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1.
Abstract Our aim was to present a mathematical model of rowing and sculling that allowed for a comparison of oar blade designs. The relative movement between the oar blades and water during the drive phase of the stroke was modelled, and the lift and drag forces generated by this complex interaction were determined. The model was driven by the oar shaft angular velocity about the oarlock in the horizontal plane, and was shown to be valid against measured on-water mean steady-state shell velocity for both a heavyweight men's eight and a lightweight men's single scull. Measured lift and drag force coefficients previously presented by the authors were used as inputs to the model, whichs allowed for the influence of oar blade design on rowing performance to be determined. The commonly used Big Blade, which is curved, and it's flat equivalent were compared, and blade curvature was shown to generate a 1.14% improvement in mean boat velocity, or a 17.1-m lead over 1500 m. With races being won and lost by much smaller margins than this, blade curvature would appear to play a significant role in propulsion. 相似文献
2.
The highly unsteady flow around a rowing blade in motion is examined using a three-dimensional computational fluid dynamics
(CFD) model which accounts for the interaction of the blade with the free surface of the water. The model is validated using
previous experimental results for quarter-scale blades held stationary near the surface in a water flume. Steady-state drag
and lift coefficients from the quarter-scale blade flume simulation are compared to those from a simulation of the more realistic
case of a full-scale blade in open water. The model is then modified to accommodate blade motion by simulating the unsteady
motion of the rowing shell moving through the water, and the sweep of the oar blade with respect to the shell. Qualitatively,
the motion of the free surface around the blade during a stroke shows a realistic agreement with the actual deformation encountered
during rowing. Drag and lift coefficients calculated for the blade during a stroke show that the transient hydrodynamic behaviour
of the blade in motion differs substantially from the stationary case. 相似文献
3.
The aim of the present study was to find a more optimal blade design for rowing performance than the Big Blade, which has been shown to be less than optimal for propulsion. As well as the Big Blade, a flat Big Blade, a flat rectangular blade, and a rectangular blade with the same curvature and projected area as the Big Blade were tested in a water flume to determine their fluid dynamic characteristics at the full range of angles at which the oar blade might present itself to the water. Similarities were observed between the flat Big Blade and rectangular blades. However, the curved rectangular blade generated significantly more lift in the angle range 0-90 degrees than the curved Big Blade, although it was similar between 90 and 180 degrees. This difference was attributed to the shape of the upper and lower edges of the blade and their influence on the fluid flow around the blade. Although the influence of oar blade design on boat speed was not investigated here, the significant increases in fluid force coefficients for the curved rectangular blade suggest that this new oar blade design could elicit a practically significant improvement in rowing performance. 相似文献
4.
Abstract The aim of the present study was to find a more optimal blade design for rowing performance than the Big Blade, which has been shown to be less than optimal for propulsion. As well as the Big Blade, a flat Big Blade, a flat rectangular blade, and a rectangular blade with the same curvature and projected area as the Big Blade were tested in a water flume to determine their fluid dynamic characteristics at the full range of angles at which the oar blade might present itself to the water. Similarities were observed between the flat Big Blade and rectangular blades. However, the curved rectangular blade generated significantly more lift in the angle range 0 – 90° than the curved Big Blade, although it was similar between 90 and 180°. This difference was attributed to the shape of the upper and lower edges of the blade and their influence on the fluid flow around the blade. Although the influence of oar blade design on boat speed was not investigated here, the significant increases in fluid force coefficients for the curved rectangular blade suggest that this new oar blade design could elicit a practically significant improvement in rowing performance. 相似文献
5.
The purpose of this investigation was to examine the fluid dynamic characteristics of the two most commonly used oar blades: the Big Blade and the Macon. Scaled models of each blade, as well as a flat Big Blade, were tested in a water flume using a quasi-static method similar to that used in swimming and kayaking research. Measurement of the normal and tangential blade forces enabled lift and drag forces generated by the oar blades to be calculated over the full range of sweep angles observed during a rowing stroke. Lift and drag force coefficients were then calculated and compared between blades. The results showed that the Big Blade and Macon oar blades exhibited very similar characteristics. Hydraulic blade efficiency was not therefore found to be the reason for claims that the Big Blade could elicit a 2% improvement in performance over the Macon. The Big Blade was also shown to have similar characteristics to the flat plate when the angle of attack was below 90 degrees , despite significant increases in the lift coefficient when the angle of attack increased above 90 degrees . This result suggests that the Big Blade design may not be completely optimized over the whole stroke. 相似文献
6.
