German Car Zone - View Single Post - Aerodynamics Guide

Bruce · **Re: Aerodynamics Guide - Autmobilismo -** 11-06-2006, 12:07 PM

"The studies more are left over to you obviously have been made in aeronautical field. From them many solutions consolidated in the automotive field (like note come already the ailerons), and them the planners watch constantly in try of inspiration. Recently, Mitsubishi has introduced for before the time on an car - seppur particular like the Lancer Evo IX - of the vortex generators, dispositi to you employs to you on the airplane in order to improve of the maintenance in stall position, during the takeoff and the landing. As it has been looked at, the viscosity of the air the door to try to join to the superficial ones on which it slides: in the zone of the rear window the vein moves towards the bottom, it slows down, and it increases its pressure. A reversal of the motion is had then: the air stretches to return (whirpool behind). The “fins” of Evo IX do not make that to generate vortices in opposite sense to those of whirpool, that they stretch therefore to ridurli. Practically, they capture energy from the advanced regions and the convogliano where the flow has lost energy, riaccelerando the vein: that delays the separation, moving the point correspondent towards the posterior part of the vehicle. On the whole the depression that shape beyond the tail is reduced, and with it the forces of aerodynamic friction that “refrain” the car. The pressure to the separation point governs in fact the regimen of pressures of all the turbulent part: a benefit in this point ripercuote therefore on the entire turbulent flow. The numerical synthesis of these phenomena is a reduction of the value of Cx, that it turns out beneficial until (and if) remains greater of the which had worsening of the Cx to the increase of turbulence induced just from the generators. The things are not insomma therefore simple and are necessary to do good the accounts in order to find the shape, position and optimal dimension. Also in the event optimal, the effect is however rather modest. The Mitsubishi investigators have obtained one reduction of the Cx of 0,006 (approximately 2%). It seems but that this idea is obtaining a sure one succeeding on the trucks Americans, where it comes used in order to create a “aerodynamic bridge” in the zone between engine and towing and in order to limit the posterior turbulence. In this case the benefit could be the little marked one, also because these vehicles stretch to maintain the same cruise speed for long features. But it must keep in mind who every aerodynamic appendix, to beyond the considerations of aesthetic opportunity, has an impact on the emergency and the praticità of use (visibility, requirement lawyers, etc): for which if the advantage that it confers is not determining, difficultly it comes adopted in the mass production.

One of these is senz' other the prototype Mercedes Bionic Car introduced in 2005. A plan that is inspired declared to the animal world is in the external shape that in the development of the chassis, obtained with a model that it reproduces the increase of boneses. The German technicians, frustrate to you from the difficulty to conciliate the demand for space and the shape tendentially “to scato it” of the succeeding monovolume of, have begun to study the “fish scato it” (boxfish), a tropical fish of practically cubical aspect but from the above suspicion efficiency hydrodynamics. With they great surprise, in wind tunnel, to Stoccarda a model of the fish showed one incredible Cx of 0,06: nearest the record of the water drop! Before maquette of the car inspired to those shapes it caught up 0,095, a value never obtained from no not even prototipale car (Ford Probe V of 1986, practically a torpedo on wheels, had “only” 0,137). The definitive version of the prototype, with many which had worsenings to homologation and style issues, still boasts excellent 0,19. Bionic Car has demonstrated definitively that it is possible to obtain substantial improvements of the Cx without to resort to the usual shape from Space Shuttle, to pact to place one good penetration as bench mark from the beginning of the plan. Bionic Car moreover takes advantage of various technologies already available on the cars odierne, between which the shunters of flow whom they remove the air from the zones to greater turbulence, like that near the wheels. The principle, various (and in a sure opposite sense) from that one of the vortex generators, already is taken advantage of from many Houses, on the wake (is the case to say it) of Bmw and Mercedes. They work little like the vortex generators: they generate around the ball a thin layer of turbulence, than having greater energy it joins with more vigor to the surface. The separation of the vein happens therefore later, and gives to place to one smaller wake: approximately the half, that it halves also the resistance coefficient. There are then also positive effects you on the carrying capacity, than but the players interest more than golf that not the motorists. The motorists will ask themselves instead as never this effect never has not been taken advantage of. The reason is that unfortunately the dents work less well on the automobiles: perhaps they would help in the event of the New Beetle, but in general terms it does not convene to go to the search of one hailstorm in the hope to save on the successes to you refueling. The Class and, in the models of tip to 6 cylinders, as an example adopts a system of regulation of the air inlet one in the front bumper composed from 16 lamelle in plastic elettroattuate. The edge computer regulated the opening of these lamelle to second of the temperature of the motor and the speed of march, and in the event that air flow is not necessary closes the opening completely. In this way one is obtained also reduction of Cx the par to approximately 3%. Analogous, Lexus LS introduces miniums-spoiler (wide 20 cm and high 3) specific ones for ciascuna wheel. From these short notes he is already obvious like the study of the aerodynamic flows has made in a short time steps from giant, allowing as an example to the Bmw endowed of flame surfaces, like the Z4, to dull optimal values of aerodynamic resistance. For our fortune, the future is insomma less round than how much it was believed: we can today sorridere of the escaped danger watching to the pioneering efforts of Chestnut and of its epigoni."