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2007
Conference Paper
Titel
Numerical simulation of the flow in the flue organ pipe
Abstract
Sound generated in a flue organ pipe is susceptible to the voicing adjustment. A small change in the configurations of the flue, lower and upper labiums, etc. often results in a great change in the sound. This research aims to clarify the effect of the voicing adjustment on the physical properties of the air jet emerging from the flue and thus on the output sound. Two specific adjustments are considered here: the height of the lower lip relative to the languid and the inner geometry of the foothole. The numerical simulation of the jet emerging from the flue of a modelled wooden organ pipe was first carried out. By changing the height of the lower lip, the direction and the velocity profile of the jet were calculated. The air flow in the pipe foot of a modelled metal pipe was also simulated. It was found that two different states of the flow exist depending on the foothole inner geometry: the circulation of the flow in one state has the opposite direction to that in the other. These observations were then used for estimating the output sound. To this end, sound was synthesized using a physical model that is a set of differential equations with delayed feedback describing the sound generation in the flue organ pipe. A sound demonstration illustrating the voicing effects on the sound will be presented.