Abstract The purpose of this investigation was to examine the fluid dynamic characteristics of the two most commonly used oar blades: the Big Blade and the Macon. Scaled models of each blade, as well as a flat Big Blade, were tested in a water flume using a quasi-static method similar to that used in swimming and kayaking research. Measurement of the normal and tangential blade forces enabled lift and drag forces generated by the oar blades to be calculated over the full range of sweep angles observed during a rowing stroke. Lift and drag force coefficients were then calculated and compared between blades. The results showed that the Big Blade and Macon oar blades exhibited very similar characteristics. Hydraulic blade efficiency was not therefore found to be the reason for claims that the Big Blade could elicit a 2% improvement in performance over the Macon. The Big Blade was also shown to have similar characteristics to the flat plate when the angle of attack was below 90°, despite significant increases in the lift coefficient when the angle of attack increased above 90°. This result suggests that the Big Blade design may not be completely optimized over the whole stroke. 相似文献
7.
A. Millward 《Journal of sports sciences》2013,31(2):93-103
A model of the motion of a single‐scull rowing hull has been developed and verified against rowing performance data. The model was then used to explore the effect of changes in the cyclic rowing force on the boat speed. The calculations have shown that the shape of the rowing force curve and the proportion of recovery time in the total stroke can have an important effect on the boat speed. It has also been shown that a study of the fluid mechanics of the oar blade would be advantageous in determining whether a reduction in the power wasted can be obtained by changing the ratio of rowing force to normal force. 相似文献
8.
A Millward 《Journal of sports sciences》1987,5(2):93-103
A model of the motion of a single-scull rowing hull has been developed and verified against rowing performance data. The model was then used to explore the effect of changes in the cyclic rowing force on the boat speed. The calculations have shown that the shape of the rowing force curve and the proportion of recovery time in the total stroke can have an important effect on the boat speed. It has also been shown that a study of the fluid mechanics of the oar blade would be advantageous in determining whether a reduction in the power wasted can be obtained by changing the ratio of rowing force to normal force. 相似文献
9.
Brock Laschowski Cameron C. Hopkins John R. de Bruyn Volker Nolte 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(1):76-86
The deflection of rowing oar shafts subjected to a static load was investigated. Two sets of sculling oars of different design stiffness were tested at three different lengths from 2.66 to 2.70 m. Loads up to 201 N were applied to the blade end of the oar shafts, and deflections were measured at six positions along the length of the shafts. The experimental results were compared with theoretical predictions obtained by modelling the oar shafts as homogenous end-loaded cantilever beams. The results show that the oar shafts are not uniform, in contradiction to the assumed model, but rather are most compliant near the sleeves and up to 80% stiffer towards the blades. The effect of oar shaft stiffness and length on the deflection angle at the blade end of the oar shaft was at most 1.18 ± 0.01°. The measured variation of stiffness along the shaft has implications for boat propulsion and rowing performance. 相似文献
10.
Lotte L. Lintmeijer Mathijs J. Hofmijster Guido A. Schulte Fischedick Patrick J. Zijlstra A. J. “Knoek” Van Soest 《Journal of sports sciences》2018,36(18):2138-2146
In rowing, mechanical power output is a key parameter for biophysical analyses and performance monitoring and should therefore be measured accurately. It is common practice to estimate on-water power output as the time average of the dot product of the moment of the handle force relative to the oar pin and the oar angular velocity. In a theoretical analysis we have recently shown that this measure differs from the true power output by an amount that equals the mean of the rower’s mass multiplied by the rower’s center of mass acceleration and the velocity of the boat. In this study we investigated the difference between a rower’s power output calculated using the common proxy and the true power output under different rowing conditions. Nine rowers participated in an on-water experiment consisting of 7 trials in a single scull. Stroke rate, technique and forces applied to the oar were varied. On average, rowers’ power output was underestimated with 12.3% when determined using the common proxy. Variations between rowers and rowing conditions were small (SD = 1.1%) and mostly due to differences in stroke rate. To analyze and monitor rowing performance accurately, a correction of the determination of rowers’ on-water power output is therefore required. 相似文献
11.
