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Title: Investigation into the performance of an internal combustion engine under transient operating conditions
Author: Jabbar, A. A. R. A.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1981
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This thesis examines the way in which the engine torque is affected during transient operation associated with rapid changes in throttle position. These operations are very much in evidence during city and urban driving where the engine operates mainly in a transient state. Rapid changes in throttle position tend to affect the mixture flow inside the inlet manifold and hence engine torque is affected. Theoretical and experimental investigations were carried out on transient conditions relating to rapid opening of the throttle from the engine idling position. Theoretical analysis carried out looked at the manner in which such rapid change in throttle movement affected the conditions inside the inlet manifold (i.e. manifold pressure, air velocity, air/fuel ratio, and the mixture flow of fuel droplet inside the inlet duct). The experimental work was carried out on an 1100 c.c. Ford Escort engine driving an inertia flywheel in order to simulate the transient loads. No acceleration pump was fitted to the engine's carburettor. The experimental results confirmed the theoretical prediction indicating the manner in which the conditions inside the inlet manifold (i.e. inlet manifold pressure, air velocity) changed immediately after rapid opening of the throttle. The resultant effect of these changing conditions on the instantaneous engine torque was an initial torque increase, followed by a progressive decrease, before the torque recovered to the normal values. This variation in torque is attributed to the changes in air/fuel ratio occurring in the flow mixture inside the inlet manifold. This period of decreasing torque due to weakening mixture is normally eliminated by the accelerating charge normally injected from an acceleration pump fitted to the carburettor. This detailed analysis of both inlet conditions and torque during transient operation may be used in order to match the requirements of the engine under such transient operation, which is essential from an economy point of view.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available