A Time Domain Analytical Approach to Predict the Primary Intake Runner Dynamics of a Single Cylinder Engine PDF Download

Author: Shankar Kumar
Publisher:
ISBN:
Category : Internal combustion engines
Languages : en
Pages : 216

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Book Description
Abstract: The wave dynamics in the intake system of internal combustion engines plays an important role in determining the engine performance characterized by the volumetric efficiency and torque. Numerous studies have been carried out to understand the nature of the wave action by investigating the pressure and velocity fluctuations in the intake system and their influence on engine performance. The complexities involved with the presence of multiple cylinders and plenums, have promoted the use of single cylinder (SC) engines as a simpler tool to measure and predict the behavior of acoustic waves in the intake system. Even with the SC engines, the acoustic phenomenon is complicated by factors such as the geometry of the intake port and runner, the intake valve lift profile, the pulsating fluid flow due to the piston motion, the backflow of fresh charge/exhaust gases into the intake duct, and the complex nature of the viscous and separation losses. Typically, the pressure fluctuations are studied computationally by solving the NavierStokes equations and validated experimentally. Pure analytical techniques to predict the dynamics of the intake system are rare, and can be grouped as time- and frequencydomain based methods. Both methods available in the literature rely heavily on the experimental data and are restricted to rather narrow engine geometry and operating conditions. The present work is aimed at studying the acoustic characteristics of the induction system of a Ford SC research engine. A time-domain based analytical formulation has been developed to estimate the pressure field in the intake system. The objective is to capture the effect of time-varying piston and valve motion on the acoustics of the induction system. These results have been compared with the experimental data and the numerical predictions (performed using Ford Motor company's engine simulation code MANDY), to identify the applicability as well as the potential limitations of the analytical model. The analytical pressure predictions have subsequently been used to calculate the acoustic velocities in the intake duct, hence the volumetric efficiency at various engine speeds. The mathematical technique developed in the present work is expected to be useful because of its simplicity and the insights it could offer into the understanding of the physical processes.