Re: YASim prop discing and turboprop engine

Hello Andy!

Thanks for the answers

> 1. No, YASim doesn't model inter-surface wash and flow effects.  The
>    only airflow the surfaces see is the global one.

Would it be possible to overcome this limitation by dynamically altering a
lift coefficient separatelly for each wing, or in the worst case, using
the spoilers ?

In the aircraft I am trying to simulate (Dash8 Q400) there is a huge
difference in a lift produced by the wing with and without the propwash.


Thanks,

Oleksiy

> Oleksiy Frolov wrote:
>> 1. Wing lift change because of the propwash in twin engine airplane. 2.
>> Prop discing effect on high rpm and low torque, where propeller actually
>> produces negative thrust in close to 0 blade angle.
>
> 1. No, YASim doesn't model inter-surface wash and flow effects.  The
>    only airflow the surfaces see is the global one.
>
> 2. Yes, sort of.  YASim does model negative blade pitch (albeit in an
>    abstract coordinate space where "pitch" is a factor, not an angle)
>    Whether it does so well or not is an open question.  I don't know
>    anyone who has compared it to a real aircraft.
>
>> What simulation algorithm was used in YASim to simulate the turbine and
>> propeller physics for turboprops ?
>
> It's an energy balance model based on a nominal efficiency curve
> specified by the configuration.  This has the advantage of working
> really well in the middle of the operating range, leading to good
> thrust estimates even with minimal input data.  The disadvantage was
> mentioned above: performance at the extremes of the performance regime
> (windmilling, for another example) tends to produce funny effects.
> Some of this can probably be tuned away for a given application.
>
> Andy
>
>
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