Experimental and Numerical Study of Swirling ... - Solid Mechanics
Experimental and Numerical Study of Swirling ... - Solid Mechanics
Experimental and Numerical Study of Swirling ... - Solid Mechanics
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<strong>Experimental</strong> <strong>and</strong> <strong>Numerical</strong> <strong>Study</strong> <strong>of</strong> <strong>Swirling</strong> Flow in Scavenging Process for 2-Stroke<br />
Marine Diesel Engines<br />
Summary & Conclusions<br />
The aim <strong>of</strong> this thesis was to study <strong>and</strong> underst<strong>and</strong> various aspects <strong>of</strong> the<br />
confined swirling flow during the uniflow scavenging processes for large<br />
two-stroke marine diesel engines. A description <strong>of</strong> the working <strong>of</strong> large two<br />
stroke marine diesel engines were given in order to underst<strong>and</strong> the role <strong>of</strong><br />
scavenging process <strong>and</strong> its significance on the overall engine performance<br />
<strong>and</strong> efficiency. Different features <strong>of</strong> uniflow scavenging process in currently<br />
operational marine diesel engines were discussed <strong>and</strong> it was identified that<br />
the real engine scavenging process is very complex, scientifically less<br />
understood in detail <strong>and</strong> one <strong>of</strong> the potential processes for making<br />
improvements in order to develop future fuel <strong>and</strong> environmentally efficient<br />
marine diesel engines.<br />
Out <strong>of</strong> the many aspects <strong>of</strong> complex physics <strong>of</strong> scavenging process, the focus<br />
in this thesis was to study <strong>and</strong> characterize the confined swirling flow during<br />
the scavenging process. The study was conducted by developing a simplified<br />
experimental model with air at room temperature <strong>and</strong> pressure without<br />
considering mixing <strong>and</strong> stratification. The model comprised <strong>of</strong> a transparent<br />
acrylic cylinder fitted to a swirl generator having guide vanes. Features like a<br />
movable piston <strong>and</strong> changing cylinder length were also included. The design<br />
is more close to features <strong>of</strong> engine cylinder <strong>and</strong> makes it different from the<br />
confined swirling pipe flow experimental setups earlier reported in scientific<br />
literature. Different experimental techniques were used <strong>and</strong> CFD simulations<br />
were performed <strong>and</strong> the results were compared with the experimental data.<br />
1.1 <strong>Experimental</strong> Measurements<br />
Two different experiments are conducted using Stereoscopic PIV<br />
measurements at different cross-sectional planes. For both the experiments<br />
the measurements are conducted at fixed guide vane angle <strong>of</strong> the swirl<br />
generator <strong>and</strong> two Reynolds numbers in the cylinder i.e. 65,000 <strong>and</strong> 32,500.<br />
For each measurement, nearly 1000 instantaneous PIV snapshots were taken.<br />
For the fully open intake port, LDA measurements are also conducted in the<br />
inlet section <strong>and</strong> also at the entrance <strong>of</strong> the cylinder. The design swirl<br />
parameter for the experimental setup is found to be 0.34 <strong>and</strong> is kept constant<br />
for all the measurements.<br />
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Summary & Conclusions