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An extensive amount of research has been carried out by various authors on the entrainment of fuel droplets in a steady air flow, in order to understand the transportation of droplet fuel in the spark-ignition engine intake manifold system. However, the utility of this type of steady state model is very limited when applied to the real engine where the air flow is highly pulsative. The present work develops a theoretical model of the flow of fuel droplets entrained in a non-steady air flow which requires the solution of a set of unsteady one-dimensional two phase flow equations by a numerical technique. This model is then applied to a single-cylinder spark-ignition engine fitted with both intake and exhaust manifold systems and also a carburettor.

A numerical scheme for a Computer Aided Design (CAD) package for the design and development of internal combustion engine intake and exhaust manifold is presented. The program is interactive and uses the graphical and visual display unit (VDU) facilities extensively. The basic concept of such a program was described in a previous SAE paper (Paper No. 790277) by one of the authors (SCL). The present program is written to handle a maximum of 10 cylinders and any imaginable configuration of intake and exhaust manifold. The input data, the preparation of which is usually a time-consuming process, are kept at a possible minimum with automatic generation of data from arbitrary drawings drawn manually on the VDU screen. The program is applied to a commercial 4 cylinder - 4 stroke spark ignition engine.

An interactive computer program for predicting the performance of a total engine system is described. The facilities include the basic design of the valve time-area diagrams, starting from various cam profiles, wave action effects in inlet and exhaust manifolds and turbocharger matching. The program is accessed via visual display units (VDUs) and its interactive nature takes many activities from the realm of the research department into that of the design department. The results obtained from the program are validated by comparison with a well-known more sophisticated wave action program.