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Investigation of the Effects of Variable Valve Timing and Lift on Knock Limits of Spark Ignited Gasoline Engine

Rahatlooi, Rahele | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45547 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saeidi, Mohammad Hasan; Hosseini, Vahid
  7. Abstract:
  8. Knock is an abnormal phenomena in combustion engines and one the main limiter elements in increasing engine efficiency. From years ago, recognition and elimination of this phenomenon had studied by investigators and various approaches to anticipation had presented. One of the newest methods is using of property variety in air and fuel mixture with using technologies like Variable Valve Timing (VVT) system.
    The purpose of this work is development a simple model in basis physics of 3 zone, homogeneous, ignition combustion with a partial kinetics model that this model can predict the knock phenomenon onset with good precision for various qualities of mixture. This study survey effect of air and fuel mixture property on knock onset in ignition internal combustion chamber by combined a 3 zones, homogeneous combustion model and detail chemical kinetics. Therefore, a developed 3 zones model associated with a detail mechanism of iso-octhane include 409 reaction and 84 chemical species and applied on unburned zone for anticipate knock onset. The main idea in this study was independent solving equations and using temperature, pressure and unburned mixture composition prediction as kinetics model input in each time step. At the end, effect of various parameters had measured like pressure and temperature of input mixture, compression ratio, equivalence ratio, engine speed, ignition time, valve timing, and residual gas percent. Also effect of using recirculates exhaust gases on knock had surveyed. The simulation results had validated with experimental results that obtain from Pride engine M13-Euro4 tests and Ricardo engine test in MIT university. These results had well similarity.
  9. Keywords:
  10. Stamping ; Chemical Kinetic ; Iso-Octone ; Spark Ignition Engines ; Valve Timing ; Residual Gases

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