ito
Keyword(s):  
Wind Tunnel ◽  
Drag Force ◽  
Force Measurement ◽  
Lateral Force ◽  
Aerodynamic Characteristics ◽  
Flight Distance ◽  
Wind Tunnels ◽  
Fluid Force ◽  
Precise Control ◽  
Ball Trajectory

A floater serve in volleyball is a technique of serving a non-rotating or low-rotating ball, which is difficult to return because the flight path of the ball changes irregularly. On the other hand, the randomness of the trajectory makes it difficult for the ball to fall on the target. Players are required to serve taking into account the variability of the trajectory. In previous studies using wind tunnels, it was shown that aerodynamic characteristics such as drag force and lateral force applied to the ball vary depending on the type of ball and the orientation of the panel. Therefore, in order to control the flight trajectory, it is necessary to understand the aerodynamic characteristics of each ball. Since the velocity of the ball and the fluid force applied to the ball changes during flight, it is important to measure not only the fluid force at a steady state in the wind tunnel but also the actual flight distance of the ball. In this study, to provide valuable information for precise control of floater serves, we measured the drag force applied to the ball in a wind tunnel and the flight distance of the ball using an ejection machine, and clarified the effects of the type of ball and the panel face. In the drag force measurement, the drag force on three types of balls, V200W, MVA200, and FLISTATEC, was measured in the wind speed range of 4 m/s to 30 m/s. In the ejection measurement, the ball flight distances were measured while changing the orientation of the panel using an ejection machine. Basically, the FLISTATEC, MVA200, and V200W, in that order, were more likely to increase the distance and the variability, but it was shown that the drop point could be adjusted slightly by selecting the panel face. This result was also obtained when a human player actually served the ball, indicating the tactical importance of the player consciously controlling the direction of the panel. The tactical importance of the player’s conscious control of the direction of the panel was demonstrated. We also proposed receiver positions that would be effective based on the characteristics of each ball.

scholarly journals Serve Ball Trajectory Characteristics of Different Volleyballs and Their Causes

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 146
Author(s):  
Takehiro Tamaru ◽  
Shinichiro Ito ◽  
Masaki Hiratsuka
Keyword(s):  
High Speed ◽  
Trajectory Analysis ◽  
Force Measurement ◽  
Aerodynamic Characteristics ◽  
Flight Trajectory ◽  
Fluid Force ◽  
Spin Speed ◽  
Trajectory Measurement ◽  
Ball Trajectory ◽  
Effective Service

Volleyball is a sport that starts with a serve, so effective service is essential to win the game. The trajectory of the ball is complicatedly affected by the fluid force, which depends on the speed, spin speed, and panel shape. To understand the aerodynamic characteristics of the ball and to propose an ideal serve method, we measured the fluid force and flight trajectory. The fluid force applied to the ball was measured at a wind speed of 4–30 m/s in the wind tunnel. The fluid force on the ball was strongly dependent on the ball type and orientation of the panel. In the flight trajectory measurement, the trajectory of the ball was measured using a high-speed camera under controlled speed and spin speed using a shotting machine. The effect of the panel orientation shown by the fluid force measurement was consistent with the results of the trajectory analysis, clarifying the importance of the panel orientation in serving.

scholarly journals Methodology for calculating the efficiency of the rudders of the tandem aircraft

2021 ◽  
pp. 11-21
Author(s):  
Illya Bilous ◽  
Illya Kryvohatko ◽  
Yurii Yakovlev
Keyword(s):  
Wind Tunnel ◽  
Rapid Development ◽  
Aerodynamic Characteristics ◽  
Wind Tunnel Experiment ◽  
Wind Tunnels ◽  
Analysis Tool ◽  
It Impacts ◽  
Characteristics Analysis ◽  
The Stability

As of recent rapid development in the field of UAVs, unusual aerodynamic practices can be used, for example, the tandem scheme. In early planning stages, it’s important to evaluate aerodynamic characteristics of the chosen scheme and to approximate its balancing losses, as it impacts the stability and controllability of the craft. The most effective way of aerodynamic characteristics analysis is done using wind tunnels. However, it requires considerable investments in both financial terms and time, when designing the model, conducting the experiment and processing the results. Because of that, it’s worthwhile to consider the simple CFD calculations (XFOIL). This paper calculates aerodynamic characteristics of a tandem-scheme based “A-8” aircraft using XFLR5 analysis tool with the results compared to a real wind tunnel experiment. The overall conclusion of the paper is a recommendation to consider XFLR5 for early planning stages for advanced balancing losses calculation approximation.

