Aerodynamic drag reduction in winter sports: The quest for “free speed”

2020 ◽  
pp. 175433712092109
Author(s):  
Len Brownlie
Keyword(s):  
Wind Tunnel ◽  
Drag Reduction ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Ice Hockey ◽  
Future Research ◽  
Alpine Skiing ◽  
Winter Sports ◽  
Speed Skating ◽  
Cross Country

The Winter Olympics are a highly competitive sporting environment where subtle improvements in performance can impact the finishing order in many events. Aerodynamic drag is known to be a significant resistive force to human movement in high-speed sports, such as alpine skiing, speed skating and bobsleigh. Aerodynamic drag also represents an important determinant of performance in sports such as ice hockey, snowboard cross and cross-country skiing. From 2000 to 2018, a series of wind tunnel–based research projects were conducted to provide aerodynamically optimized apparel, equipment and wind tunnel simulation training to elite Canadian and American winter sports athletes involved in bobsleigh, skeleton, luge, ice hockey, speed skating, cross-country, alpine and para-alpine skiing, biathlon, ski-cross and snowboard cross. This article reviews the role of aerodynamic drag in winter sports, considers fundamental principles of air flow around bluff bodies and methods of drag reduction in ice and snow sports, while providing experimental results from an extensive database of wind tunnel investigations. Deficits in the literature suggest productive areas for future research to improve athletic performance in these sports.

Investigation on Aerodynamic Drag Reduction of Commercial Truck Based on External Styling of Cab

2013 ◽  
Vol 307 ◽  
pp. 186-191 ◽  
Author(s):  
Peng Guo ◽  
Xing Jun Hu ◽  
Yun Yun Zhu ◽  
Qiang Fu ◽  
Xin Yu Wang ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Wind Tunnel ◽  
Drag Reduction ◽  
Energy Saving ◽  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Impact Mechanism ◽  
Aerodynamic Drag Reduction ◽  
The Impact

Aerodynamic drag reduction of commercial truck at high speed is one of the important ways to reduce its energy consumption. CFD simulation and wind tunnel tests are performed on a kind of commercial truck, to study the influence of the cab shape and different kinds of guide cowls on aerodynamic drag, and the impact mechanism was also analyzed. It shows that the cab shape will make great contributions to the aerodynamic drag while the truck travelling, and through improving the shape of cab, guiding the air flow passed, it can effectively reduce the aerodynamic drag and achieve energy saving.

Experimental Studies on Aerodynamic Characteristics of Pantograph System According to the Pantograph Cover Configurations for High Speed Train

2011 ◽  
Author(s):  
Yeongbin Lee ◽  
Minho Kwak ◽  
Kyu Hong Kim ◽  
Dong-Ho Lee
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Aerodynamic Force ◽  
Experimental Studies ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Experimental Models ◽  
High Speed Train ◽  
Drag And Lift

In this study, the aerodynamic characteristics of pantograph system according to the pantograph cover configurations for high speed train were investigated by wind tunnel test. Wind tunnel tests were conducted in the velocity range of 20∼70m/s with scaled experimental pantograph models. The experimental models were 1/4 scaled simplified pantograph system which consists of a double upper arm and a single lower arm with a square cylinder shaped panhead. The experimental model of the pantograph cover is also 1/4 scaled and were made as 4 different configurations. It is laid on the ground plate which modeled on the real roof shape of the Korean high speed train. Using a load cell, the aerodynamic force such as a lift and a drag which were acting on pantograph system were measured and the aerodynamic effects according to the various configurations of pantograph covers were investigated. In addition, the total pressure distributions of the wake regions behind the panhead of the pantograph system were measured to investigate the variations of flow pattern. From the experimental test results, we checked that the flow patterns and the aerodynamic characteristics around the pantograph systems are varied as the pantograph cover configurations. In addition, it is also found that pantograph cover induced to decrease the aerodynamic drag and lift forces. Finally, we proposed the aerodynamic improvement of pantograph cover and pantograph system for high speed train.

Experimental Model of the Aerodynamic Drag Coefficient in Alpine Skiing

2004 ◽  
Vol 20 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Caroline Barelle ◽  
Anne Ruby ◽  
Michel Tavernier
Keyword(s):  
Wind Tunnel ◽  
Drag Coefficient ◽  
Experimental Model ◽  
Aerodynamic Drag ◽  
Aerodynamic Force ◽  
Alpine Skiing ◽  
Aerodynamic Properties ◽  
Speed Performance ◽  
Aerodynamic Drag Coefficient ◽  
The Impact

Aerodynamic properties are one of the factors that determine speed performance in Alpine skiing. Many studies have examined the consequences of this factor in downhill skiing, and the impact of postural modifications on speed is now well established. To date, only wind tunnel tests have enabled one to measure aerodynamic drag values (a major component of the aerodynamic force in Alpine skiing). Yet such tests are incompatible with the constraints of a regular and accurate follow-up of training programs. The present study proposes an experimental model that permits one to determine a skier's aerodynamic drag coefficient (SCx) based on posture. Experimental SCx measurements made in a wind tunnel are matched with the skier's postural parameters. The accuracy of the model was determined by comparing calculated drag values with measurements observed in a wind tunnel for different postures. For postures corresponding to an optimal aerodynamic penetration (speed position), the uncertainty was 13%. Although this model does not permit an accurate comparison between two skiers, it does satisfactorily account for variations observed in the aerodynamic drag of the same skier in different postures. During Alpine ski training sessions and races, this model may help coaches assess the gain or loss in time induced by modifications in aerodynamic drag corresponding to different postures. It may also be used in other sports to help determine whether the aerodynamic force has a significant impact on performance.

