Mailing List flyrotary@lancaironline.net Message #66912
From: Marc de Piolenc piolenc@archivale.com <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Cooling Inlets
Date: Tue, 13 Jul 2021 10:16:12 +0800
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Wish I could dive into this, because it's something I will have to look into for the book project that I am working on, volume 2 (Cooling Systems Design) of the ducted fan book series. Right now I am hip-deep (when there's time) in ejector design.

Can't though - while dreaming of great things I have to earn my living from day to day as a free-lance technical translator, and I am getting an influx of work, with deliveries extending to the 22nd (so far).

In addition to Miley's report, you might want to get a copy of Küchemann and Weber's Aerodynamics of Propulsion, which is the basis for Miley's work. It might help you decode Miley's train of thought.

If you can get a precise definition of each parameter, preferably in terms of other parameters and variables, you will be on top of it. In researching ejectors, I was stumped for months by two NACA reports, which seemed to have two completely different values for the same parameter of the same engine. It was resolved by careful reading of the definition presented in one report, which indicated that one version covered ONLY the exhaust stroke, while the other averaged the value over the entire cycle. Oof.

Marc de Piolenc

On 12/07/2021 2:12 am,  wrote:
So Ed, you're bored?

Want to take a stab at helping me understand the below graphs and how they lead to the selection of the optimum outside/inside lip radius ratio?

I understand that Cp is pressure coefficient, pressure relative to other pressures in the vicinity.

Not clear to me if we're looking for positive or negative Cp inside the diffuser, I assume positive? (Converting airspeed into pressure)
I also assume we're looking for a profile with maximum Cp over a wide AOA range.
Why did they pick A-20 and Vi/Vo = 0.4 for figure 36d?
Aren't we shooting for a Vi/Vo of 0.2 or better? (slowing 100 mph down to 20 mph)

--
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