Investigation of rapid manufacturing technology with ABS material for wind tunnel models fabrication

2012 ◽  
Vol 32 (8-9) ◽  
pp. 575-584 ◽  
Author(s):  
Saeed Daneshmand ◽  
Cyrus Aghanajafi ◽  
Hossein Shahverdi
Keyword(s):  
Surface Roughness ◽  
Wind Tunnel ◽  
Raw Materials ◽  
Dimensional Accuracy ◽  
Aerodynamic Characteristics ◽  
Wind Tunnels ◽  
Rapid Manufacturing ◽  
Material Strength ◽  
Wind Tunnel Testing ◽  
Tunnel Testing

Abstract Nowadays, several procedures are used for manufacturing wind tunnel models. These methods include machining, casting, molding and rapid prototyping. Raw materials such as metals, ceramics, composites and plastics are used in making these models. Dimension accuracy, surface roughness and material strength are significant parameters which are effective in wind tunnel manufacturing and testing. Wind tunnel testing may need several models. Traditional methods for constructing these models are both costly and time consuming. In this research, a study has been undertaken to determine the suitability of models constructed using rapid manufacturing (RM) methods for use in wind tunnel testing. The aim of this research is to improve the surface roughness, dimensional accuracy and material strength of rapid manufacturing models for testing in wind tunnels. Consequently, the aerodynamic characteristics of three models were investigated and compared. The first model is made of steel, the second model from FDM-M30, and the third model is a hybrid model. Results show that metal models can be replaced by hybrid models in order to measure aerodynamic characteristics, reduce model fabrication time, save fabrication cost and also to verify the accuracy of aerodynamic data obtained in aerospace industry.

A Modular Wing-Tail Airplane Configuration for the Educational Wind Tunnel Laboratory

2004 ◽  
Author(s):  
B. Terry Beck
Keyword(s):  
Wind Tunnel ◽  
Rapid Prototyping ◽  
Calibration Procedure ◽  
Aerodynamic Characteristics ◽  
Wind Tunnels ◽  
Small Scale ◽  
Pitching Moment ◽  
Gravity Effects ◽  
Basic Parameters ◽  
Rapid Prototyping System

An innovative modular airplane configuration has been developed for use in small-scale educational wind tunnels. The “airplane” consists of an interchangeable wing and horizontal tail configuration that mounts on a conventional wind tunnel electronic balance (“sting”) to facilitate measurements of normal force, axial force and longitudinal pitching moment. From these basic parameters, the total lift, total drag, and resultant airplane pitching moment can be deduced, along with the location of the aerodynamic center of the total airplane. Using known wing planform and airfoil shapes facilitates comparison of the total airplane aerodynamic characteristics with those predicted from the known characteristics of the separate wing and horizontal tail. In particular, the aerodynamic center of the simplified airplane configuration can be determined, along with the effect that downwash on the tail has on longitudinal stability of the airplane. Included in the paper is a description of the calibration procedure for the modular “sting” mount. This procedure accounts for an offset “line of action” for aerodynamic forces, as well as offset center of gravity effects. In conjunction with this same test setup, an available Rapid Prototyping system has been used to manufacture the test sections (separate wing and tail) for use in the wind tunnel, and in particular, in the modular wing-tail assembly. This provides tremendous flexibility in the types of wing-tail assemblies that can be investigated experimentally using the same module. The relatively inexpensive prototyping procedure also provides the capability for students to design and test their own configurations. Furthermore, the precision manufacturing capability of the Rapid Prototyping system guarantees reliable reproduction of virtually any desired aerodynamic planform and airfoil shape.

A Simple Device for Wind Tunnel Performance Testing of Small Scale Powered Propellers

2005 ◽  
Author(s):  
B. Terry Beck ◽  
Nelson A. Pratt
Keyword(s):  
Wind Tunnel ◽  
Rotation Speed ◽  
Force Measurement ◽  
Performance Testing ◽  
Test Facility ◽  
Wind Tunnels ◽  
Small Scale ◽  
Torque Measurement ◽  
Measurement Device ◽  
Propeller Design

