Trying to modify my grill block to be more aerodynamic.

[freebeard]

This is where that comes from. There exists a version that wasn't photographed off a monitor.

[He-man]

Originally Posted by freebeard

This is where that comes from. There exists a version that wasn't photographed off a monitor.

That is really helpful, thanks! Ill try to get it as airtight as possible

[aerohead]

Originally Posted by He-man

So from my reading I just did the stagnation point will be in the middle of the vehicle probably centered in the grill?

By definition,at the forward stagnation point,the air actually comes to rest.It's just impacting the body,with full dynamic pressure.
If you mixed carbon black (lamp black) and kerosene and dribbled it on the nose of the car,then immediately drove fast,the stagnation point(s) (forward) would be revealed by any dots which failed to smear off in some direction.
And this would be the best place to site the cooling inlet.

[aerohead]

Originally Posted by He-man

Also, if it were to be centered would type 1 or type two be better. Would an abrupt entrance be best or would a sloped entrance be best for an inlet? I seen both on the vehicles that are posted. Thanks!

The inlet opening should be perpendicular to the flow all around ingesting the blue pressure spike

And the inlet itself should not have squared edges of the flow will be choked off with what is referred to as a vena-contracta

The inlet and airtight ductwork should be like the venturi inside a carburetor

[maschinenbauer]

Hi sort of off topic and maybe covered elsewhere but I saw your pressure map a couple posts up and I am just curious if running your outside vent (fresh air) fan in the car, assuming the air scavenges from beneath the hood at the wipers, would pull enough air from the high pressure zone at the bottom front of the windshield to improve drag more than energy consumed by running the fan?

Thanks!

[freebeard]

Probably not. Tuft testing would tell if there is a positive effect, but won't quantify it.

My guess is that attaching a leaf blower to the vent might. The blue area reaches halfway up the windshield and out onto the hood. There's a lot of air moving through the high pressure zone with maybe a little bale of rotating air right at the base. The air an inch or so off the surface is being flattened by the onrushing volume of air.

[aerohead]

Originally Posted by maschinenbauer

Hi sort of off topic and maybe covered elsewhere but I saw your pressure map a couple posts up and I am just curious if running your outside vent (fresh air) fan in the car, assuming the air scavenges from beneath the hood at the wipers, would pull enough air from the high pressure zone at the bottom front of the windshield to improve drag more than energy consumed by running the fan?

Thanks!

The entire front of the car,right up to the windshield header,over the roof,and door sides (depending on the vehicle) is attacking the air and the air is held against the body up to the region where the body reaches it's maximum cross-section.Flow attachment here isn't really an issue.
The horsepower available from the ventilation fan wouldn't even register in comparison to the power of the airstream.Also,you'd want as much air moving outside the car as possible,as internally,it's a torture chamber.
A 'blown',or 'suctioned' slot would do more good at the back of the car,where it could energize an otherwise feeble boundary layer which is at risk of triggering separation

[freebeard]

A 'blown',or 'suctioned' slot would do more good at the back of the car,where it could energize an otherwise feeble boundary layer which is at risk of triggering separation

A case on point: 1500 cubic feet per minute of engine cooling air (not the exhaust) into a ring-shaped slot at the rear of a boat tail. This might have some effect.



The one on the left. This is called a Coanda nozzle.

(aerohead — I'm going to take some Aluma-panel upriver after it thaws and fashion a boat tail for the '58 Baja.)