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The volumetric efficiency of reciprocating internal combustion engines is a strong function of intake manifold configuration. A computationally efficient simulation technique is described which is based on the linearised one-dimensional conservation equations for distributed parameter systems and is amenable to the requirements of the designer in directly assessing the comparative merits of a large number of manifold configurations. Comparisons of measured and predicted volumetric efficiency curves are presented together with predicted results which illustrate the benefits to be obtained from variable geometry induction systems. The technique was found to be over 220 times faster than a comprehensive simulation program based on the method of characteristics.

This paper describes a comparison between calculated and measured pressure traces and air mass flows through a family of inlet manifold geometries. It is shown that a non-linear wave action calculation technique, based on the method of characteristics, can accurately predict the detailed variation of pressure in the manifold over a broad range of engine speed: it can also accurately predict the mass flow. It is shown that it is necessary to include end effects for the various pipes in order to obtain realistic predictions. The mass flow can be predicted to better than 2% over the majority of the engine operating speed, although the accuracy decreases slightly at the tuning speeds. This reduction in accuracy is probably due to the increased losses resulting from the higher velocities and flow reversals occurring at the tuned speeds.

The improvement of exhaust emission during engine warm-ups is vital in engine emission control as engine emission limits are constantly lowered. An effective solution to this problem is to install a rapid-warming catalyst. On the other hand, precaution also has to be taken to avoid overheating of the catalyst. These require detailed information on heat transfer and accurate gas temperature variations at different locations in the exhaust system. In this study, experiment was conducted to investigate how mean gas and pipe wall temperatures vary during warm-ups throughout the exhaust systems, as well as the time constants of the transient processes. In addition, a program was developed for the simulation of exhaust gas and pipe wall temperatures during warm-ups. The temperatures were time-averaged in every engine cycle but variable from cycle to cycle.

Computer programs that simulate the wave propagation phenomena involved in manifold tuning mechanisms are used extensively in the design and development of internal combustion engines. Most comprehensive engine simulation programs are based on the governing equations of one-dimensional gas flow as these provide a reasonable compromise between modelling accuracy and computational speed. The propagation of pressure waves through pipe junctions is, however, an intrinsically multi-dimensional phenomenon. The modelling of such junctions within a one-dimensional simulation represents a major challenge, since the geometry of the junction cannot be fully represented but can have a major influence on the flow. This paper introduces a new pressure-loss junction model which can mimic the directionality imposed by the angular relationship of the pipes forming a multi-pipe junction. A simple technique for estimating the pressure-loss data required by the model is also presented.

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.

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.

The propagation of pressure waves through junctions in engine manifolds is an intrinsically multi-dimensional phenomenon. In the present work an inviscid two-dimensional model has been applied to the simulation of shock-wave propagation through 45° and 90° junctions: the results are compared with schlieren images and measured pressure-time histories. The HLLC integral state Riemann solver is used in a shock-capturing finite volume scheme, with second-order accuracy achieved via slope limiters. The model can successfully predict the evolution of the wave fronts through the junctions and the high frequency pressure oscillations induced by the transverse reflections. The calculation time is such as to make it feasible for inclusion, as a local multi-dimensional region, within a one-dimensional wave-action engine simulation.

Computer programs to simulate the gas dynamics of internal combustion engines are commonly used by manufacturers to aid optimization. These programs are typically one-dimensional and complex flow features are included as ‘special’ boundaries. One such boundary is the ‘pressure-loss’ junction model, which allows the inclusion of directionality effects brought about by the geometry of a manifold junction. The pressure-loss junction model requires empirical, steady-flow pressure-loss data, which is both time consuming and expensive to obtain, and also requires the junction to be manufactured before its performance can be established. This paper presents a technique for estimating the steady-flow data, thus obviating the need to perform these flow-tests.