Propellers represent an interesting application of the principles of aerodynamics. The basic physics of propeller operation can be modeled as a rotating wing section using classical blade element analysis procedure, which can also include flows induced by the propeller motion itself. Performance testing of small-scale powered propellers in modest size educational wind tunnels could yield important verification of these analysis tools, and also provide valuable experimental insight into important aspects of propeller design for the engineering laboratory. To provide useful data, measurements of propeller performance must include not only rotation speed and thrust, but also torque. These variables need to be investigated as a function of the imposed wind tunnel airspeed, which represents the forward speed of a powered propeller in flight. Rotation speed is easily measured using a variety of simple optical (including stroboscopic) techniques and thrust simply corresponds to the axial force measurement obtained directly from the typical “sting” balance used with educational wind tunnels. However, commercial devices for practical torque measurement can be quite expensive and are also typically of much higher torque range than that achieved by small-scale propellers designed for model airplane use, which limits their usefulness in the educational engineering wind tunnel laboratory. This paper presents a simple and inexpensive strain gage based device designed for measurement of low level torque developed by small-scale powered propellers. The operating principles of the torque measurement device are described, along with static calibration test results and experimental measurements of the performance characteristics of a small-scale electric motor driven powered propeller using our educational wind tunnel test facility. The torque sensor can be combined with rapid prototyping propeller design to allow investigation of a wide variety of propeller design features. Additional planned improvements and other wind tunnel applications for the torque measurement device are also discussed in the paper.

Aerodynamical Improvement of Delta Wing and Flapping Wing

2015 ◽  
Author(s):  
Tadateru Ishide ◽  
Kazuya Naganuma ◽  
Shinsuke Seiji ◽  
Hiroyuki Ishikawa ◽  
Ryo Fujii ◽  
...  
Keyword(s):  
Force Measurement ◽  
Delta Wing ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Flapping Wing ◽  
Fluid Force ◽  
Unmanned Air Vehicle ◽  
Wide Range ◽  
Air Vehicle ◽  
Piv Analysis

Recently, various studies of Micro Air Vehicle (MAV) and Unmanned Air Vehicle (UAV) have been reported from wide range points of view. The aim of this study are researching the aerodynamic improvement of delta wing and flapping wing in low Reynold’s number region to develop an applicative these air vehicle. Various configurations of Leading Edge Flap (LEF) are used to enhance the aerodynamic characteristics in the delta wing. The six kind of elliptical wings made of stainless steel are used in the flapping wing. The effects of flapping amplitude and wing configuration regarding the aerodynamic characteristics are investigated in detail. The fluid force measurement by six component load cell and PIV analysis are performed as the experimental method. In the flapping wing experiment, the simultaneous measuring of the fluid force measurement and PIV analysis is tried by using the trigger signal from the encoder attached to the flapping model. The relations between the aerodynamic superiority and the vortex behavior around the models are demonstrated.

Shape optimization and experimental research of near space airship

2018 ◽  
Vol 233 (10) ◽  
pp. 3589-3602
Author(s):  
Dongli Ma ◽  
Guanxiong Li ◽  
Muqing Yang ◽  
Shaoqi Wang ◽  
Liang Zhang
Keyword(s):  
Wind Tunnel ◽  
Shape Optimization ◽  
Drag Coefficient ◽  
Force Measurement ◽  
Wind Tunnel Test ◽  
Volume Ratio ◽  
Aerodynamic Characteristics ◽  
Near Space ◽  
Transition Position ◽  
Favorable Pressure Gradient

Shape optimization has important effects on drag reduction of the near-space airship. This paper uses the Bezier curve to parameterize the hull of the airship. Based on multiple island genetic algorithms, the optimization platform combined with different programs is established, and a kind of low drag hull is obtained by optimization. Force measurement and flow observation wind tunnel test are used to research the aerodynamic characteristics of the ellipsoid hull and the optimized hull. Results show that, optimization mainly increases the volume ratio and the favorable pressure gradient region of the hull, therefore the surface area is reduced and transition position of the hull can be delayed. Compared with the LOTTE shape, transition position of the optimized shape moved backward by 13.78%, and the volume drag coefficient is reduced by 11.1%. It is known from the wind tunnel test that compared with the ellipsoid hull, transition position of the optimized shape moves backward obviously. Under the condition that the volume Reynolds number is 2.97 × 106, compared with the ellipsoid hull, volume drag coefficient of the optimized shape can reduce by 39.0%.

