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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.

In the laboratory of Machines at the university of Gent a multi-point liquid LPG fuel injection system has been developed. The tests have shown that the LPG injection system works perfectly for all speed and load conditions of the engine. The advantages of LPG are confirmed with the tests: prevention of knock at high compression ratios, less exhaust gas pollutants. The tests were carried out on a standard Ford gasoline (injection) engine. Comparative tests are presented for the gasoline engine, the engine with an evaporation system (LPG and butane as fuels) and for the engine with the LPG injection system. Then a parametric study of the LPG injection engine has been done (ignition timing, air-fuel ratio, compression ratio). The influences of these parameters on the engine characteristics are given (influences on power output, efficiency, fuel consumption, NOX concentration). A remarkable increase in the power output when the compression ratio is increased is noted.

In previous papers a complete simulation model of the combustion in a gasoline rotary engine has been described. This combustion model, developed at the University of Gent and UMIST (University of Manchester Institute of Science and Technology), is based on a turbulence enhancement factor for the flame in various zones of the combustion chamber. The purpose of this paper is to give a description of the modifications of the model for a homogeneous natural gas rotary engine. The real geometry of the combustion chamber is incorporated In the model. Calculations are executed for different geometries of rotary engines (especially different positions and shapes of the recess in the rotor). Different formulas of the laminar flame speed for natural gas are examined. The turbulent flame speed is calculated with a turbulence factor or with a turbulence intensity factor. A correlation between the engine conditions and the turbulence intensity is proposed.

A detailed three-dimensional study of the mean flow and the turbulence inside the liner of a direct injection diesel engine under steady state flow conditions has been carried out by laser doppler anemometer measurements. The influence of the valve lift, the port orientation (using a cylinder head with variable direction of the inlet channel) and the mass flow on flow characteristics (kinetic energy distributions, momentum flux, swirl parameters) has been analysed. These flow characteristics have been used to analyse the relation between the real flow pattern and swirl parameters as measured by the flow rectifier method and the paddle wheel anemometer.

A water model has been used to determine the positions of separate inlet ports for a natural gas, stratified charge rotary engine. The flow inside the combustion chamber (mainly during the induction period) has been registered by a film camera. From these tests the best locations of the inlet ports have been obtained, a prototype of this engine has been built by Audi NSU and tested in the laboratories of the university of Gent. The results of these tests, for different stratification configurations, are given. These results are comparable with the best results obtained by Audi NSU for a homogeneous natural gas rotary engine.

An extensive experimental and analytical study of the performance of a Wankel engine is reported, with special emphasis on the combustion process. A one dimensional technique for calculating gas velocities in the combustion chamber under motoring conditions is described and this is then used to evaluate flame travel when combustion occurs. A novel three-zone combustion model is introduced. The effect of the position of the rotor recess is examined and shown to change the engine power output and hydrocarbon emissions.