Scholarly record
APPLICATION OF A PHYSICAL MODEL FOR DETERMINING THE CRANKSHAFT RUN-UP TIME OF AN ENGINE AS AN INITIAL STEP IN ENGINE MAPPING BASED ON DIMENSIONAL ANALYSIS
Abstract
The crankshaft run-up process is a critical transient phase in internal combustion engine operation, during which the engine transitions from rest or low rotational speed to a stable operating condition. This process is governed by the interaction between combustion-generated torque, mechanical resistance, and the inertia of the rotating system. Accurate modelling of this phase is important for improving engine design, reducing experimental effort, and better understanding transient engine dynamics. This paper presents a theoretical approach to modelling crankshaft run-up time using dimensional analysis based on the Buckingham Pi theorem. The method reduces a complex multi-parameter problem into a set of dimensionless groups that capture the essential physical behavior of the system. The model includes key variables such as run-up time, moment of inertia, combustion torque, fuel density, dynamic viscosity, lower heating value, droplet burning time, and vapor pressure. To simplify the analysis, several assumptions are made, including lumped-parameter representation of the crankshaft, averaged combustion torque, constant friction, neglected heat losses, and macroscopic treatment of fuel properties without detailed chemical kinetics. The physical basis of the model is the rotational form of Newton’s second law, where angular acceleration depends on the net torque acting on the system. Application of the Buckingham Pi theorem yields five independent dimensionless groups describing relationships between fuel properties, combustion characteristics, and mechanical response. The final model expresses run-up time as a function of the inertia-to-torque ratio and a dimensionless function of these similarity parameters.
Publication details
References5
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