【作者】

Martin Wyzgala，Peter Boehm，Dietmar Pinkernell

【摘要】

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。 Diesel and gas engines are considerably excited to structural vibrations by enormous forces caused primarily of fuel combustion and moved crank drive masses. Customers and classification societies demand low vibration engines. At MAN Diesel& Turbo(MDT), the engine vibration is limited to an acceptable level by purposive measures regarding the engine design already during concept and detail design phase-long before the first engine test and measurements are possible. Front loading by virtual engineering plays an essential role in the development process of diesel and gas engines. By combining engineering tools for analysis, simulation and optimization, virtual engineering facilitates a multidisciplinary and result-oriented product development. It supports classical design approaches as well as traditional experimental testing and validation. Virtual engineering assists the development process from the very first design idea to the final validation of the product. MDT demonstrates successful front-loading by means of the exemplary resiliently mounted 20V 35/44G engine, its latest four-stroke medium speed gas engine for power plant applications. MD T designs a low vibration engine, even though facing new, challenging boundary conditions such as high mechanical efficiency, higher firing pressures, light-weight design. In addition to topology optimization of the crankcase and an investigation of different firing sequences, an essential element in vibration optimization is a highly advancedvibration analysis and simulation process delivering accurate, reliable and predictive results. The vibrations of entire engines are investigated by means of Finite Element simulations and appropriate shell models. Because of its comparably small size and their parametric properties an evaluation of a high number of design variants within an admissibly short time is feasible. The simplification of the complex solid geometries to a mid face design of a shell model inevitably implicates deviations. However an optimum quality of the simulation model is indispensible. There-fore an updating procedure on numerical basis is introduced, which is already performed by standard long before any engine part is available in hardware for an experimental modal analysis. Moreover the numerical method offers equivalent results, that a late and ex-pensive test of core assemblies is not required. Each derived model of a core part e.g. the crankcase, base frame and turbo charger attachment is updated with respect to its original structural properties. The updating is carried out once firstly by correlating modal results like eigenfrequencies and mode shapes of reference solid FE models and their corresponding shell models and finally by adjusting parameters such asmaterial properties, element thickness or mesh density. More detailed information about the model updating procedure will be given by the paper. Due to cer-tain tolerances of boundary conditions, such as damping, non-linearity and fabrication tolerances, local inaccuracies will always exist. Local systems can react not exactly as predicted. Nevertheless MDT is conscious of these remaining, local inaccuracies and taking them into account already during the concept and detail design phase. Local design alternatives are de-termined by help of the vibration simulation and hold available for testing. If necessary, the appropriate solution is chosen and verified by measurement. High costs and long testing periods for the product validation are avoided. Finally the comparison of simulation and measurement results received later from the test bed illustrates, that the simulation has an excellent quality and accuracy. Having established the presented simulation process, MDT possesses the proper methods and tools respectively know-how, in order to cope with the ambitious engine design demands.This ends up in a low vibration design of new medium speed engines taking car

【会议名称】

第27届CIMAC会议

【会议地点】

上海

【下载次数】

1

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