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Simulations have been carried out for the flow through a throttle valve to determine the flow mechanisms for various blade angles. In all cases, the time-dependence of the flow had to be accounted for. From this the relationship between blade angle and frequency of oscillation has been found. Comparisons have also been made between solutions with tetrahedral unstructured meshes and hexahedral structured meshes. Finally, it has been found that adding a breather pipe to the throttle removes the oscillation entirely.

The steady flow through a plenum-runner system within an inlet manifold has been measured experimentally and also predicted with computational fluid dynamics (CFD). This paper reviews the experiment and computation before presenting the results of simulations that assess the effect of various geometries at the plenum-runner interface. It has been found that careful experiments are needed to produce reliable experimental data and that CFD can be used to produce accurate predictions. In terms of the losses due to various interfaces, the sharp-edged simple interface is the worst case, with a protrusion giving a slight reduction in loss and various forms of rounding significantly reducing the losses.

Jaguar has developed a new V8 powertrain with the support of predictive design analysis techniques. This paper describes some of the work performed during this programme to ensure low frequency powertrain refinement. The concept of the engine was to produce a lightweight 4.0 litre engine with class leading specific torque and power, while satisfying customer aspirations for vehicle refinement. To meet the refinement objectives, an understanding of the structural dynamic performance of the powertrain was required. This understanding would be essential in developing the design from initial concept through to production intent. To support this requirement a programme of predictive work was included within the design plan. In the predictive work, low frequency modes of the powertrain and order tracked mount vibration were used to characterise the influence on in-vehicle refinement. Comparison with measured engine vibration confirmed the predicted effects of design changes.

For Computational Fluid Dynamics (CFD) to be influential in designing new engines, it has to be capable of providing useful design information to engineers in a short space of time. It is usual for several months to elapse from the time it is first decided to carry out a CFD simulation to obtaining the results. This is not acceptable and a target simulation turnaround time of one day is more appropriate. This work has investigated ways in which computational models, and especially meshes, can be built quickly both using commercial software and software written in-house. Simulations using these models have been carried out and this study shows that models with distorted cells can be built with ease by one person in a few days. Some current generation flow simulation packages cannot produce results using these models, but models with acceptable distortion are now built routinely and solved within two weeks.