VSPAERO-Calculation principle of propeller and disk

[Haoliang Yu]

Hi,

I have learn some demos on Youtube, but I want to know the areodynamic principle of calculation, especially with propeller and disk. So are there any articles or books show the priniclple for calculation in VSPAERO?

Many thanks

Knight

[Rob McDonald]

The actuator disk method is one developed by John Conway.  There are a number of papers that he published on the subject.  Most of the work was published in the Canadian Aeronautics and Space Journal from about 1995-2000. 

The rotating blade method has no 'special' formulation beyond the unsteady time-accurate formulation for the rest of VSPAERO.  The rotating blades produce an unsteady flowfield that is solved like any other.

Rob

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[Haoliang Yu]

I got it.

Thanks!

[Haoliang Yu]

Hi,

I have read Convey's paper which you mentioned.

But when I see the youtube video, I find that there is Johnson's actuator disk model for tangential velocity.

The video can just show part of the powerpoint, I want to know more details.

I try to find papers by the keywords. But I couldn't find it.

So what is the title of this paper by Johnson?

I want to read it.

Many thanks,

Knight

[Brandon Litherland]

Check Johnson's "Helicopter Theory" sections 2-1 to 2-3 around page 28 to 45.  A lot of this comes from the rotor profile drag corrections and you won't find the formulas all next to each other.  They are spread out a bit in the actuator disk and momentum theory sections.  Also know that the CT and CP values in OpenVSP are based on the propeller definitions using rho, n, and D (density, rev/sec, diameter) rather than the rotor definitions which are shown in the slide.

[Haoliang Yu]

Hi,

I have know what you have told me. Thank you very much.

And I run some cases by vspaero, I have some questions to ask.

I am running a DEP config like this, and use the disk mode.

But today I have see this paper"Evaluation of VSPAERO Analysis Capabilities for Conceptual Design of Aircraft with Propeller-Blown Wings"

It tells that to set far field distance=50, but I do  not set this para, I don't make sure if it is necessary for disk mode, because I have run many cases and plot some results.

If this para is necessary to set and make a big difference to result, please tell me.  I will run all cases again from beginning.

I was worried about that.

I wish that I don't need to add this para set, which will save a lot of time.

Many thanks,

Knight

[Brandon Litherland]

The Far Field Distance won't have much (if any) effect on the VLM-Disk results.  It was more to capture the behavior of the visualized wakes in Viewer downstream to compare to the other tools.

[Haoliang Yu]

Hi,

I have seen these two parameters.

I really don't understand these two parameters.

So when should we set it "on" ?

When do something for Hover Analysis?

But I find that in this paper for a tractor propeller analysis, it also sets these two parameters "on" and input some values.

If I do some anlysis for DEP configurations, need I input these parameters?

Many thanks

Knight

[Brandon Litherland]

The reference mach and velocity are generally for hover cases where Vinf = 0.  You can activate the options if there is a large difference between the Vinf and Vref but in most cases you won't need to.  If you are running a time accurate unsteady case with rotating blades, you may find that including Vref will help the convergence and accuracy of the rotor but not always.  Test it out and see if your case needs the option to capture the effects that you are interested in.  If it works without Vref, then leave it off.