Identification of Release Conditions and Aerodynamic Forces in Pitched-Baseball Trajectories

2001 ◽  
Vol 17 (1) ◽  
pp. 63-76 ◽  
Author(s):  
LeRoy W. Alaways ◽  
Sean P. Mish ◽  
Mont Hubbard
Keyword(s):  
Drag Coefficient ◽  
Initial Velocity ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Three Dimensions ◽  
Video Cameras ◽  
High Speed Video ◽  
Position Data ◽  
Estimation Scheme ◽  
The Mean

Pitched-baseball trajectories were measured in three dimensions during competitions at the 1996 Summer Olympic games using two high-speed video cameras and standard DLT techniques. A dynamic model of baseball flight including aerodynamic drag and Magnus lift forces was used to simulate trajectories. This simulation together with the measured trajectory position data constituted the components of an estimation scheme to determine 8 of the 9 release conditions (3 components each of velocity, position, and angular velocity) as well as the mean drag coefficient CD and terminal conditions at home plate. The average pitch loses 5% of its initial velocity during flight. The dependence of estimated drag coefficient on Reynolds number hints at the possibility of the drag crisis occurring in pitched baseballs. Such data may be used to quantify a pitcher’s performance (including fastball speed and amount of curve-ball break) and its improvement or degradation over time. It may also be used to understand the effects of release parameters on baseball trajectories.

scholarly journals Standard of the Initial Ball Velocity for a Fly Ball in Baseball Hitting

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 137
Author(s):  
Hirotaka Nakashima ◽  
Gen Horiuchi ◽  
Shinji Sakurai
Keyword(s):  
Initial Velocity ◽  
High Speed ◽  
Baseball Players ◽  
Ball Impact ◽  
Video Cameras ◽  
High Speed Video ◽  
Before And After ◽  
Ball Velocity ◽  
Opposite Field ◽  
Measuring Tape

This study aimed to determine the minimum required initial velocity to hit a fly ball toward the same field (left-field for right-handed batters), center field, and opposite field (right field for right-handed batters). Six baseball players hit fastballs launched by a pitching machine. The movements of the balls before and after bat-to-ball impact were recorded using two high-speed video cameras. The flight distance was determined using a measuring tape. Seventy-nine trials were analyzed, and the minimum required initial velocities of batted balls were quantified to hit balls 60, 70, 80, 90, 100, 110, and 120 m in each direction through regression analysis. As a result, to hit a ball 120 m, initial velocities of 43.0, 43.9, and 46.0 m/s were required for the same field, center field, and opposite field, respectively. The result provides a useful index for batters to hit a fly ball in each of the directions.

scholarly journals Illustrating a free, open-source method for quantifying locomotor performance with sprinting Aegean wall lizards

2014 ◽  
Author(s):  
Colin Donihue ◽  
Ben Kazez
Keyword(s):  
Natural History ◽  
Open Source ◽  
High Speed ◽  
Video Data ◽  
Locomotor Performance ◽  
Analysis Program ◽  
Video Cameras ◽  
High Speed Video ◽  
Position Data ◽  
Free Open Source

Locomotion is an important characteristic of many animals’ natural history. With the increasing availability of high-speed video cameras, videography is a powerful tool for analyzing fast or subtle motions with unprecedented resolution. However, the programs currently available for analyzing these videos are either dauntingly time intensive or prohibitively expensive. We have developed a free, open-source video analysis program, SAVRA, that enables the quick capture of scaled position data. Here we demonstrate its use with an analysis of several videos of the Aegean wall lizard (Podarcis erhardii). We hope making this program freely available will facilitate the analysis of video data across taxa, not just in laboratory settings but also in natural contexts.

