The Study On The Fractal Property Of Combustion Flame Of SI Engine

Fractal is a new subject. The theories of fractal have been applied on the study of turbulence flame of internal combustion engine in recent years, which is a new research-strend for analysing the combustion processing of engine. Fractal theories can be used to analyse the burning of turbulence flame, from which we can abstract fractal dimension as charactericstic information, and then mass combustion rate is calculated. This article firstly gives a comprehensive review on combustion models of SI(spark ignited) engine, starts the study with the rate of turbulence flame and introduces a new method that fractal theories are used to research quasi-dimensional combustion models. Then the theories of fractal are introduced and the parameters, which are used in making up combustion fractal model of SI engine, are analysed.The author made the combustion flame of SI engine as the object of study and did some experiments for a study by applying the theories of fractal. Many works as follows were done for this sudy. The ChunFeng 172-Type engine cooled by water was redesigned to a optics engine, which had an eletronic injector and whose ignition advance angle was changeable. And it could also control the temperature of coolant exactly. Author developed an ECU used to control high-speed vidicon in order to synchronally shoot. The digital images taken by high-speed vidicon were pre-processed. Author programmed about how to calculate fractal dimension of combustion flame.By processing the images taken by high-speed vidicon, the following results can be got. The end-maximum scale and end-minimum scale of flame dimension are separately 13.08 millimeters and 0.84 millimeters. After the shock-point, the more ignition advance angle, the larger fractal dimension. If ethanol is in large proportion of mixture, the effect of combustion will be bad. Fractal dimension is in proportion to the rotate speed of engine when the speed is between 650 to 1050 rpm. When the mixture is thicker, fractal dimension of combustion flame will become larger.