COnstant gas velocity

Question

COnstant gas velocity

robotengineer (Nuclear)

(OP)

2 Mar 00 08:38

THanks in advance,
Is any work being done on technology to maintain a constant velocity of charge as air/fuel pases valves on an intake charge. The advantages on combustion chamber design are well known, and attempts to minimize the turndown ratio along the whole rpm range have been feeble thus far.
Is anyone pursuing constant velocity charge?
Regards

VCam (Mechanical) · Answer 1 · 2000-03-02 13:30:54

This can be accomplished by throttling the engine with the intake valves. It has the benefit you mentioned - that of improved charge tumble and reduced cylinder wall wetting; both of which improve partial throttle burn efficiency and reduce emissions. It also has the benefit of reducing butterfly valve pumping losses. A bunch of people aare working on variable lift valves (including myself). Honda guys did an SAE paper on a hydraulic variable valve train (SAE #930820) that you might find inetesting. Good luck.

robotengineer (Nuclear) · Answer 2 · 2000-03-02 16:14:46

VCAm,
THanks. I'll review that SAE paper. I guess I don't understand. When the gas flow is decelerated during the exhaust cycle, it has to be re accelerated again..in addition, the cross section of the intake runner is too big at low flow (resulting in low velocity) or too small at high flow (resulting in DP loss).
I know the Japanese have the two runners to select the appropriate cross section (thus approximating constant velocity)but this seems a bit awkward.
Wouldn't a

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