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This thesis presents research work which is concerned with the development of analytical and numerical methods for the dynamic analysis of the crankshaft-crankcase assembly. The effects of interaction of crankshaft and crankcase on the dynamic response of an IC engine block structure are studied. These methods are especially attractive for the simulation of the steady state response of rotating systems with many degrees of freedom which are forced by multiple periodic excitations. A major novelty of the methods is the ability to model the system non-linearities successfully as frequency dependent properties.

Two mathematical models have been developed to simulate two-dimensional, premixed, laminar, stationary, axisymmetric methane-air flames, and successfully validated with non-intrusive Coherent Anti-Stokes Raman Spectroscopy (CARS) temperature measurements. With the first model, the heat releaser ate model, volumetric heat release rate was generalised from one-dimensional computations. This approximation greatly simplified the set of governing equations that need to be solved. However, it cannot describe the effects of high stretch rates or of negative stretch rate. The second model made use of a number of reduced chemical kinetic schemes, with realistic elementary reactions. These were drawn from the literature and realistic transport properties have been included. With this model, based on the work of Peters (1985), the effects of stretch are automatically accounted for. Practical experimental validation was obtained with a multiple slot burner, supplied by the collaborating body, British Gas p1c. Temperature fields, obtained with the CARS technique, partially validated the reduced chemical kinetic scheme model. Some uncertainty arose in the prediction of heat loss to the burner tube. A numerical algorithm based upon the SUVIPLE method was employed,with a fully staggered grid. Various discretisation schemes were examined with the heat release model. Based on these tests, the hybrid scheme was selected for use in the reduced model. With this approach, a few reduced kinetic schemes have been selected and implemented. The most successfuol ne was the Peters( 1985) scheme. This consisted of 4 global reaction steps with 18 elementary reactions and 7 non-steady chemical species. The scheme has been employed in all the detailed computations in the present study. With this scheme, two-dimensional field solutions, for methane-air mixtures with equivalence ratios of 0.75,0.84 and 1.0, with slot widths of 2 mm, and 3 mm, and mean inlet velocities ranging from 0.3 m/s to 2.8 m/s have been obtained. Detailed flame structures have been obtained for all these conditions. Under these conditions, a number of parameters, essential in burner design and stability analysis, have been investigated. These includes flame height, flame thickness, and heat loss to the burner tube. The loss can range between 3% and 32% of the chemical energy in the premixture. The computations reveal the stretch rates acting on the flame and their effects on the burning velocity. At low flow rates the base of the flame has a negative stretch rate, while the flame tip is positively stretched. These effects are reversed at high flow rates. From the localised relationships between stretch rate and burning velocity, Markstein lengths have been evaluated,for different mixtures and the values compared with those obtained experimentally by other researchers. In general, there was good agreement despite the large scatter in the experimental values. The results further showed that the effects of the two components of flame stretch, namely flame curvature and aerodynamic straining, on burning velocities were very different. It seems appropriate to introduce two Markstein lengths to correlate burning velocity and the two components of stretch and these have been evaluated. Aerodynamic straining has a significantly larger effect on burning velocity than has flame curvature.

One of the most important source of noise and vibrations associated with vehicles is the vibration of driveline systems. Such phenomena are subjectively associated with customer complaints. In this study the torsional vibrations of driveline systems were investigated using discretised and lumped mass models of the system. In the literature, many of the problems associated with torsional vibrations and refinement in drivelines have been tackled through relatively simple, lumped mass models combinedw ith experimentalm easurements. However, some problems remain particularly where instabilities occur or complex coupling with other vehicle vibration modes exists. The review of previous work showed that although it is important to understand the dynamic behaviour of the individual driveline components; for example, engine, clutch, gearbox, etc., the whole system must be analysed together because of all the coupling which occurs. The main source of excitation for torsional vibration of the driveline system is the engine fluctuating torque. A computer program using MATLAB subroutines was developed to obtain this fluctuation torque for different engine parameters for subsequent use in the modelling. A substructure approach, using stiffness coupling technique with combined use of residual flexibility and modal synthesis, was used to analyse free and forced vibrations of the system, as a linear system. A computer program using MATLAB subroutines was designed to facilitate application of this technique. Good agreement between results for the overall system model and substructure model was found even for a few considered modes. This substructure technique offers significant computational advantages over other methods. The effect of non-linear sources in the driveline system such as backlash, non-linear spring stifffiess, Hooke's joint and angularity of the propeller shaft on the system torsional vibrations was investigated. The effect of backlash in the driveline system was significant and, as expected, vibration levels increased as backlash increased. Hooke's joints caused an additional complex source of excitation but their significance is dictated by the details of the particular driveline design. The modelling showed that instabilities commonly referred to a shunt or shuffle could occur during clutch engagement. The stick slip frictional properties of the clutch were crucial in this behaviour and the relative importance of various design features was quantified. A mathematical model including torsional motion of the driveline system and other vehicle body motions was developed to analyse the ways in which the driveline couples with other dynamic components. Two running conditions were considered; steady state running and transient during clutch engagement. It was shown that the complete system was capable of self-excited oscillations under certain conditions during normal running as well as the instability which could occur during clutch engagement. This comprehensive model represents an important contribution of the work in this area of research in two ways. First, it clarifies understanding of the dynamic coupling between the rotational and translational components of the whole vehicle system. Second, it provides design information to tackle instability problems and to lead to reductions in overall vibration levels.

The work presented in this thesis is concerned with developing a greater understanding of piston ring lubrication and consists of both experimental and theoretical components. It begins with a review of piston ring and ring pack lubrication studies, describing how the understanding of the operation of piston rings has progressed since the late 19th Century. A well-established method of analysing the hydrodynamic lubrication of a single piston ring, utilizing coordinate data to describe the ring face profile, is then presented. Calculation of mixed/boundary friction, when the lubricant film thickness falls below a pre-determined level, is included. The predictions of this program are then compared to results obtained by other workers to validate its operation. This analysis is then developed to investigate the influence of the circumferential variation in piston ring face profile on the lateral motion of the piston ring centre. The complex relationship between variation in ring face profile, angular ring gap position and bore shape is then examined. These features are shown to have a significant effect on the calculation of ring centre locus, oil transport and lubricant film thicknesses. The model is then applied to predict the influence of the distorted bore shape of a cylinder from an experimental engine apparatus. Following this, the development, testing, calibration and performance of a capacitance based measurement system capable of recording piston ring face profiles on a single pass, is described. This system was used with twenty-one transducers, of novel design, to allow the axial and circumferential distribution of lubricant film thickness to be monitored on an engine liner. This liner was fitted in an engine apparatus which had the additional facility of being able to measure the instantaneous friction between the piston assembly and cylinder liner using a "floating liner" technique. Experimental measurements of instantaneous friction force and the circumferential distribution of lubricant film thickness are then compared to theoretical predictions for a range of operating conditions. The comparisons reveal a reasonable level of agreement between measurements with consistent overall trends. The effect of varying bore distortion is also examined theoretically. It is shown that an increase in the severity of bore distortion does not necessarily result in an increase in net oil transport.

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