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经典图书
In this article we will try to determine the value of a lift force as a function of a forward lean angle (FLA) of Ski jumper. To find this characteristic, we tested four different body position. The body position in our studies are shown in the figures below.
Definition of case studyIn the first step we will try to estimate the real velocity of ski jumper which depends on the forward lean angle. The most important is to find the drag force for each case. To do this, we define two goals: drag force and lift force on surface of a ski jumper’s body.
For all cases, we assume that horizontal velocity component of a Ski jumper is equal to 100 km/h.
After doing the necessary calculations, we know the value of Drag force for velocity of 100 km/h for each FLA. By including decreased velocity and increasing Drag force, the following equation will determine real velocity for Ski jumper.
ResultsBelow we can observe the distribution of aerodynamic drag coefficient as a function of FLA
In the first case, the biggest aerodynamic resistance appears on surface of head (fig. 2a). This resistance increases together with the increase of FLA and moves towards chest and shoulders (fig. 2b), forearms and abdomen (fig. 2c), to finally cover all front area of a ski jumper’s body (fig. 2d).Figures 3. show the streamlines that are passing the ski jumper. For a low value of forward lean angle, we can observe a laminar flow. For a high value of forward lean angle, the airflow is separating
Based on the simulation results, we can draw a graph that represents the lift force as a function of forward lean angle
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发表于 2017-4-30 10:54:48
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