Characteristics of Spatter in Micro-Drilling of Metal Sheet by Pulsed Nd:YAG Laser

2016 ◽  
Vol 10 (6) ◽  
pp. 874-881 ◽  
Author(s):  
Yasuhiro Okamoto ◽  
◽  
Hibiki Yamamoto ◽  
Akira Okada ◽  
Keyword(s):  
Initial Velocity ◽  
High Speed ◽  
Gas Flow ◽  
Thermal Damage ◽  
Drilling Process ◽  
3D Tracking ◽  
Workpiece Surface ◽  
Video Cameras ◽  
High Speed Video ◽  
Micro Drilling

In laser cutting and drilling process, molten material was scattered as spatter, which deteriorates the surface integrity of a workpiece because of the thermal damage. It is expected that the control of assist gas flow can reduce the adhesion of spatter. In order to investigate the improvement method of thermal damage due to the adhesion of spatter, it is required to clarify characteristics of spatter. Therefore, a method was developed to collect and analyze spatter based on the use of high-speed video cameras in the laser micro-drilling process, and the characteristics of spatter movement were numerically investigated by CFD analysis. The scattering velocity and angle of the spatter were investigated by recognizing and tracking spatter with the high-speed video observation. The movement of spatter was observed by using two high-speed video cameras, and analyzed by using a two-direction tracking method, in which the 3D tracking lines of spatter particles were reconstructed in the forward and backward frames, and the actual trajectory of individual spatter particle was obtained by averaging those tracking lines. These measurements revealed that the initial velocity of spatter was mainly distributed from 52 m/s to 200 m/s with an average velocity of 129 m/s. The initial angle of spatter was mainly distributed between 0 and 30 degrees from the workpiece surface in the upward direction. There was little correlation between the initial velocity and angle of spatter. The diameter of spatter was mainly distributed from 1μm to 4μm with an average diameter of 3.7μm. It is important to use the processing conditions achieving the smaller spatter diameter in order to reduce the thermal damage caused by spatter. Although coaxial assist gas flow has an influence on the spatter behavior, that time period is very short. Therefore, it is important to control the spatter behavior outside of the coaxial assist gas flow by using an additional gas flow to prevent the thermal damage to the workpiece surface.

scholarly journals Illustrating a free, open-source method for quantifying locomotor performance with sprinting Aegean wall lizards

2014 ◽  
Author(s):  
Colin Donihue ◽  
Ben Kazez
Keyword(s):  
Natural History ◽  
Open Source ◽  
High Speed ◽  
Video Data ◽  
Locomotor Performance ◽  
Analysis Program ◽  
Video Cameras ◽  
High Speed Video ◽  
Position Data ◽  
Free Open Source

Locomotion is an important characteristic of many animals’ natural history. With the increasing availability of high-speed video cameras, videography is a powerful tool for analyzing fast or subtle motions with unprecedented resolution. However, the programs currently available for analyzing these videos are either dauntingly time intensive or prohibitively expensive. We have developed a free, open-source video analysis program, SAVRA, that enables the quick capture of scaled position data. Here we demonstrate its use with an analysis of several videos of the Aegean wall lizard (Podarcis erhardii). We hope making this program freely available will facilitate the analysis of video data across taxa, not just in laboratory settings but also in natural contexts.

scholarly journals Interaction between an aerodynamically driven, wall-bound drop and a single groove

2020 ◽  
Vol 229 (10) ◽  
pp. 1757-1769 ◽  
Author(s):  
Patrick M. Seiler ◽  
Ilia V. Roisman ◽  
Cameron Tropea
Keyword(s):  
Channel Flow ◽  
Drag Force ◽  
High Speed ◽  
Adhesion Force ◽  
Aerodynamic Drag ◽  
Rear Side ◽  
Threshold Condition ◽  
High Speed Video ◽  
Gravity Forces ◽  
Typical Time

Abstract The interaction between an air-driven, wall-bound drop and a groove in the wall of a channel flow has been investigated experimentally using a high-speed video system. Three major outcomes of drop interaction with the groove are observed: (i) the drop passes over the groove, (ii) the drop is immediately fully captured in the groove or (iii) the drop is captured after first wetting the rear side of the groove. The mechanisms leading to these different outcomes are governed by the aerodynamic drag force, by inertial and gravity forces, and by the adhesion force associated with the substrate wettability. A threshold condition for drop capture is developed, based on the ratio of the typical time for drop passage over the groove to the time for the drop to be sucked into the groove. It has been shown that the probability for drop capture increases for higher Bond numbers.

