CFD Simulation of Air Movement Inside the Cylinder of an Internal Combustion

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CFD SIMULATION OF AIR MOVEMENT INSIDE THE CYLINDER OF AN INTERNAL
COMBUSTION
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LITERATURE REVIEW
The engines and piston design
The engines and piston uses small skirts since they grow shorter and lighter with
evolution. Currently, pistons are built from aluminium alloys as opposed to silicon that
lowers thermal expansion and improves resistance (Guzzella & Onder, 2009). The
introduction of piston “tops” with bowl like tops that is subjected to the combustion chamber
giving it different effects in the heating process. Primarily the piston crown act as the burning
chamber since the diesel has no ignition phase. This improves the combustion ratio. Gasoline
engines have employed the use of advanced crowned pistons. The fuel and air motion are
managed by the pistons bowl design during compression stroke before ignition (Stone, 2009)
Bowl shaped piston design creates perfect turbulence mixture of air and fuel for
efficient combustion generating more power for the engine processes. Bowls are designed
with different shapes for effective fuel consumption (Chellen & Baranescu, 2010). The use of
gasoline has led to the spread of bowled pistons. The low conditions in high-speed direct
injection engines at the end of compression stoke, near top dead centre have become
critical .Air flow into the cylinder and intake valves in the induction process and its
evaluation in the compression stroke is used to determine the combustion process
(Rakopoulos & Giakoumis, 2016)
More researches and studies have been conducted on the geometry of the piston to
asses on issues affecting the flow distribution of diesel engines. The project chapter is used to
analyse previous published works that lays a foundation for more work research in this

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project. This gives a proper understanding of the research topics and gives a guide throughout
the work process. The engine cylinder flow characteristics with different pistons designs were
analysed (Ozsezen etal, 2009)
Due to this, the intake and compression stroke analysis have been undertaken at
realistic operating conditions and proper turbulence and velocity flows generated in every
combustion chamber verified in details (Taylor, 2009). Analysis shows that the geometry of
the piston had a small effect on in-cylinder flow at the beginning of the compression stroke
and the intake stroke. The bowl shaped piston is of great importance at the TDC and at the
start of the expansion stroke as it regulates the turbulence velocity fields and ensemble-
average mean (Rakopoulos etal, 2017)
The turbulence or swirl motion of the engine cylinder during the compression and
intake strokes of the pistons geometry construction with a single intake valve had been
analysed and studied (Som & Datta, 2018), though a small validation presentation has been of
the analysis and calculation made. Full calculation of the analysis and solutions of the
compression and intake processes have been conducted and analysed by Chen et al who
presented the calculations and compared the performance of the engine with experimental
results obtained from conducted analysis (Rakopoulos etal, 2011)
From the data has been used to indicate that the calculated results were used to predict
the turbulence velocity flow. Comparisons of the results with the real geometry were used to
explain the error differences in the experimental data and the disadvantages of the standard
k–ɛ model. In addition to that, Dillies et al conducted a study and too presented the same
calculation analysis of a diesel engine having a single intake valve for a single combustion
chamber, the case which data was correctly merging well with the conducted experimental

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results. A computational review cited on large eddy simulation was done (Benjumea &
Agudelo, 2009)
Computational fluid dynamics
The computational fluid dynamics analysis applies an integration of computational
software, mathematical modelling and numerical methods in order to visualize and give a
prediction of both the quantitative and the qualitative characteristics of fluid flows (Anderson
& Wendt, 2015 )(Niu etal, 2010). This tool has the capability of providing various solutions
such as the multi-phase and single phase conditions isothermal flow, a chemical reaction in
fluid flow as well as the incompressible or compressible fluid flow (Chung, 2010).
In our daily experiences, we experience various circumstances involving fluid flow
and the computational fluid dynamics analysis tool has been applied while performing the
analysis of the air conditioning, engine combustion, ventilation as well as the propulsion
system (Versteeg & Malalasekera, 2009). For the internal combustion, there exist four
methodologies which differ from one another with regards to the results of the operators.
These methods include
 In-cylinder combustion simulation (Kollmann, 2012)
 Port flow analysis (Sayma, 2009)
 Full cycle simulation (Roache, 2011)
 Cold flow analysis (Hu, 2012)
Port flow analysis
In this method, depending on the selection of the operator, the engine configuration is
held frozen at a certain engine cycle angle. This technique is very significant and is very