Research Of A Void Filling Algorithm Based On Feature Recognition And Its Application To MCAM

Monte-Carlo particle transport simulation Automatic Modeling system(MCAM) develiped by FDS is an interface program and an integrated modeling system implementing the bi-directional conversion between CAD model and MC simulation model and supports a series of supplementary functions such as creation and repair of CAD model and analysis of physics properties for Monte-Carlo model. CAD engineering model only defines the actual component parts, while it's necessary to define the entire problem space for the Monte Carlo particle simulation model, so the spare part which do not belong to any part(the cavity ) also needs to be described such as hollow part of the pipe model.Meanwhile, it is err-prone and inefficient to manually create the cavity description of a CAD model with a large number of pipes. At present, although Boolean subtraction algorithm can be used to construct the cavity description of CAD model in MCAM, but it is not intellective and the result is too complex. Therefore, it is an urgent to develop a new void filling algorithm.Through the research of the geometry and topology of CAD model, this paper presents a new method based on feature recognition technology for the void filling of CAD model, and implements the automatic modeling of cavity and pipeline in CAD model. On the basis of study of algorithms, void filling function that can handle models with a large number of pipes in CAD model were developed based on MCAM. Some representative test models were employed to perform the strictly test and validation of the related algorithms and functions.The void filling function of MCAM was applied to the pipes model of ITER (International Thermonuclear Experimental Reactor) model. The complete and accurate cavity CAD model was created. The calculation result of Monte Carlo particle simulation code MCNP showed that, the computational efficiency was greatly improved compared with the original model created by Boolean subtraction method. The successful application of void filling algorithm and function demonstrates the feasibility and validity; moreover, it has solved the inefficient problem of MCAM for handling pipelines.