A new moving model test method for the measurement of aerodynamic drag coefficient of high-speed trains based on machine vision

2017 ◽  
Vol 232 (5) ◽  
pp. 1425-1436 ◽  
Author(s):  
Zhiwei Li ◽  
Mingzhi Yang ◽  
Sha Huang ◽  
Dan Zhou
Keyword(s):  
Machine Vision ◽  
Drag Coefficient ◽  
Model Test ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Full Scale ◽  
Test Method ◽  
Test Accuracy ◽  
Friction Resistance ◽  
Aerodynamic Drag Coefficient

A moving model test method has been proposed to measure the aerodynamic drag coefficient of a high-speed train based on machine vision technology. The total resistance can be expressed as the track friction resistance and the aerodynamic drag according to Davis equation. Cameras are set on one side of the track to capture the pictures of the train, from which the line marks on the side surface of the train are extracted and analyzed to calculate the speed and acceleration of the train. According to Newton’s second law, the aerodynamic drag coefficient can be resolved through multiple tests at different train speeds. Comparisons are carried out with the full-scale coasting test, wind tunnel test, and numerical simulation; good agreement is obtained between the moving model test and the full-scale field coasting test with difference within 1.51%, which verifies that the method proposed in this paper is feasible and reliable. This method can accurately simulate the relative movement between the train, air, and ground. The non-contact measurement characteristic will increase the test accuracy, providing a new experimental method for the aerodynamic measurement.

Aerodynamic Drag on Vehicles in Tunnels

1969 ◽  
Vol 91 (4) ◽  
pp. 694-706 ◽  
Author(s):  
S. William Gouse ◽  
B. S. Noyes ◽  
J. K. Nwude ◽  
M. C. Swarden
Keyword(s):  
Laminar Flow ◽  
Drag Coefficient ◽  
Surface Area ◽  
Incompressible Flow ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Diameter Ratio ◽  
Infinite Body ◽  
Tunnel Wall ◽  
Wetted Surface Area

The purpose of this study was to investigate the aerodynamic drag on vehicles moving in guideways of varying degrees of enclosure. The reason for this study was that several potential high speed ground transport system concepts involve high speed motion of vehicles in enclosed guideways for significant portions of their travel time. Analytical and experimental investigations have been carried out. The analytical studies developed the solution for the aerodynamic drag on a vehicle in an enclosed guideway in laminar flow. The analysis is based on an analogy between the governing equations for the unsteady flow resulting when an infinite body is started impulsively from rest and the steady flow that results from steady motion of a semi-infinite body. The results of this analysis for laminar flow provided a base from which to begin in turbulent flow and were used to justify the basing of a drag coefficient on the wetted surface area of a vehicle rather than the frontal area of a vehicle. Preliminary experiments were executed using spheres as vehicle models. Final experimental studies were carried out using cylindrical models in circular tunnels of various lengths and various degrees of wall porosity. A drop testing apparatus was employed and results were obtained for Reynolds number of the order of 5 · 105. Results to date indicate that for vehicle length-diameter ratios of the order of 15 and above, with tunnel to vehicle diameter ratios of 1.5 and greater, a drag coefficient based on the wetted surface area of the vehicle is independent of the vehicle length-diameter ratio for incompressible flow. Results also indicate that, for incompressible flow, employing a tunnel model with a closed end simulates a tunnel length-diameter ratio of infinity. Tunnel wall porosity, assuming relatively unobstructed motion of fluid outside the porous wall, has a marked effect on decreasing the aerodynamic drag on vehicles moving in enclosed guideways and that for the range of variables investigated (clearance ratio as low as 1.4) tunnel wall porosity of 20 per cent is adequate for all the significant drag reduction that is possible. Qualitative predictions of loss coefficient analytical modeling and literature on transonic flow wind tunnel testing with porous walls are in agreement with the data presented.

