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1.
The understanding and development of cycling aerodynamics 总被引：1，自引：1，他引：0
In elite cycling the resistive force is dominated by aerodynamics. Be it on the roads or in the velodrome, the sport has many
examples where aerodynamics has won and lost races. Since the invention of the bicycle, engineers have strived to improve
performance, often by reducing aerodynamic drag. Over the last 50 years a number of authors have presented their efforts in
journals, books and magazines. This review summarises the publications that show the continued development in the aerodynamics
of cycling. The review concludes by examining the shortcomings of the current understanding and making suggestions for future
research and development. 相似文献
2.
Aerodynamic drag in cycling: methods of assessment 总被引：1，自引：0，他引：1
Debraux P Grappe F Manolova AV Bertucci W 《Sports biomechanics / International Society of Biomechanics in Sports》2011,10(3):197-218
When cycling on level ground at a speed greater than 14 m/s, aerodynamic drag is the most important resistive force. About 90% of the total mechanical power output is necessary to overcome it. Aerodynamic drag is mainly affected by the effective frontal area which is the product of the projected frontal area and the coefficient of drag. The effective frontal area represents the position of the cyclist on the bicycle and the aerodynamics of the cyclist-bicycle system in this position. In order to optimise performance, estimation of these parameters is necessary. The aim of this study is to describe and comment on the methods used during the last 30 years for the evaluation of the effective frontal area and the projected frontal area in cycling, in both laboratory and actual conditions. Most of the field methods are not expensive and can be realised with few materials, providing valid results in comparison with the reference method in aerodynamics, the wind tunnel. Finally, knowledge of these parameters can be useful in practice or to create theoretical models of cycling performance. 相似文献
3.
Pierre Debraux Frederic Grappe Aneliya V. Manolova William Bertucci 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):197-218
When cycling on level ground at a speed greater than 14 m/s, aerodynamic drag is the most important resistive force. About 90% of the total mechanical power output is necessary to overcome it. Aerodynamic drag is mainly affected by the effective frontal area which is the product of the projected frontal area and the coefficient of drag. The effective frontal area represents the position of the cyclist on the bicycle and the aerodynamics of the cyclist-bicycle system in this position. In order to optimise performance, estimation of these parameters is necessary. The aim of this study is to describe and comment on the methods used during the last 30 years for the evaluation of the effective frontal area and the projected frontal area in cycling, in both laboratory and actual conditions. Most of the field methods are not expensive and can be realised with few materials, providing valid results in comparison with the reference method in aerodynamics, the wind tunnel. Finally, knowledge of these parameters can be useful in practice or to create theoretical models of cycling performance. 相似文献
4.
