Multi-element wing

[Shahfiq Shahjahan]

Hi All,

I am using flightstream to run some multi-element wing simulations. I am wondering if there is limit on the distance between the two wings? With the mesh attached, flightstream simulations diverges but if increase the gap between the front and rear element, I am able to get flightstream running. The issue if we would like the gap to be converging so that it will energise the boundary layer of the rear element. By increasing the gap, that kind of defeat the purpose. I am wondering if there are any limitation on flightstream for this? 

Hope to hear from you soon and thanks for your time.

Regards,

Shahfiq

[daniel.enriquez]

Hi Shahfiq, 

Yes, there is a limit to how small the gap is. FlightStream is mainly a potential flow solver, but it has viscous corrections. In other words, for very small gaps where the flow is dominated by viscous effects and separated flow, FlightStream may not yield reliable results there. Also, you should take a look at the User Manual into Component Cross Section (CCS) format. There are built in ways for handling slots and coves. Do you know what version of FS you are using?

- Daniel

[Shahfiq Shahjahan]

Hi Daniel,

Thank you for your quick response. I am using the 2023.1 version but realised that we have 2023.2 as well. I am using CCS format to input the mesh. For now, I have two different CCS file for the front and rear element. Are you suggesting that I need to include the "Flap_cove;Name;v0;v1;u00;u01;u10;u11;cove_type;want_flap;flap_gap;slot_gap_percentage" in my front element CCS file? The idea is to run a parametric study on hinge point and deflection angle but we are a converging gaps rather than diverging as we found from our analysis before that diverging flaps are not desirable. Any suggestion? 

Shahfiq

[daniel.enriquez]

You should use the latest version as we have sent out some updates in this version. Yes, that is the parameter I mean. Play around with it to understand what it does. 

- Daniel

[daniel.enriquez]

The separation marker tells you where the boundary layer is separated. There is a separate "transition marker" that tells you where the boundary layer is laminar and turbulent. 

There really is not anything in between. Values between 0 and 1 are artifacts of contour smoothing. You can turn off contour smoothing in the Colormap settings.