scholarly journals Experimental Investigation of Aerodynamic Characteristics of Bat Carcasses after Collision with a Wind Turbine

2019 ◽  
Author(s):  
Shivendra Prakash ◽  
Corey D. Markfort
Keyword(s):  
Drag Coefficient ◽  
High Speed ◽  
Wind Farm ◽  
Time Series Data ◽  
Aerodynamic Drag ◽  
Turbine Blades ◽  
Wind Farms ◽  
Measured Data ◽  
Series Data ◽  
Ballistic Model

Abstract. Large number of bat fatalities have been reported in wind energy facilities in different parts of the world. The wind farm regulators are required to monitor the bat fatalities by conducting carcass survey in the wind farms. Previous studies have implemented ballistic model to characterize the carcass fall zone after strike with turbine blades. Ballistic model contains the aerodynamic drag force term which is dependent upon carcass drag coefficient. The bat carcass drag coefficient is highly uncertain and of which no measurement is available. This manuscript introduces a new methodology for bat carcass drag coefficient estimation. Field investigation at Macksburg wind farm resulted in the discovery of three bat species: Eastern Red bat (Lasiurus borealis), Hoary bat (Lasiurus cinereus) and Evening bat (Nycticeius humeralis). Carcass drop experiments were performed from a dropping platform at finite height and carcass position time series data was recorded using a high-speed camera. Falling carcasses were subjected to aerodynamic drag and gravitational force. Carcasses were observed to undergo rotation; often rotating around multiple axes simultaneously and lateral translation. The carcass complex fall dynamics along with drop from limited height prohibits it from attaining the terminal velocity. Under this limitation, drag coefficient can be estimated by fitting ballistic model to the measured data. A new multivariable optimization algorithm was performed to find the best-fit of the ballistic model to the measured data resulting in an optimized drag coefficient estimate. Sensitivity analysis demonstrated significant variation in drag coefficient with small a change in initial position highlighting the chaotic nature of carcass fall dynamics. Based on the limited sampling, the bat carcass drag coefficient range was found to be between 0.70–1.23.

scholarly journals Experimental analysis of high velocity impacts of composite fragments on aluminium plates

2021 ◽  
Vol 250 ◽  
pp. 01011
Author(s):  
Jorge López-Puente ◽  
Jesús Pernas-Sánchez ◽  
José Alfonso Artero-Guerrero ◽  
David Varas ◽  
Joseba Múgica ◽  
...  
Keyword(s):  
High Velocity ◽  
High Speed ◽  
Woven Composites ◽  
Residual Velocity ◽  
Video Cameras ◽  
High Speed Video ◽  
High Velocity Impacts ◽  
Deformable Structure ◽  
The Impact ◽  
Composite Blades

The improvement of engines is one of the ways to diminish the fuel consumption in civil aircrafts, and Open Rotors engines are one of the best promises in order to achieve a sensible efficiency increment. These engines have large composite blades that could, in the event of failure, impact against the fuselage, totally or partially. In this case, composite fragments could behave as impactors. In order to design fuselages for this event and adopt these new engines in the future, it is necessary to understand the impact behaviour of a composite fragment against a deformable structure. To this end, unidirectional and woven composites fragments were impacted at high velocity (up to 150 m/s) against aluminium panels at different impact velocities. The composite fragments were made using AS4/8552 (UD) and AGP-193PW (woven) prepregs manufactured by Hexcel Composites, both using AS4 fibres and 8552 epoxy matrix. High speed video cameras were used to record the impact process and to measure both the impact and the residual velocity and hence the energy absorbed.

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