flyrotary@lancaironline.net Mailing List Archive

I agree, Dave.

Putting a van or diverter near the inlet is dealing with higher velocity air as you point out and is it is also in a location that makes the angle of incident with the air flow critical. In fact, there is not any way (other than making it in-flight adjustable) that you are not going to get flow separation in some flight regime and more likely during climb, just went you need all the cooling you can get. If you must install the diverter at the entrance , then at a minimum give it a nice rounded airfoil shape to help the air make the turn.

----- Original Message -----

From: The Wilenius Family

To: Rotary motors in aircraft

Sent: Tuesday, May 29, 2007 10:31 AM

Subject: [FlyRotary] Re: Cooling Recommendations

I don't clain to know anything about this topic, but a quick search found this. These guys look like they're dealing with a bit more velocity and might be a good starting point. There is a reference to the geometry they're using. You might want to make them slightly smaller though :)

http://www.lboro.ac.uk/departments/tt/research/aerodynamics/windtunnel/vanes.html

One thing that is meantioned is that, where possible you'll want the air to expand first before going through the vanes because the energy loss is proportional to the square of the velocity. Get the velocity down before making a sharp turn ... where possible. In your case that would mean getting them as far back from the inlet as practical.

Dave

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of Ed Anderson
Sent: Monday, May 28, 2007 12:16 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Cooling Recommendations

<snip> .

Be aware that HVAC ducting is generally not dealing with air flows that they have to slow down from 160 + MPH. While I do not pretend to be HVAC knowledgeable - the environment and conditions are different - that is not to say there may not be good ideas there - just a different environment.

<snip>

Ed

----- Original Message -----

From: Dennis Haverlah

To: Rotary motors in aircraft

Sent: Monday, May 28, 2007 11:58 AM

Subject: [FlyRotary] Cooling Recommendations

Rotary Group,
Thanks for the suggestions - questions etc.

Questions and--- maybe answers

Oil pan clearance.
The oil pan is a flat bottom Renesis stock pan . In the first picture sent 5/27 it is about level with the white motor mount tube under the engine. At the front it is about 2 inches from the radiator surface. At the back it is about 8 inches above the radiator. The pan only covers some of the water rad. and none of the oil rad. I get better cooling on the water side so I don't believe it is a problem.

Duct shape.
My James cowl inlet ended about 3/4 inch inside the opening. I added foam and glass to make a smooth transition to the bottom and sides of the cowl. Air entering near the top of the inlet either turns up about 90 deg.within 2 inches of the inlet to the air filter or goes straight back to the radiator. I don't like this arrangement but don't know how much the turbulance contributes to poor cooling. My first attempt to improve the top inlet flow made cooling worse so I am looking at other areas now.

Water hose may be restrictive.
The hoses in the first 5/27 picture are oil lines to the oil cooler. An-10 to the cooler and AN-8 back to the engine.
The water coolant hoses are AN-20 not shown because they are behind and on the other side of the engine.

Turnning Vane construction.
I can easily construct a support that bolts to the bottom of the cowl. This may be able to be installed through the inlet without taking the bottom cowl off.
I have not found much information on flow turning vanes in either the K&W Chapter 12 or Hoerner's Fluid -Dynamic Drag. Probably need to look at HVAC duct design information.

Dennis H.