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Knowledge of Helmholtz Resonators

Knowledge of Helmholtz Resonators

Knowledge of Helmholtz Resonators

I am interested in designing helmholtz resonators to amplify the pressure in the intake and exhaust systems of 4 cycle internal combustion engines.  Does anyone know of a good contact on this subject?

RE: Knowledge of Helmholtz Resonators

There's no web resource that accurately discusses Helmholtz resonators, as far as I know. They are inherently tuned dampers, and tend to REDUCE the pressure peaks in the manifold, so you may be on the wrong track.

You would probably be better off to look at using a half wave tuner as an amplifying device.


Greg Locock

RE: Knowledge of Helmholtz Resonators

As Greg Locock said, helmholtz resonators will reduce the amplitude.  My experience is with using them in industrial piping to suppress unwanted fluid pulsation / vibration modes.  When the resonator is resonating, it is between 90° and 180° (depending upon amount of damping) out of phase with the exciting force.  This is how it cancels or reduces the pulsation amplitude.

I believe the common method used to tune intake and exhaust systems is to vary the length to cause resonance.  The diameter must be kept within certain limits in order to both keep velocity and momentum up, while not causing excessive pressure drop.

RE: Knowledge of Helmholtz Resonators

I think you'll find that the primary damping effect in a Helmholtz tuner is due to skin friction on the high speed slug in the throat of the device, and that the phase effects are secondary. This may just apply to air/hot gas systems, not liquid.

A quarter wave tuner uses the phase effect as its primary method of attenuation, as such its bandwidth is less controllable, and generally narrower.


Greg Locock

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