inertia mass
inertia mass
(OP)
To settle a debate of inertia mass, I would like some input.
The debate is that there is so much emphasis on light weight reciprocating and rotating mass for throttle respond and/or racing etc. that in application like constant RPM and constant load, the weight of these masses has minimal effect on power output. I think it’s understood about the rotating mass not making any real difference; the real question is about the reciprocating mass. And since it’s at a constant RPM you don’t have to accelerate it, the assumption is that the energy to accelerate the mass from TDC is returned at BDC regardless of the mass. Your opinions are appreciated.
al1
The debate is that there is so much emphasis on light weight reciprocating and rotating mass for throttle respond and/or racing etc. that in application like constant RPM and constant load, the weight of these masses has minimal effect on power output. I think it’s understood about the rotating mass not making any real difference; the real question is about the reciprocating mass. And since it’s at a constant RPM you don’t have to accelerate it, the assumption is that the energy to accelerate the mass from TDC is returned at BDC regardless of the mass. Your opinions are appreciated.
al1





RE: inertia mass
There are other reasons to keep reciprocating mass low.
RE: inertia mass
Yes that was the question, but could you give me the other reasons to keep the mass low.
al1
RE: inertia mass
RE: inertia mass
The only thing not making any real difference is the idea of constant RPM. There is no such thing for an internal cumbustion engine. The basic rules still apply.
RE: inertia mass
RE: inertia mass
Did you read all the posts in the thread. ivymike has already answered the question.
Power is measured at steady RPM and as previously indicated lowering rotating mass will make no difference and reducing reciprocating mass will make little if any difference.
Apparent power difference can be substantial in an accelerating engine as some power is lost in accelerating the moving engine parts.
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RE: inertia mass
RE: inertia mass
I don't know how to calculate or measure this parameter accurately, may anybody give me some advises?
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-Fu
RE: inertia mass
RE: inertia mass
Regards
-Fu
RE: inertia mass
CAD models can be used for many components to determine PMOI. In the absence of CAD models, you can measure PMOI using a torsional pendulum (for the rotating comps anyway).
RE: inertia mass
Thank you very much for your help. I am working on it.
Regards
-Fu