A flexible, lightweight structure, generally intended to retard the passage of an object through the atmosphere by materially increasing the resistive surface. Parachutes have continued to be the simplest and cheapest devices for the deceleration of payloads, people, and vehicles since their first recorded use in 1797. Comprising cloth and suspension lines, their construction is far simpler than that of aircraft. As a result, parachute construction and design is a fairly mature art. However, their very “softness” makes their aerodynamics much more complicated, so complicated in fact that modern supercomputers are not powerful enough to completely simulate both the evolution of the parachute shape and the internal and external airflows, either during inflation or during rapid flight maneuvers. Indeed, unlike aircraft, which are solid structures that deflect the air around them, parachutes not only deflect the surrounding air but also adopt shapes that are dictated by it. During inflation, such feedback is even more dominant as both shape and flows are basically unsteady (that is, do not remain constant in time). Finally, given the lack of streamlining both during and after inflation, turbulent flow rather than laminar flow controls the aerodynamics.
- 词性: noun
- 行业/领域: 科学
- 类别 普通科学
- Company: McGraw-Hill
创建者
- Francisb
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