الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Evaluation of engine vibration levels due to the change in some operating conditions represents a step to diagnosis comfort performance of the engine. In the present work an experimental test rig was prepared for the aim of prediction of engine performance (power, speed, break specific fuel consumption) and engine vibration levels due to the use different types of spark plugs and different types of fuels. Engines have been equipped for testing with different measurement devices such as tachometer, energy analyzer, noise meter, fuel consumption indicator and vibration sensor (accelerometer). Effect of changing five types of spark plugs (one, two, three, four electrodes and surface discharge type with no electrode) and resulting vibration levels on engine performance was studied. Also different types of fuels (natural gas and gasoline with different octane number) were used to evaluate the effect of changing these variables on engine performance and the resulting vibration levels. Single electrode shows the lowest fuel consumption and low vibration level due to low heat losses from the ground electrode compared with the multi electrode which causes higher percentage of heat losses and high level of cycle to cycle variation. Gasoline with octane number 92 shows the best performance and low vibration levels. Quadratic polynomial based on response surface methodology were proposed to predict the vibration levels verses the power, speed and time rate of fuel consumption.