How does a spoiler in a car work ?
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Spoilers are for turbulence.
Wings are for downforce.
Dont get them mixed up.
The spoiler on a road car is designed to reduce turbulence. The less turbulence on a car the less drag. Lower drag means lower fuel consumption.
They have nothing to do with ‘pushing the car down’
A spoiler IN a car doesn’t work. It needs to be on the outside. See other posts for how spoilers work ON a car.
A spoiler is a device that spoils the flow of air. So if something would create turbulence and therefore drag you can place a spoiler in place to reduce the turbulence. Spoilers can work in different ways. One area where turbulence would normally occur is on the back of the car. In slow speeds the air will pass over your car and down behind it. However if you increase your speed the air will start separating from the surface and go straight back. This creates a zone of low pressure air behind the car sucking it backwards. So a carefully designed spoiler in this area will usually help reduce the drag on the car. It can for example push the air down behind the car or create turbulence that makes it easier for the air to go around the corners of the car. Note that you should also not confuse a spoiler with a wing. Wings are intended to create down force that helps the car around high speed corners and will actually increase the drag on the car as opposed to spoilers which will decrease the drag.
I’ll start by clarifying that there’s a difference between a wing and a spoiler, and they don’t do the same thing. The first two responses got it wrong, but it’s something that is commonly misunderstood, so they’re not alone.
Wings are used to push the car into the ground, which generates more friction on the tires, increasing grip/traction. This is “aerodynamic downforce.” Essentially, an airplane wing turned upside down. Wings generally stand off the bodywork of the car.
Spoilers work to disrupt air flowing close the car in ways that aren’t efficient or desirable, including turbulent air near the car that causes drag, reduces overall downforce, and/or too much noise. One key location for spoilers is the rear, where the spoiler works to free the air swirling around the rear window, and at the back of the the trunk that would otherwise pull backward on the car (like eddies in a river).
Another way to think of it is that, by messing-up the air that’s close to the car, the air flows around the car are much smoother (“laminar”), so the car performs better. Spoilers are all over the car, too – in the front air dam, on the underside of side mirrors, etc. Spoilers can generate their own downforce too, but its often secondary to the job of disrupting other bad air. Spoilers are generally closer to the bodywork than wings, and are often molded into the trunk lid and fenders.
Does that answer your question, or are you asking also about how wings and spoilers actually use air to create negative lift (wings) or reduce/disrupt/increase/redirect air and air pressures?
[edit] I thought of another, more ELI5 way to describe what a spoiler does: think of a river flowing over a hole. The water will want to fall into the hole, but since there’s water in the hole already, it’ll push some of that hole water out and up in a rough way, mixing with the smooth water and swirling around (turbulence), causing the water flowing around it to slow down. But if you were to add a flat stick (spoiler) before the hole, it’ll kick water up and away from the hole, smoothly (laminar), so it passes over the hole faster (with less drag). A spoiler works in a similar way on a car.
You know when you’re driving down the highway on a nice day and you stick your hand out the window and feel the air moving around it? You tilt it up and the force of the wind almost lifts your arm for you. You tilt it down and it pushes your hand and arm towards the ground. The spoiler works the same way. It has that downward tilt, which pushes the back of the car towards the ground and gives it extra traction.
Faster you go, the more air blows onto it. The spoiler is angled I’m such a way that the air blowing over it pushes it down into the ground, creating what’s called downforce. That allows you to have more grip in the tires as if the car was heavier than it actually is.
So when you go faster the more air there is. Some of that air goes over the car. The spoiler uses that air (speed) to push down on the car to create more traction (drag) for the tires and also keeps the car from going aiborne (Lift)
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