SimScale CAE Forum

Airflow around and through an aircraft engine cowling

Hello,
I am trying to model the airflow over and through a light aircraft engine cowl. The cowl has 2 openings at the front and one at the rear. If I create an enclosure with a Velocity Input, Pressure Outlet and Slip Walls and run a simulation the airflow does not appear to go through the front openings just around the outside of the cowling. Creating an enclosure and selecting one of the openings gives me airflow through the cowl but not around it. The flow through the cowl will be effected by the flow around the cowl due to the lower pressure behind it and I want to model this.

Here is a link to the model

https://www.simscale.com/projects/kkelso/cowl_6/

Any help much appreciated
Ken Kelso

@CFD-SQUAD, could you have a look at the project from Ken and see if there’s anything going on with his geometry?

Best,

Jousef

Hey Welcome to the forum!

Taking some cutting planes of your geometry it does seem like there is flow entering the two opeinings in the front of the cowl. I assume you were expecting to see flow through the cowl by entering in the front and exiting the rear

X cutting plate at -0.12

X cutting plane at -0.03

Another useful feature is applying vectors to a cutting plane to get a sense of flow direction. So it does seem like there is flow moving through the openings.

X cutting plate at -0.12

X cutting plane at -0.03 This shows quite a bit of recirculatory flow, possibly effecting how well it exits through the rear

I would also recommend increaseing your bounding box size (enclosure size) as having one too small can effect results. Normally 10x the geometry size is good. So maybe 30m long and 5m tall/wide.

Just post again with any other questions or results

Dan

1 Like

Thank you so much Dan, I admit that as a Simscale novice I was having trouble with setting up the results so that I could visualise what I thought should be happening. I can now carry on and populate the cowling with the engine and refine the design.

CFD Simulations definitely take some getting used to but i think the updates Simscale has made over the last few years have really simplified the process. Look into particle traces (basically 3d vectors) and isovolumes (3d volume data) they are also very useful for data representation.

If you want to get into some really good verification. I highly recommend donwloading paraview and @DaleKramer’s Y+ Histogram and ORSI Programs (all free) as they are extremely useful in verifying Y+ values as well as confirming Simulation convergence.

Link to Y+/ORSI Program Thread

Dan