Swirl and Tumble Control in Direct Injection Engines using Synthetic Jet Actuators
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Date
2016-05
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The Ohio State University
Abstract
In a direct injection engine, fuel injected directly into the combustion chamber mixes with air entering the intake port to form a combustible mixture. Some direct injection engines attempt to optimize this air-fuel mixture near the source of ignition using a movable valve in the intake port which creates swirl and tumble to transport the mixture in a desired direction. However, this valve presents an obstruction to airflow and only provides limited control of the swirl and tumble of air entering the combustion chamber. It was hypothesized that replacing the valve with an array of synthetic jet actuators would remove the physical obstruction in the intake port and allow for greater control of moving air inside the combustion chamber. Synthetic jet actuators contain a chamber, an orifice, and a diaphragm which oscillates at a controlled frequency. The performance of these actuators depends on their dimensions. In this project, the dimensions of the actuator had to be limited to fit on an intake pipe which required them to be smaller than those in other studies. A lumped parameter model was implemented in order to find actuator dimensions which would perform adequately. An actuator was created at these dimensions and tested to determine jet velocities at varying frequencies. Four diaphragms were created to test with the actuator. The diaphragms performed sufficiently producing jet velocities up to 78.05 m/s, however other diaphragms performed insufficiently with maximum jet velocities less than 10 m/s. These findings indicate that a synthetic jet actuator of sufficient size can be created, but more research must be done on creating sufficient diaphragms. The analysis of the small scale synthetic jet actuators used in this study can also find use in many aeronautical applications.
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Keywords
Swirl and Tumble Control, Synthetic Jet Actuators, Direct Injection Engines, Flow Control, Actuators, Synthetic Jets