Determination of Kinetic Correction Coefficient of Fluid Flow Using a Generic Multiple Orifice Physical Scale Model Structure

Abstract

Problem statement: Diesel particulate filters are fast becoming integral parts of diesel engines, light and heavy duty, due to their potential in the reduction of particulate matter from exhaust gases and their noise muffling property. Consequently, several researchers are developing mathematical models for the study of fluid flow through the filter substrate and in the aiding of filter systems design. Recently, some researchers developed a mathematical model known as the Multiple Orifice Mathematical (MOM) model for determining pressure gradients of gelcast ceramic foams. The MOM model was calibrated using fluid flow data from cellular foam filter structure similar to ceramic foams. However, there was need to improve on the method of calibrating the model. Approach: Following the conceptual model employed in the development of the MOM model, a physical scale model was designed using a CAD package and manufactured for the purpose of measuring pressure drops across the connecting windows of the cells. A new fluid flow rig was also designed from a CAD package and fabricated to adapt to the physical scale model. Applying the conservation theory, the flow rates across the windows were calculated and equated to the flow rate determined from an orifice meter, where the correction coefficients for the calibration of the MOM model were calculated. Results: A number of correction coefficients were calculated from the data collected from the experimental rig. The average correction coefficient which was used for the calibration of the MOM model was found to be 2.24. Conclusion/Recommendations: The result obtained from the new method of model calibration corroborated the value determined by earlier researchers. This new method reduced the computational time of calibrating the MOM model and eliminates the use of graphs and graph fitting. The new fluid flow rig and the physical scale model can be used in the study of fluid flow in other types of filter substrates.