The objective is to provide a tested computer-based method which will assist the design of the manifold, port-valve assembly and injectors of four valve engines and to quantify the effects of injection timing. The method will be designed to deal with steady operation of engines and with transients such as those experienced in every day operation. Extensive supporting experiments will also consider transients, with consequent need to improve measurement techniques, and the engine configurations will be arranged to operate with rapid and controlled variations in speed and load.
The final product will be a tested computer programme with new models to represent the two-phase flows which occur within the manifolds, ports and cylinders of engines operating under steady and transient conditions. Thus it will be necessary to conduct experiments to provide the basis for the new models and to allow the verification of the computer programme. The research will, therefore, have several components.
Techniques will be developed for the measurement of droplet and liquid-film characteristics during rapid transients of a turbulent flow, and used to examine the two-phase flows in the port-valve regions and the downstream cylinder of a purpose-built transparent head and downstream of two four-valve cylinder heads one with isothermal flow, and the other on an operating engine. The results will provide guidelines for future control by engine management systems as well as forming the basis for models which will be formulated to represent the measurements and for incorporation into the SPEED-STAR computer programme. Experiments in a manifold will be represented by a one-dimensional method which will be linked to the computer programme which will then be used for calculations for the complete engine cycle and from manifold to exhaust.
Expected Achievements and Exploitation
The final result of the research will be a computer programme which will be used in the design of injection strategies for spark-ignition engines with liquid fuel sprayed into the ports. The programme will be based on measurements of droplet characteristics in the port, valve gap and engine from intake to ignition so that a substantial body of new information of atomization, evaporation and mixing of the fuel and air will be available to the designer. This information of droplets will be available as a function of injector type and injection timing, and linked to measurements of engine performance. Thus, the consequence of injection strategies on mean effective pressure, drivability and emissions will be known for a typical four-valve engine under steady-state and transient operation. The computer programme and measured data will be used directly by Fiat and Peugeot in the development of their port-injected engines.
Funding SchemeCSC - Cost-sharing contracts
10043 Orbassano Torino
92852 Rueil Malmaison