![]() #DIESEL AIR DAIR 100 CODE#A customized version of KIVA-3V is used for the 3D-CFD cylinder analyses, while a commercial 1D-CFD code is employed to model the whole engine. Differently from previous papers published on the same engine, the current study is focused on two crucial design topics: the optimization of the supercharging system and of the injection strategy. The crankshaft can be directly coupled to the propeller, thanks to its excellent balance and the relatively low maximum engine speed (2600 rpm). Two mechanical superchargers are serially connected to the turbochargers. The scavenging system is of the Uniflow type, with exhaust poppet valves and a set of piston-controlled ports along the cylinder liner. The paper presents a CFD optimization of a turbocharged 2S CI 5.6 L flat-six aircraft engine developed by CMD. However, the design of these engines must be deeply revised, in order to incorporate the recent technologies, and it must be optimized with the support of CAE tools. In a modern light aircraft, these advantages still remain, along with the capability to run on jet fuel instead of gasoline. Two-Stroke (2S) Compression Ignition (CI) engines have been used in aviation since World War II, for their excellent fuel efficiency and lightweight construction. For the two best configurations, the most interesting calculation results are presented in the paper Then, several combustion simulations have been run, for defining two chambers able to match the project goals (high fuel efficiency, limited in-cylinder peak-pressure). A first set of KIVA calculations has been performed, in order to characterize the scavenging and the port flow patterns of both configurations, considering three different operating conditions, representative an aircraft engine. A development of both projects has been performed through a coupled 1d-3d computational approach. Two types of combustion-scavenging system have been considered, both of them featuring direct injection: a configuration with exhaust poppet valves and another one with piston controlled ports. Multidimensional calculations have been supported by 1D engine cycle analyses, using GT-Power. In this paper, a customized version of the KIVA-3v code (a CFD program for multidimensional analyses) has been used to address ports and combustion chamber design of a new project (a 3-cylinder 1.8L engine, with a power rating up to 150 HP). However, the coupling of 2-Stroke cycle and Diesel combustion on small bore, high speed engines is quite complex, requiring a suitable support from CFD simulation. Furthermore, Diesel combustion is a good match for supercharging and it is expected to provide a superior fuel efficiency, in comparison to S.I. The main advantage yielded by the 2-Stroke cycle is the possibility to achieve high power density at low crankshaft speed, allowing the propeller to be directly coupled to the engine, without a reduction drive. One of the most promising applications is on light aircraft piston engines, typically designed to provide a top brake power of 100-200 HP with a relatively low weight. In recent years, interest has been growing in the 2-Stroke Diesel cycle, coupled to high speed engines. ![]()
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