Arnt Karlsen wrote: > > > Andy Ross wrote > > > > > > > > Drew wrote: > > > > IMHO, it's best to use interpolation tables rather than equations > > > > if you're trying to curve fit empirical data. > > > > > > Not in this context. The data here isn't being used to model a > > > specific engine, but to provide sane parameters for all > > > (super/turbochared) engines. The performance and code size > > > advantages of an equation here are significant. > > > > > > > At the moment we are looking at gear driven centrifugal compressors. > > Although I haven't researched it in any detail, the output of > > turbo-driven centrifugal compressors do not have a direct relationship > > with rpm (turbo lag), and the situation is complicated by the > > wastegate which operates on the turbo rather than the compressor. I > > suspect that this is another black art! Gear driven is easy in > > comparison. When someone comes up with a turbo we may have to have > > separate models. > > ..if your supercharger code takes shaft input (shaft speed, torque or > power), then it can be re-used in the turbocharger's compressor code.
It doesn't because a gear driven compressor has a fixed relationship to engine rpm, and I deal with 2 speed superchargers separately, but you are right: a centrifugal compressor neither knows nor cares if it is gear- or turbo-driven. > ..the turbocharger's compressor or turbo-compound engine's crankshaft > then only needs a turbine derivering shaft outnput (shaft speed, torque > or power) to the compressor or gear box. > Now, if we knew what the turbo rpm was for a given engine rpm, and I think we need throttle opening ... any guidance welcome. Otherwise ... it's going to have to be magic mushrooms. Regards, Vivian _______________________________________________ Flightgear-devel mailing list [email protected] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