Abstract In rowing, power is inevitably lost as kinetic energy is imparted to the water during push-off with the blades. Power loss is estimated from reconstructed blade kinetics and kinematics. Traditionally, it is assumed that the oar is completely rigid and that force acts strictly perpendicular to the blade. The aim of the present study was to evaluate how reconstructed blade kinematics, kinetics, and average power loss are affected by these assumptions. A calibration experiment with instrumented oars and oarlocks was performed to establish relations between measured signals and oar deformation and blade force. Next, an on-water experiment was performed with a single female world-class rower rowing at constant racing pace in an instrumented scull. Blade kinematics, kinetics, and power loss under different assumptions (rigid versus deformable oars; absence or presence of a blade force component parallel to the oar) were reconstructed. Estimated power losses at the blades are 18% higher when parallel blade force is incorporated. Incorporating oar deformation affects reconstructed blade kinematics and instantaneous power loss, but has no effect on estimation of power losses at the blades. Assumptions on oar deformation and blade force direction have implications for the reconstructed blade kinetics and kinematics. Neglecting parallel blade forces leads to a substantial underestimation of power losses at the blades. 相似文献
12.
赛艇运动中拉桨阶段的桨力曲线反映了运动员的发力特征，是专项竞技能力诊断的重要途径。根据国家队的测试实例，对不同艇种、不同桨位的桨力曲线特征进行归纳分析总结，对赛艇项目进行系列测试（桨频：35桨/min），结合专项认为专项技术较好的多人艇运动员大多采用A型；双人单桨项目中．领桨手倾向于采用A型桨力-时间曲线，一号位桨手倾向于采用B型桨力-时间曲线。不同桨频下的桨力-时间曲线特征可作为训练效果的评估依据，低桨频训练必须保持合理的拉桨速度和拉桨力量。 相似文献
13.
Comparison of force-related performance indicators between heavyweight and lightweight rowers 总被引：1，自引：0，他引：1
Doyle MM Lyttle A Elliott B 《Sports biomechanics / International Society of Biomechanics in Sports》2010,9(3):178-192
The aim of this study was to examine biomechanical variables relating to the force production of men's Lightweight (LW) and Heavyweight (HW) rowing pairs. Seven HW and seven LW coxless pairs were studied under a range of stroke rates, from 20 spm to race rating (average of 33.7 spm for the HWs and 33.9 spm for the LWs). Each crew was equipped with biomechanical apparatus allowing the measurement of gate force, horizontal oar angle, and boat velocity. The HW crews exhibited significantly higher (p < 0.05) values for all variables examined, at all rates. Peak handle force was 26.2% to 30.2% higher in the HW group. Average handle force ranged from 18.7% to 22.1% higher than the LW group. Work per stroke was found to be 26% to 28% higher for the HW crews, and Power Per Kilogram was also greater for the HW crews, from 24.0% to 29.2%. The LWs were observed to be consistently, but not significantly, slower than the HWs (from 96.9% at the race situation, to 98.7% at 28 spm). These observations are important when considering biomechanical performance indicators in rowing, as significant changes in performance indicators may lead to only minimal alteration in boat velocity. 相似文献
14.
Mathijs J. Hofmijster Lotte L. Lintmeijer Peter J. Beek A. J. Knoek van Soest 《Journal of sports sciences》2018,36(18):2147-2153
Mechanical power output is a key performance-determining variable in many cyclic sports. In rowing, instantaneous power output is commonly determined as the dot product of handle force moment and oar angular velocity. The aim of this study was to show that this commonly used proxy is theoretically flawed and to provide an indication of the magnitude of the error. To obtain a consistent dataset, simulations were performed using a previously proposed forward dynamical model. Inputs were previously recorded rower kinematics and horizontal oar angle, at 20 and 32 strokes?min?1. From simulation outputs, true power output and power output according to the common proxy were calculated. The error when using the common proxy was quantified as the difference between the average power output according to the proxy and the true average power output (P?residual), and as the ratio of this difference to the true average power output (ratiores./rower). At stroke rate 20, P?residual was 27.4 W and ratiores./rower was 0.143; at stroke rate 32, P?residual was 44.3 W and ratiores./rower was 0.142. Power output in rowing appears to be underestimated when calculated according to the common proxy. Simulations suggest this error to be at least 10% of the true power output. 相似文献
15.
16.