目的:探讨环境风对跳台滑雪空中飞行气动特性的影响。方法:通过计算流体力学(computational fluid dynamics,CFD)方法数值模拟预测了不同环境风下跳台滑雪空中飞行空气动力学特性,并探究了水平方向环境风、竖直方向环境风以及侧向环境风对气动特性的影响。将跳台滑雪运动员与滑雪板看成一个多体系统,建立在空中飞行某一种普遍姿态下此多体系统的精细化三维几何模型与网格模型,采用部分时均(partially averaged Navier-Stokes,PANS)湍流模型进行数值模拟,提取多体系统的受力及力矩情况,直观地显示多体系统周围的流场信息。数值预测涉及的水平方向风风速包括-4 m/s、-2.5 m/s、-1 m/s、0 m/s、1 m/s、2.5 m/s、4 m/s等工况;竖直方向风风速包括-8 m/s、-4 m/s、-2.5 m/s、-1 m/s、0 m/s、1 m/s、2.5 m/s、4 m/s、8 m/s等工况;侧向风风速包括1.5 m/s、3.0 m/s、4.5 m/s、7.5 m/s、10.5 m/s、13.5 m/s等工况。结果:1)水平方向环境风下多体系统升力、阻力以及俯仰力矩变化明显,与风速呈现近似线性关系,同时水平逆风情况下力学特性数值结果的增长速度大于水平顺风情况下力学特性数值结果的减小速度;2)在竖直方向风速较小时(小于2.5 m/s),升力、阻力以及俯仰力矩增加缓慢,在竖直方向风速较大时(大于4 m/s),升力、阻力以及俯仰力矩开始相对快速增加,同时,竖直向上环境风使得升力、阻力、俯仰力矩增大,竖直向下环境风使得升力、阻力以及俯仰力矩减小,而且竖直向上环境风情况下增长幅度明显小于竖直向下环境风情况下减少幅度;3)侧向环境风产生偏航力、偏航力矩、翻滚力矩,同时,侧向环境风对运动员的升力、阻力以及俯仰力矩产生影响。在风速较小(小于3 m/s)时,这些力和力矩很小,在风速较大(大于4.5 m/s)时,比较明显。结论:1)水平方向环境风对跳台滑雪空中飞行气动特性的影响非常明显,相较而言,竖直方向环境风和侧向环境风对空中飞行气动特性的影响小很多,但侧向环境风的影响情况较为复杂,对多体系统产生较为明显的偏航力、偏航力矩、翻滚力矩;2)环境风对跳台滑雪空中飞行气动特性的影响机理能够为比赛临场预判与决策提供有效的辅助支持,也为运动员空中飞行稳定性控制与技术训练提供科学指导。 相似文献
5.
Flight dynamics of an American football in a forward pass 总被引：2，自引：2，他引：0
The motion of an American football in a forward pass is discussed in this paper. It was investigated by using wind-tunnel
aerodynamic data in a numerical integration of the full nonlinear equations of motion, and by application of the small-angle
theory for the atmospheric motion of an axisymmetric spinning body. The numerical simulations agree with certain observed
features such as the range, flight duration, and ratio of the spin and precession frequencies. The analytic results reveal
functional dependences of the flight parameters on the aerodynamics and give insights into the physical effects that occur.
Both approaches show a feature that is known as ‘drift’ in the science of ballistics, namely that a long, highly arched trajectory
of a spinning body does not lie in a vertical plane, but rather turns slightly to the left or right, depending on the direction
of the spin vector and on the magnitudes of the aerodynamic loads. 相似文献
6.
Aerodynamics has such a profound impact on cycling performance at the elite level that it has infiltrated almost every aspect of the sport from riding position and styles, equipment design and selection, race tactics and training regimes, governing rules and regulations to even the design of new velodromes. This paper presents a review of the aspects of aerodynamics that are critical to understanding flows around cyclists under racing conditions, and the methods used to evaluate and improve aerodynamic performance at the elite level. The fundamental flow physics of bluff body aerodynamics and the mechanisms by which the aerodynamic forces are imparted on cyclists are described. Both experimental and numerical techniques used to investigate cycling aerodynamic performance and the constraints on implementing aerodynamic saving measures at the elite level are also discussed. The review reveals that the nature of cycling flow fields are complex and multi-faceted as a result of the highly three-dimensional and variable geometry of the human form, the unsteady racing environment flow field, and the non-linear interactions that are inherent to all cycling flows. Current findings in this field have and will continue to evolve the sport of elite cycling while also posing a multitude of potentially fruitful areas of research for further gains in cycling performance. 相似文献
7.
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
8.
Bixler B Pease D Fairhurst F 《Sports biomechanics / International Society of Biomechanics in Sports》2007,6(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
9.
