Rijke Type Big Oscillation Standing Wave Pipe Acoustic Characteristics And Noise Reduction

The Rijke pipe is an important heat acoustic mechanism. It can use the heat energy which is low quality energy to drive the mechanism. The working fluid didn't damage the circumstance. The Rijke pipe's natural life is very long and it can improve heat transfer and burning efficiency. It also can reduce NOx .The purpose of this thesis are analyzing the Rijke pipe's self-excited mechanism and researching nozzle effect to reduce the noise of Rijke pipe to breach the engineering constrict.The thesis gives a new hypothesis about the relationship between the airs around heat source's unstable heat release and oscillation pressure, oscillation velocity. There are two force oscillations. One is appending heat sources decided by time the other is append manual temperature grads. This thesis doesn't use these forced triggering mechanisms but Complete the Rijke numerical simulation rely on the parameter without time part; it is agreement with the fact which Rijke is a self-excited mechanism. The thesis simulates Rijke and the space connects to it to replace tradition methods which only research Rijke itself. And analysis physics phenomenon. Give the reasonable explain. The thesis uses experiment to prove the simulation. The numerical experiment pay more attention to Rijke pipe's nozzle effect for reduce the noise. At last the thesis sum up noise reduction methods for Rijke pipe which noise is low frequency big oscillation value and loud noise. In these method it contain new method called 1/4 wavelength pipe.This thesis reviews existing research include analytical method numerical simulation and experiment. It also gives a new hypothesis and offers the explanation of the Rijke pipe's self-excited mechanism. The conclusion is agreement with the experiment. All these work is the base of deeper research of the Rijke pipe.