Simulation And Testing Studies On Pressure Loss Of Exhaust Muffler

Pressure loss is one of important factors in evaluating muffler performance, which is related to power loss of engine directed. In order to improve fluid dynamics performance, to decrease pressure loss of muffler, the influence of flow velocity and dimension character parameters for pressure loss of several basic muffler elements was studied with the way of simulation analysis and test.Using the computational fluid dynamics (CFD) software CFX, this paper researched on pressure loss for expand muffler elements with expand ratio, expand length, inlet diameter, insert muffler elements with insert pattern, perforated muffler element with perforated ratio, perforated diameter, and perforated plate muffler elements with perforated ratio, perforated diameter,the location of perforated plate. The results show that: the pressure loss of muffler elements increased dramatically with the inlet velocity increased. And the expand muffler elements have a critical expand ratio, whose pressure loss is most. The critical expand ratio increases with the expand length lengthening. The longer the expand length is, the smaller the inlet diameter is, the greater the pressure loss of expand muffler element is. The pressure loss of coaxial insert muffler elements decreases with the total insert length of inlet and outlet increased. The pressure loss of non-coaxial insert muffler elements increases with the insert length of outlet increased. The pressure loss of concentric perforated muffler elements increases with the perforated diameter increased. The pressure loss of perforation expand, perforation shrink and perforation plate muffler elements decreased with the perforated ratio increased, then keeps steadiness, and the perforated diameter has little influence to the pressure loss of perforation muffler elements. With the help of simulation results, the reason of pressure loss was discussed briefly.The pressure loss of some muffler elements were measured, the result of test is closed to the result of simulation. The software of CFX is fit to research on the fluid dynamics performance and pressure loss efficiently for muffler, and to analyze dynamics performance and predicting pressure loss of muffler.Used the CFX software, a vehicle muffler flow field was analyzed, and fluid dynamics performance was evaluated. The reason which pressure loss is high was found by the results of simulation. Combined with the research results, some improved measures were brought up, the pressure loss of improved muffler decreased by 30%.