A badminton shuttlecock flies in a high-drag, and thus, the sport has been a subject of research from the point of view of aerodynamics. A badminton shuttlecock generates significant aerodynamic drag and has a complex flight trajectory. It also has the smallest ballistic coefficient and exhibits the largest in-flight deceleration of any airborne sporting projectile. The ballistic coefficient of a projectile is a measure of its ability to overcome air resistance in flight and is inversely proportional to deceleration. The primary objectives of this study were to measure the aerodynamic properties of feather shuttlecocks under a range of the wind speed (10–60 m/s) and pitch angle (0°–25°). In particular, measurements of aerodynamic forces were performed at high Reynolds numbers (more than Re = 210,000), and the effect of shuttlecock deformation on aerodynamic properties was also investigated, because it is presumed that the flight dynamics is affected by the deformation of the shuttlecock skirt. A shuttlecock skirt is composed of an array of diverging stems, the ends of which are at the convergent end of the skirt, joined together in an end ring. The shuttlecock rotates about its major axis in actual flight, and thus, the experiments were performed on shuttlecocks with and without rotation (spin). Furthermore, the effect of the flow passing through the gaps between the slots (stiffeners) located at the leg portion of the shuttlecock skirt on aerodynamic characteristics is demonstrated by means of a shuttlecock model without gaps, which was completely covered with cellophane tape. The free rotation rate of a shuttlecock increased with an increase in the Reynolds number, and the drag coefficient gradually decreased above Re = 86,000 for a non-rotating shuttlecock. The reduction of drag can be explained by the deformation of the skirt observed in wind tunnel experiments at high speed. In this study, for a rotating shuttlecock, a reduction of drag was not observed over a whole range of Reynolds numbers, because deformation of the skirt for a rotating shuttlecock becomes smaller than that for a non-rotating shuttlecock. However, there was no significant difference in drag coefficient between rotating and non-rotating shuttlecocks, in contrast to the difference in drag coefficient between shuttlecocks with and without gaps. The drag coefficient for a shuttlecock without gaps was significantly smaller than that for a standard shuttlecock (with gaps). For a standard shuttlecock, the air flowed through the gaps into the shuttlecock skirt, and this flow was related to high aerodynamic drag. 相似文献
10.
Dimitri Nicolopoulos Eric Berton Guillaume Gouvernet André Jacques 《Sports Engineering》2009,11(4):177-185
A method aimed at the development of an America’s Cup racing yacht bulb is developed and validated against experimental data.
The method relies heavily on Reynolds Averaged Navier Stokes computational fluid dynamics (CFD) and also factors in gravitational
and aerodynamics effects through the use of a Velocity Prediction Program. Initial extensive use of towing tank results is
made to be able to validate the CFD solution and thus develop a solid ground for predictive work. Then, in order to narrow
down the focus on bulb developments, decoupled hypotheses are made on the influence of the hull and free surface wave. The
development of a detailed performance analysis chart of a known base bulb allows the use of a relatively small series of CFD
simulations together with physical hypotheses to assess any given bulb performance relative to the known base. The discussion
of the results on a specific development highlights the promises and limitations of the method; final full scale results are
discussed and analysed as well. 相似文献
11.
In time trial cycling stage, aerodynamic properties of cyclists are one of the main factors that determine performances. Such
aerodynamic properties are strongly dependent on the cyclist ability to get into the most suitable posture to have minimal
projected frontal area facing the air. The accurate knowledge of the projected frontal area (A) is thus of interest to understand the performance better. This study aims for the first time at a model estimating accurately
A as a function of anthropometric properties, postural variations of the cyclist and the helmet characteristics. From experiments
carried out in a wind tunnel test-section, drag force measurements, 3D motion analysis and frontal view of the cyclists are
performed. Computerized planimetry measurements of A are then matched with factors related to the cyclist posture and the helmet inclination and length. Data show that A can be fully represented by a rate of the cyclist body height, his body mass, inclination and length of his helmet. All the
above-mentioned factors are thus taken into account in the present modelling and the prediction accuracy is then determined
by comparisons between planimetry measurements and A values estimated using the model. 相似文献
12.
Badminton synthetic shuttlecocks are known to have significantly different aerodynamic behaviours compared to feathered shuttlecocks due to the difference in designs and use of materials. Given the fragility of avian feathers used for feathered shuttlecocks and the constantly increasing cost of purchase, the interest to assess the current synthetic shuttlecock design as a feasible alternative has re-emerged. The single-piece injection-moulded synthetic shuttlecock has been the mainstream design for the past 50 years; however, little evidence has supported that the design mimics the aerodynamics of feathered shuttlecocks. Recently, a two-part skirt design has emerged proclaiming to have surpassed its synthetic predecessor in regard to matching the aerodynamics of feathered shuttlecocks. In the current study, two different synthetic designs (injection-moulded vs two-part skirt) were benchmarked against a feathered shuttlecock. A wind tunnel test was conducted between 30 and 145 km/h. The drag coefficients of both synthetic shuttlecocks were similar to the feathered shuttlecock up to 105 km/h. Thereafter, the drag coefficient of the injection-moulded design dropped from 0.62 to 0.5 and showing no signs of levelling at speeds over 105 km/h, while the coefficient for two-part skirt design stabilised at approximately 0.55. It was concluded that the two-part skirt design better mimicked the aerodynamics of the feathered shuttlecock. 相似文献
13.
