Study On Numerical Simulation And Experiment Of Spark-arresting Silencer Characteristics

Spark-arresting silencer is a secure device fixed in the exhaust pipeline of internal combustion engines, which allows the exhaust airflow to pass and prevents the flame, spark and noise from propagating. It is suitable for the flammable and explosive place.This thesis uses the standard k-εmodel and DPM model in Fluent to investigate the gas-granule two-phase flowability in the silencer, and to calculate the gas-phase flow as well as to comprehensively analyze gas-phase flow filed with the existing model and boundary conditions. The distributing rule of axial velocity, radial velocity and circumference velocity in different positions of silencer is got, and the effect of silencer inlet velocity on the pressure loss is further analyzed. The mechanism of Spark-arresting inside silencer is showed and the effects of manipulation parameter on spark-arresting efficiency under experimentation condition, actual condition and different structures are respectively discussed by utilizing Lagrange method of bidirectional coupling to track particle trajectory.A test-bed for measuring spark-arresting efficiency and pressure loss is designed and set up. Comparisons of experimental results with numerical results show that the pressure loss results of the two kinds of methods are similar, accordingly demonstrate the correctness of numerical calculus method. The spark-arresting efficiency curves of experiment and numerical calculus have the same variational current; however the results have a little difference which shows that the numerical calculus method still has a degree of error in the calculation of gas-granule two-phase flow.The inner acoustic field and the transmission loss of silencers are calculated and analyzed by using the finite element method in SYSNOISE software, and the influence of different structures on the transmission loss is discussed also. A test-bed for silencer acoustic performance is designed and set up. The sound source and microphones are arranged reasonably. The two-load method is used to measure the transmission loss, and the experimental results agree well with the simulation results, indicating that that the experimental method is valid.