A Study Of Influence On Engine Vibration Characteristics Burning Coal Based Fischer-Tropsch Mixed Fuel

Thanks to its high efficiency,large power and good economy,diesel engine can be widely used in the production of industrial and agricultural products.However,the problem of energy consumption that we are facing at present undoubtedly buries hidden trouble for the future of diesel engine.While F-T diesel,as a substitute fuel for diesel engine,can effectively reduce NOx emission because of its high cetane number.But at the same time,the problem of soot emission rising is also a problem.On the other hand,because the combustion process of the diesel engine is closely related to its power,emission and economic performance of the diesel engine,the working state of the diesel engine can be detected in time so as to make the diesel engine work in a comparatively ideal state.The vibration signal method is convenient to measure the engine state.And the most important thing is that the cylinder head vibration signal contains abundant combustion state information.Therefore,the evaluation of engine combustion state based on engine vibration signal has practical value.In this paper,F-T diesel fuel mixed with methanol and butanol with 10% volume ratio is used,named M10 and D10.The effect of the physical and chemical characteristics of the fuel on the vibration characteristics of the diesel engine is analyzed by the bench test.And the relationship between the waveform of the filtered vibration acceleration signal and the pressure rise acceleration and the cylinder pressure curve is analyzed.Then the combustion characteristic parameters are extracted by the vibration acceleration signal of the diesel engine.The main conclusions are as follows:(1)Under different working conditions,the energy of the internal pressure spectrum of the diesel engine is mainly concentrated within 0~10 kHz,and the amplitude of the cylinder pressure level of the F-T fuel and the mixed fuel M10 and D10 is lower than 0# diesel fuel,and the corresponding frequency range is also less than 0# diesel;The dimensionless characteristic parameter value of 0# diesel oil is the largest,the parameter value of F-T diesel fuel is the least,the mixed fuel is between the two,and the corresponding dimensionless characteristic parameter 0# diesel fuel is the minimum,and F-T diesel fuel is the maximum,M10 and D10 of the F-T diesel fuel are between the two;In the main vibration frequency region of the diesel engine,the vibration duration of 0# diesel is the longest,and the F-T diesel fuel is shortest,M10 and D10 diesel fuel are between the two;Under different working conditions,the vibration energy inrelation to in-cylinder combustion of the four kinds of fuel is mainly in the frequency band of 0~2100 Hz,and the vibration acceleration power spectrum density of the cylinder head of 0# diesel oil is the largest,M10 and D10 is the second,and F-T is the least.(2)Using the filtered vibration acceleration signal to identify the partial characteristic parameters of the in-cylinder combustion state: the first peak point can estimate the start point of the combustion,and the first lowest point estimates the peak point of the high rate of the pressure,the third peak point can estimate the moment at which the peak pressure appears.Then the estimated parameter value is compared with the characteristic parameter value measured by the bench test,founding the time of combustion starting point estimated,the peak pressure rise rate and the time of cylinder pressure peak estimated is between-2.1?A~1.7?A,-2.5 ?A~1.5 ?A and-3.0 ?A~0.7 ?A.(3)When the diesel engine is under the same working condition,the combustion characteristics of several fuels are analyzed based on the vibration acceleration signal.The combustion starting point of the F-T diesel fuel is much earlier than that of the 0# diesel fuel,M10 and D10 is delayed than that of the F-T diesel fuel,and the performance of the mixed fuel M10 and D10 is more obvious than that of the F-T diesel fuel low load,and the starting point of 0# Diesel appears at the latest;The peak phase of pressure rise rate of F-T and M10 and D10 is earlier than that of 0# diesel,while the F-T diesel fuel is lagging behind both mixed fuels;Compared with the peak phase of cylinder pressure of 0# diesel,both the F-T diesel oil and the mixed fuel M10 and D10 have been delayed.