García-López J Rodríguez-Marroyo JA Juneau CE Peleteiro J Martínez AC Villa JG 《Journal of sports sciences》2008,26(3):277-286
The aims of this study were to measure the aerodynamic drag in professional cyclists, to obtain aerodynamic drag reference values in static and effort positions, to improve the cyclists' aerodynamic drag by modifying their position and cycle equipment, and to evaluate the advantages and disadvantages of these modifications. The study was performed in a wind tunnel with five professional cyclists. Four positions were assessed with a time-trial bike and one position with a standard racing bike. In all positions, aerodynamic drag and kinematic variables were recorded. The drag area for the time-trial bike was 31% higher in the effort than static position, and lower than for the standard racing bike. Changes in the cyclists' position decreased the aerodynamic drag by 14%. The aero-helmet was not favourable for all cyclists. The reliability of aerodynamic drag measures in the wind tunnel was high (r > 0.96, coefficient of variation < 2%). In conclusion, we measured and improved the aerodynamic drag in professional cyclists. Our results were better than those of other researchers who did not assess aerodynamic drag during effort at race pace and who employed different wheels. The efficiency of the aero-helmet, and the validity, reliability, and sensitivity of the wind tunnel and aerodynamic field testing were addressed. 相似文献
14.
Recumbent bicycles (RB) are high performance, human-powered vehicles. In comparison to normal/upright bicycles (NB) the RB may allow individuals to reach higher speeds due to aerodynamic advantages. The purpose of this investigation was to compare the non-aerodynamic factors that may potentially influence the performance of the two bicycles. 3D body centre of mass (BCoM) trajectory, its symmetries, and the components of the total mechanical work necessary to sustain cycling were assessed through 3D kinematics and computer simulations. Data collected at 50, 70, 90 110 rpm during stationary cycling were used to drive musculoskeletal modelling simulation and estimate muscle-tendon length. Results demonstrated that BCoM trajectory, confined in a 15-mm side cube, changed its orientation, maintaining a similar pattern across all cadences in both bicycles. RB displayed a reduced additional mechanical external power (16.1 ± 9.7 W on RB vs. 20.3 ± 8.8 W on NB), a greater symmetry on the progression axis, and no differences in the internal mechanical power compared to NB. Simulated muscle activity revealed small significant differences for only selected muscles. On the RB, quadriceps and gluteus demonstrated greater shortening, while biceps femoris, iliacus, and psoas exhibited greater stretch; however, aerodynamics still remains the principal benefit. 相似文献
15.
Thomas Peeters Jochen Vleugels Raman Garimella Steven Truijen Wim Saeys Stijn Verwulgen 《Journal of sports sciences》2020,38(19):2193-2199
ABSTRACT Guidance to maintain an optimal aerodynamic position is currently unavailable during cycling. This study used real-time vibrotactile feedback to guide cyclists to a reference position with minimal projected frontal area as an indicator of aerodynamic drag, by optimizing torso, shoulder, head and elbow position without compromising comfort when sitting still on the bike. The difference in recapturing the aerodynamic reference position during cycling after predefined deviations from the reference position at different intensities was analysed for 14 participants between three interventions, consisting of 1) vibrotactile feedback with a margin of error of 1.5% above the calibrated reference projected frontal area, 2) vibrotactile feedback with a margin of 3%, and 3) no feedback. The reference position is significantly more accurately achieved using vibrotactile feedback compared to no feedback (p < 0.001), but there is no significant difference between the 1.5% and 3% margin (p = 0.11) in terms of relative projected frontal area during cycling compared to the calibrated reference position (1.5% margin ?0.46 ± 1.76%, 3% margin ?0.01 ± 2.01%, no feedback 2.59 ± 3.29%). The results demonstrate that vibrotactile feedback can have an added value in assisting and correcting cyclists in recapturing their aerodynamic reference position. 相似文献
16.