通过定点定焦和跟踪拍摄,对参加2007"好运北京"测试赛的中外优秀运动员进行拍摄.运用SIMI软件进行分析,对我国运动员的在体力分配,桨频、划距上与国外运动员进行对比.分析桨出水瞬时速度存在一定差异,我国运动员在桨出水瞬间速度达到最小值,并且比冠亚军低很多,回桨阶段时间比例过大,导致艇速速度差比较大. 相似文献
17.
A mathematical model relating power output of rower to stroke rate on an ergometer (the Concept II Indoor Rower TM, Model
C) is studied. The model is used to analyse the ergometer performance of a particular rower. It is determined that he can
be more efficient (i.e. decrease power output while maintaining fixed velocity) by decreasing stroke rate, but at the expense
of increasing force during the drive. It is also shown that he can be more efficient by increasing the drag factor (using
higher vent setting) without increasing force. Dependence of power output on rowing style (the shape of the force curve) is
also examined. It is shown that variation of force during the drive has little effect on efficiency, but efficiency is reduced
by asymmetry of the force curve that favours the legs. 相似文献
18.
Elliott B Lyttle A Birkett O 《Sports biomechanics / International Society of Biomechanics in Sports》2002,1(2):123-134
The purpose of this study was to compare rowing technique on the dynamic RowPerfect ergometer with a single scull. Eight national-level rowers performed on both the RowPerfect ergometer and in a single scull over 500 m, at rates of 24, 26, and 28 strokes/minute. Blade force and oar angle (on-water) and handle force and stroke length (on the ergometer) were measured. Both force and stroke angle/length were normalised from 0 to 100 (where 100 was the peak value). Body positions of the subjects at both the catch and finish of each of these rowing strokes were also compared for each stroke rate. The coefficient of multiple determination (CMD) was used to measure the consistency of force curves over a sample of five sequential strokes for each rower. Cross-correlations were performed between the left- and right-side on-water sculling force curves and a mean of these values with the ergometer curve for each rower. Stroke angle/length, which did not vary with rate, was similar for both forms of rowing. The CMDs showed a high consistency across the normalised strokes of each subject (approximately 0.98). Cross-correlation values of 0.91, 0.92, and 0.93 were recorded between the force curves from the ergometer and on-water trials for stroke rates of 24, 26, and 28 strokes/minute, respectively. The mean trunk, thigh and lower leg angles at the catch and finish of the stroke were also similar across the stroke rates as determined by t-tests. Results indicate that technique used on the RowPerfect ergometer was similar to that for on-water sculling, thus validating its use in off-water training. 相似文献
19.
赛艇技术的生物力学研究 总被引：1，自引：0，他引：1
使用赛艇多参数遥测分析系统和IPL型高速摄影机同步测试方法,对我国国家赛艇集训队16名高水平运动员(男10,女6)的双桨技术进行了测试研究,分析结果如下:①在三种划桨类型中,“平缓力型”的动力学效率最高。“平缓力型”意味着拉桨力平稳增长达到峰值,然后对称下降直至拉桨结束。②艇速曲线有“单峰型”和“双峰型”两种类型。“单峰型”的特点是艇速变化平稳、能量消耗较少;“双峰型”能量消耗多。出现“双峰型”的主要原因是没有“边拉边按”和运动员身体在滑轨上加速不稳。③建立了浆力有效冲量与艇平均速度、艇速波动程度关系式。④发现一些选手左右手划桨力差别较大,桨叶入水角偏小和“拉提”时拉的不够等问题。 相似文献
20.
Barry Bixler David Pease Fiona Fairhurst 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):81-98
The aim of this study was to build an accurate computer-based model to study the water flow and drag force characteristics around and acting upon the human body while in a submerged streamlined position. Comparisons of total drag force were performed between an actual swimmer, a virtual computational fluid dynamics (CFD) model of the swimmer, and an actual mannequin based on the virtual model. Drag forces were determined for velocities between 1.5 m/s and 2.25 m/s (representative of the velocities demonstrated in elite competition). The drag forces calculated from the virtual model using CFD were found to be within 4% of the experimentally determined values for the mannequin. The mannequin drag was found to be 18% less than the drag of the swimmer at each velocity examined. This study has determined the accuracy of using CFD for the analysis of the hydrodynamics of swimming and has allowed for the improved understanding of the relative contributions of various forms of drag to the total drag force experienced by submerged swimmers. 相似文献