A CFD numerical calculation model was established to simulate the flow and purifying effect of a diesel urea selective catalytic reduction (SCR) system with different porous tubes at the front end of the catalytic converter. Effects of different porous pipe structures on pressure distribution and loss

flow field distribution

ammonia uniformity and NOx conversion rate were analyzed under the conditions of A25 and rated load respectively. Results show that the influence of the addition of porous tubes and different porous tube structures on the flow field and catalytic characteristics of the SCR system is different

in which the porous tube Ⅱ has the most obvious influence on the flow field distribution and pressure loss

ammonia uniformity and NOx conversion rate

resulting in a pressure loss of 1.2 kPa and NOx conversion rate increase of about 8% .The numerical error between the test result and the simulation calculation is in a reasonable range

which verifies the accuracy of the simulation calculation and the rationality of the structure design.