Development And Research Of Marine Diesel Engine Operating Parameters Acquisition And Analysis System

Data acquisition system is useful for analyzing the status and performance on diesel engine,espiecialy in evaluating the quality of combustion process. For the two-stroke low-speed marine diesel engines and four-stroke diesel engine, a computer-controlled parameter acquisition and analysis systems is developed. Through selecting the cylinder pressure sensors,charge amplifiers, high-speed data acquisition card, optical encoders, thermocouples,temperature conversion module, a data acquisition hardware system is built. A software system based on windows operating system is developed with Visual Basic software.Hardware and software systems adjustment has completed on the engine platform.Acquisition parameters includes cylinder pressure, exhaust gas temperature, diesel engine speed and so on.FIFO technology is adopted in the diesel parameter acquisition and analysis program to achieve real-time synchronization of the cylinder pressure data collection, save and graphic display. Pressure variation rate and heat release rate calculated based on cylinder pressure data.By converting the crank angle to the cylinder volume P-V indicator diagram achieved. All paramters acquisited can be saved in the database developped on the Access modle.In addition,the functions of the coordinate display and playback developed for the purpose of data viewing and pickup.Noise removing from normal signal is important and difficult during the indicator diagram preprocess. Through Fourier transfer on indicator diagram, it shows that there is channel effect in the indicator diagram, and the noise frequency band is mainly concentrated on from high to mid ranges in spectrogram. Signal processing methods such as cubical smoothing algorithm with five-point approximation,butterworth low-pass filtering and wavelet analysis are compared. The results showed that: wavelet analysis method can effectively remove the noise,and filtering result is better than low-pass filtering and cubical smoothing algorithm with five-point approximation.Through platform test on Marine diesel engine at low speed, as well as 4135 diesel engine at moderate power, the availability of this system is verified. The results showed that the Marine diesel engine parameter acquisition analysis system friendly for operators, can be used to analyze the Marine diesel engine cylinder pressure change process and combustion process.