Integrated Research On Soot Trapping And Low Pressure Difference Muffler

In this paper, particles trapping and low pressure difference muffler integration wasresearched. Ensure that the exhaust back pressure is low and under the silencerrequirements, the way of improving the efficiency of particle collection was in research.The main research works are focused on the following aspects:(1) Research on trapping performance of soot particlesThe trapping mechanism of porous media was analyzed. Structural parameters ofporous ceramics, force of particles and trapping mechanism were analyzed. Combined withexisting research finding as well as the relationships between various parameters andtrapping efficiency, the structural parameters of ceramic foam were determined. Based onthe requirements of these studies, various equipment and instruments were reasonablyselected. The particles trapping efficiency experiments were made after making trappingdevices and connecting them to the testing bench.10PPI and25PPI two kinds of ceramic foam models trapping performance andbackpressure were comparatively tested. And then25PPI foam ceramic in different pitchcombinations were tested. Experimental findings were obtained. The relationships betweenthe ceramic foam models, thickness and spacing and the trapping rate and the exhaustback-pressure were achieved.(2) Research on acoustic attenuation performance of trapping device10PPI, the thickness of42mm and25PPI, the thickness of46mm foam ceramic ofacoustical absorption coefficient were studied with standing wave tube method, obtainedtwo kinds of foam ceramic acoustical absorption coefficient. Based on the relationship ofacoustical absorption coefficient and acoustical transmission coefficient, the correspondingacoustical transmission coefficient was gained. Based on foam ceramic had been obtainedby two kinds of test data model, acoustic attenuation performance was further studied withnumerical simulation method in two kinds of ceramic foam. Effects of different pitch combinations foam ceramic pairs of trap muffler performance were studied as well.(3) Research on acoustic attenuation performance of drumlike silencerThe effects on acoustic attenuation performance of tube radius, cavity diameter, massper unit area diaphragm, diaphragm length, per unit length parameters membrane tensionon the drumlike silencer with numerical simulation were studied. As well as differentthickness, different materials of membranes were studied. Finally based on research resultsand the application, the reasonable size and structure of membrane materials were selected.(4) Integrated research on trapping device and silencerThe porous ceramic components, drumlike silencer geometry parameters, and therelationship between the relative positions and the porous ceramic components weredetermined by contrast optimization. Achieving the guaranteed amount available of theacoustic attenuation performance, the pressure loss was reduced and the efficiency ofparticle trapping was improved.Through the trapping performance studies, the effects of trapping performance withdifferent PPI, different thickness, different spacing of the porous ceramic were achieved.As well with the trapping performance improvement, it brought about the improvement ofthe exhaust back pressure and power loss increased. Through the research on on acousticattenuation performance of trapping device, the effects on acoustic attenuationperformance of10PPI and25PPI ceramic foam models, as well as distance between pairsof ceramic foam were obtained. Through the research on acoustic attenuation performanceof drumlike silencer, the effects on acoustic attenuation performance of tube radius, cavitydiameter, mass per unit area membrane, membrane length, per unit length parameters suchas membrane tension on the drumlike silencer with numerical simulation were studied. Aswell different thickness, different materials of membrane were got. Finally based on theresearches and engineering practice, the reasonable size and structure of membranematerials were selected.Eventually considering the soot trapping performance, the acoustic attenuationperformance of trapping device, the acoustic attenuation performance of drumlike silencerand changes in the engine exhaust back pressure and power losses, the design of trappingdevice and low pressure silencer were made.