计算流体力学在F1赛车运动中的应用 总被引：3，自引：2，他引：1
应用计算流体力学方法优化F1赛车外形设计以改善其空气动力学特性。结果表明,应用计算流体力学方法可实现在很短的时间内完成多种设计方案的模拟计算,得到赛车外形与气动阻力系数等空气动力学特性的定量关系,还可以进行F1赛车的操纵稳定性,空气噪声,排、进气道等研究。 相似文献
17.
John Eric Goff 《Sports Engineering》2013,16(3):137-154
A review of aerodynamics research connected to sport projectiles is presented here. The review’s focus is on work conducted in the current millennium, though deference is made to some classic work still invaluable to modern research. Besides serving as a resource for seasoned scientists and engineers, this article is especially geared toward young investigators who are just beginning careers in sport science. Basic and sophisticated methods are discussed, including vacuum physics, air drag, lift, numerical approaches, trajectory analysis, wind tunnels, and computational fluid dynamics. Eighteen sports are discussed with an eye to future research. 相似文献
18.
Wind tunnel tests were carried out on seven male and seven female track cyclists and the drag measured for their current favoured racing position and for different handlebar height and separation combinations deviating from their current favoured position. The handlebars were raised or lowered using spacers on the stem, and the elbow pads were placed wider apart or closer together using the adjustment slots on the pads. The degree to which adjustments were made was dependent on the equipment used, as not all handlebars had the same amount of adjustment. The drag area was calculated from the measured drag force and the results for drag area plotted for each athlete in each position to identify the optimal handlebar position for each athlete. The results showed that the handlebar height had a greater influence on the drag area compared to handlebar separation, but that there was a high degree of variability between athletes as to the optimal handlebar position. 相似文献
19.
A review of existing mathematical models for velodrome cycling suggests that cyclists and cycling coaches could benefit from an improved simulation tool. A continuous mathematical model for cycling has been developed that includes calculated slip and steering angles and, therefore, allows for resulting variation in rolling resistance. The model focuses on aspects that are particular, but not unique, to velodrome cycling but could be used for any cycling event. Validation of the model is provided by power meter, wheel speed and timing data obtained from two different studies and eight different athletes. The model is shown to predict the lap by lap performance of six elite female athletes to an average accuracy of 0.36% and the finishing times of two elite athletes competing in a 3-km individual pursuit track cycling event to an average accuracy of 0.20%. Possible reasons for these errors are presented. The impact of speed on steering input is discussed as an example application of the model. 相似文献
20.
William M. Bertucci Simon Rogier Raoul F. Reiser II 《Journal of sports sciences》2013,31(14):1606-1613
Abstract Aerodynamic and rolling resistances are the two major resistances that affect road cyclists on level ground. Because of reduced speeds and markedly different tyre-ground interactions, rolling resistance could be more influential in mountain biking than road cycling. The aims of this study were to quantify 1) aerodynamic resistance of mountain-bike cyclists in the seated position and 2) rolling resistances of two types of mountain-bike tyre (smooth and knobby) in three field surfaces (road, sand and grass) with two pressure inflations (200 and 400 kPa). Mountain-bike cyclists have an effective frontal area (product of projected frontal area and drag coefficient) of 0.357 ± 0.023 m2, with the mean aerodynamic resistance representing 8–35% of the total resistance to cyclists' motion depending on the magnitude of the rolling resistance. The smooth tyre had 21 ± 15% less rolling resistance than the knobby tyre. Field surface and inflation pressure also affected rolling resistance. These results indicate that aerodynamic resistance influences mountain-biking performance, even with lower speeds than road cycling. Rolling resistance is increased in mountain biking by factors such as tyre type, surface condition and inflation pressure that may also alter performance. 相似文献