<p>Two-stroke, opposed
piston engines have gained recent attention for their improved thermal
efficiency relative to the conventional inline or V-configuration. One advantage of two-stroke, opposed piston
engines is a reduction in heat losses since there is no cylinder head. Another advantage is improved gas exchange
via uniflow scavenging since the exhaust and intake ports may be located near
bottom dead center of the exhaust and intake pistons, respectively. One challenge with the design of two-stroke
engines is promoting turbulence within the cylinder. Turbulence is important for mixing air and
fuel in the cylinder and for increasing flame speed during combustion. </p>
<p>This work investigates
the flow and turbulence through two-stroke, opposed piston engines using
computational fluid dynamics (CFD). Specifically,
the role of intake manifold and intake port geometry on turbulence within the
cylinder was investigated by systematically modifying the engine geometry. Turbulence was then quantified using three
metrics: circulation around the cylinder axis (swirl), circulation normal to
the cylinder axis (tumble), and volume average turbulent kinetic energy (TKE)
within the cylinder.</p>
Increasing the swirl angle from 0 degrees to 10 degrees
increased the in-cylinder swirl by a factor of 3. Increasing the swirl angle also increased the
volume average TKE by a range of 7.6% to 36.5% across the three cylinders of
the engine. A reverse tilt angle of 15 degrees
increased tumble circulation near the piston face but decreased tumble
circulation by a factor of 3 near the center of the cylinder. The next step for research on this would be
to apply more geometric manipulations to the manifold of the swirl engine
design to balance the mass flow rate for each port. Following the redesign of the manifold the
next step is to perform a dynamic CFD test to verify the mass flow has been
balanced under a dynamic scenario.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/17159408 |
| Date | 18 December 2021 |
| Creators | James C Rieser (11818853) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/MANIFOLD_AND_PORT_DESIGN_FOR_BALANCED_FLOW_AND_INCREASED_TURBULENCE_IN_A_TWO-STROKE_OPPOSED_PISTON_ENGINE/17159408 |
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