Effect of the inter-car gap length on the aerodynamic characteristics of a high-speed train

2018 ◽  
Vol 233 (4) ◽  
pp. 448-465 ◽  
Author(s):  
Tian Li ◽  
Ming Li ◽  
Zheng Wang ◽  
Jiye Zhang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Drag Force ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Wind Tunnel Experiments ◽  
The Impact

In wind tunnel experiments, the inter-car gaps are designed in such a way as to separate the force measurements for each car and prevent the interference between cars during tests. Moreover, the inter-car gap has a significant effect on the aerodynamic drag of a train. In order to guide the design of the inter-car gaps between cars in wind tunnel experiments, the impact of the inter-car gap length on the aerodynamic characteristics of a 1/8th scale high-speed train is investigated using computational fluid dynamics. The shear stress transport k-ω model is used to simulate the flow around a high-speed train. The aerodynamic characteristics of the train with 10 different inter-car gap lengths are numerically simulated and compared. The 10 different inter-car gap lengths are 5, 8, 10, 15, 20, 30, 40, 50, 60, and 80 mm. Results indicate that the aerodynamic drag coefficients obtained using computational fluid dynamics fit the experimental data well. Rapid pressure variations appear in the upper and lower parts of the inter-car gaps. With the increase of the inter-car gap length, the drag force coefficient of the head car gradually increases. The total drag force coefficients of the trains with the inter-car gap length less than 10 mm are practically equal to those of the trains without inter-car gaps. Therefore, it can be concluded from the present study that 10 mm is recommended as the inter-car gap length for the 1/8th scale high-speed train models in wind tunnel experiments.

scholarly journals Aerodynamic characteristics of a free-flight scramjet vehicle in shock tunnel

2021 ◽  
Vol 62 (7) ◽  
Author(s):  
Marie Tanno ◽  
Hideyuki Tanno
Keyword(s):  
System Analysis ◽  
Force Measurement ◽  
Prediction Interval ◽  
Angular Acceleration ◽  
Aerodynamic Characteristics ◽  
Measurement Precision ◽  
Shock Tunnel ◽  
Free Flight ◽  
Vehicle Model ◽  
Aerodynamic Test

Abstract A multi-component aerodynamic test for an airframe-engine integrated scramjet vehicle model was conducted in the free-piston shock tunnel HIEST. A free-flight force measurement technique was applied to the scramjet vehicle model named MoDKI. A new method using multiple piezoelectric accelerometers was developed based on overdetermined system analysis. Its unique features are the following: (1) The accelerometer’s mounting location can be more flexible. (2) The measurement precision is predicted to be improved by increasing the number of accelerometers. (3) The angular acceleration can be obtained with single-axis translational accelerometers instead of gyroscopes. (4) Through the averaging process of the multiple accelerometers, model natural vibration is expected to be mitigated. With eight model-onboard single-axis accelerometers, the three-component aerodynamic coefficients (Drag, Lift, and Pitching moment) of MoDKI were successfully measured at the angle of attack from 0.7 to 3.4 degrees under a Mach 8 free-stream test flow condition. A linear regression fitting revealed a 95% prediction interval as the measurement precision of each aerodynamic coefficient. Graphical abstract

Aerodynamics of Cyclist Posture, Bicycle and Helmet Characteristics in Time Trial Stage

2012 ◽  
Vol 28 (3) ◽  
pp. 317-323 ◽  
Author(s):  
Vincent Chabroux ◽  
Caroline Barelle ◽  
Daniel Favier
Keyword(s):  
Statistical Analysis ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Drag Force ◽  
Time Trial ◽  
Frontal Area ◽  
Significant Gain ◽  
Upper Limbs ◽  
Force Coefficient ◽  
Coefficient Reduction

The present work is focused on the aerodynamic study of different parameters, including both the posture of a cyclist’s upper limbs and the saddle position, in time trial (TT) stages. The aerodynamic influence of a TT helmet large visor is also quantified as a function of the helmet inclination. Experiments conducted in a wind tunnel on nine professional cyclists provided drag force and frontal area measurements to determine the drag force coefficient. Data statistical analysis clearly shows that the hands positioning on shifters and the elbows joined together are significantly reducing the cyclist drag force. Concerning the saddle position, the drag force is shown to be significantly increased (about 3%) when the saddle is raised. The usual helmet inclination appears to be the inclination value minimizing the drag force. Moreover, the addition of a large visor on the helmet is shown to provide a drag coefficient reduction as a function of the helmet inclination. Present results indicate that variations in the TT cyclist posture, the saddle position and the helmet visor can produce a significant gain in time (up to 2.2%) during stages.

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