scholarly journals The Impact of Skinsuit Zigzag Tape Turbulators on Speed Skating Performance

2021 ◽  
Vol 11 (3) ◽  
pp. 988
Author(s):  
Nando Timmer ◽  
Leo Veldhuis
Keyword(s):  
Wind Tunnel ◽  
Olympic Games ◽  
Aerodynamic Drag ◽  
World Record ◽  
Speed Skating ◽  
Record Data ◽  
Winter Olympic Games ◽  
The Impact

At the 1998 Nagano Winter Olympic Games, zigzag tape was introduced on the race suit lower legs and cap of speed skaters. Application of these zigzag devices on live skaters and cylinders in the wind tunnel showed large improvements in the aerodynamic drag. These wind-tunnel results were unfortunately not widely published, and the impact of the zigzag strips in a real skating environment was never established. This paper aims to show the background of the application of the zigzag tape and to establish the impact it may have had on speed-skating performance. From comparisons of 5000 m races just before, during and just after the Nagano Olympics and an analysis of historic world record data of the 1500 m men’s speed skating, the impact of the zigzag tape turbulators on average lap times on 1500 and 5000 m races is calculated to be about 0.5 s.

Gliding flight: drag and torque of a hawk and a falcon with straight and turned heads, and a lower value for the parasite drag coefficient

2000 ◽  
Vol 203 (24) ◽  
pp. 3733-3744 ◽  
Author(s):  
V.A. Tucker
Keyword(s):  
Wind Tunnel ◽  
Mathematical Models ◽  
Drag Coefficient ◽  
High Speed ◽  
Aerodynamic Drag ◽  
The Body ◽  
Head Turning ◽  
Drag Coefficients ◽  
Spiral Path ◽  
Gliding Flight

Raptors - falcons, hawks and eagles in this study - such as peregrine falcons (Falco peregrinus) that attack distant prey from high-speed dives face a paradox. Anatomical and behavioral measurements show that raptors of many species must turn their heads approximately 40 degrees to one side to see the prey straight ahead with maximum visual acuity, yet turning the head would presumably slow their diving speed by increasing aerodynamic drag. This paper investigates the aerodynamic drag part of this paradox by measuring the drag and torque on wingless model bodies of a peregrine falcon and a red-tailed hawk (Buteo jamaicensis) with straight and turned heads in a wind tunnel at a speed of 11.7 m s(−)(1). With a turned head, drag increased more than 50 %, and torque developed that tended to yaw the model towards the direction in which the head pointed. Mathematical models for the drag required to prevent yawing showed that the total drag could plausibly more than double with head-turning. Thus, the presumption about increased drag in the paradox is correct. The relationships between drag, head angle and torque developed here are prerequisites to the explanation of how a raptor could avoid the paradox by holding its head straight and flying along a spiral path that keeps its line of sight for maximum acuity pointed sideways at the prey. Although the spiral path to the prey is longer than the straight path, the raptor's higher speed can theoretically compensate for the difference in distances; and wild peregrines do indeed approach prey by flying along curved paths that resemble spirals. In addition to providing data that explain the paradox, this paper reports the lowest drag coefficients yet measured for raptor bodies (0.11 for the peregrine and 0.12 for the red-tailed hawk) when the body models with straight heads were set to pitch and yaw angles for minimum drag. These values are markedly lower than value of the parasite drag coefficient (C(D,par)) of 0.18 previously used for calculating the gliding performance of a peregrine. The accuracy with which drag coefficients measured on wingless bird bodies in a wind tunnel represent the C(D,par) of a living bird is unknown. Another method for determining C(D,par) selects values that improve the fit between speeds predicted by mathematical models and those observed in living birds. This method yields lower values for C(D,par) (0.05-0.07) than wind tunnel measurements, and the present study suggests a value of 0.1 for raptors as a compromise.

Wind Tunnel Test for Drag Reduction of Airfoil Bionic Soft Surface

2013 ◽  
Vol 461 ◽  
pp. 767-778 ◽  
Author(s):  
Xue Peng Zhang ◽  
Yong Hua Wang ◽  
Lu Quan Ren
Keyword(s):  
Wind Tunnel ◽  
Drag Reduction ◽  
Silicone Rubber ◽  
Aerodynamic Drag ◽  
Wind Tunnel Test ◽  
Aquatic Organisms ◽  
Soft Surface ◽  
Rigid Surfaces ◽  
Different Thickness

The soft surface of birds and aquatic organisms in the nature can effectively reduce the drag. Inspired by the fact,in this paper, an attempt is made to stick silicone rubber soft surface on the surfaces of NACA 4412 and NACA 6409 airfoils. The drags, lifts and lift-drag ratios of airfoils with soft and rigid surfaces in 5 different thickness were compared through wind tunnel test under the condition of α = 0 °. The results show that most of the bionic soft surfaces play the role of reducing the aerodynamic drag, and also increasing the lift at the same time, in which the soft surface of 0.6mm had the most significant effect of drag reduction and lift increasing.

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