Simulation Of Microwave Field For Resonance Cavity Of Air Depurant In Finite Element Method

In later years, many new technology and new method appear incessantly. One good technology should be used in many similar but different domains. The intention of this paper is to accomplish process which is from practice to theoretics and return to practice. One successful transplant of technology means that the goal can be accomplished that the same technology can be used in the different investigate item.It is a new technology, microwave is applied for the regeneration of the particle trap on diesel engine. for many years'investigate, it has been ameliorated. But the most of study are stop in the phase of the experimentation. They didn't find a integrated theoretices. That stop the technology from being used in other domains. In this paper, we want do something in this question.By reason of the length of this paper, we don't introduce the microwave calefaction theoretices and the finite element method which we had been familiar with. We only need to know that, because the microwave calefaction theoretices, the temperature T and electric field intensity E have the mapping connection. In some qualification, if we know the electric field intensity, we will find the temperature. In the same time, we can prove that the finite element method is a appropriate method which can compute the electric field intensity in the cavity. On the other hand, we work on the experimentation, to analyse it's the base on the theoretices.The particulate filter is cordierite wall flows honeycomb ceramics carrier, which was made in Corning Environmental Technologies US, Wall thickness is 0.2-0.5 mm Each square inch 100 Hole, aperture of the cell wall is 12-15 micron 285mm long 305mm diameter. The particulate trap external dimension is 420 mm long The diameter is 300 mm. microwave is shielded with the wire netting at the inlet and outlet in the particulate trap, the entire cordierite filter surface all have contained the catalytic activity oxide compound which obtained by heat treatment method, the microwave source is a magnetron, power is 900w, the working voltage is 220V, and the ideal operating frequency of magnetron is 2450MHz。 First we use electromagnetic field theory to calculate the microwave vibration pattern in the resonant cavity. General regarding the complex resonant cavity in the microwave pattern computation, the complex resonant cavity is predigested to a simple one, therefore we predigest above resonant cavity to a cylinder cavity. We had considered the filter material is transparent to the microwave, so neglected the influence of the filter to the microwave field. There may be TE (H) Vibration patterns and TM (E) Vibration patterns in the cylindrical resonant cavity.The general expression of resonant wave lengthλ₀ is:Amongλc is cut-off wavelength, L is length of the resonant cavity, P is the sign of the vibrate pattern.Regarding TE Vibration pattern in cylindrical resonant cavity :Among is the N-th root of the derivative of M dimensions Bessel function, is the end surface circle radius of the column cavity, (M=0,1,2…; N=1,2…; P=1,2…)The resonant wavelength obtained with substitution expression of resonant wave length is: For TM Vibration pattern in cylindrical resonant cavity:Among xm nis N-th root of the M dimensions Bessel function , is the end surface circle radius column cavity,(m=0,1,2…; N=1,2…; P=0,1,2…) the resonant wavelength obtained with Substitution expression of resonant wave length is:According to resonant wavelength formulas in TE Vibration pattern and TM Vibration pattern, we can obtain the resonance frequency formulas respectively is:The frequency of microwave source has some fluctuation in work time. When the resonance frequency of some kind of microwave vibration pattern in the scope of microwave source frequency fluctuation, it indicated that there is this kind of microwave vibration pattern in the microwave cavity. the scope of the microwave source frequency in this experimental is [ 2.42×109Hz,2.48×109Hz ],Radius a is 15cm, length of the cavity L is 42cm,combined with the Bessel function root and its derivative's root, we may obtain m,n,p combination of the resonance frequency in the microwave source frequency fluctuation scope, each combination represents one pattern which possibly exists in the cavity. After the computation we can obtain the m,n,p combinations under TE vibration pattern, they are (0,1,6),(0,2,3), (1,2,5), (4,1,5); The m,n,p combinations under TM vibration pattern are (1,1,6), (1,2,3), (2,1,5), (4,1,1). Namely there are 8 kinds of vibration patterns in the cavity, they are: TE016, TE023, TE125, TE415, TM116, TM123, TM215, TM411. So we can obtain the result from above, the resonant cavity is theoretically suitable for microwave pyrogenation. And actually filter resonant cavity's volume is bigger, its shape more complex, and the beginnings and ends all have the cone-shape transition, so in the resonant cavity microwave vibration pattern should be more, which is extremely advantageous for the microwave pyrogenation.That theoretics guarantee the feasibility of the experimentation, they is the base of the experimentation. Only on the base of it, our experimentation is feasible and significative. And then in the direction of the microwave calefaction theoretices, with the computer simulation software HFSS which is base on the finite element method, we optimize the microwave calefaction cavity of new depurant for epilogue form diesel engine, and design the microwave calefaction cavity of new air depurant.The last result prove that this kind of the transplant of technology is feasible and significative. It find a way which this technology can be used in other domains in.