Project Report on CFD Measurements of the Cooling Air in a DC-Motor

 Abstract
        The cooling system of a DC-motor is examined in this thesis. A change of direction of the
cooling air is desired to prevent the generated coal dust from entering into the windings of the
machine. Ultimately this will have a negative effect on the cooling in the machine and the loss
of cooling needs to be compensated through other ways. The purpose of this thesis is to work
for an improved operational safety and performance of the DC-motor and to make it more
competitive in the market. By modelling the interior geometry of the machine and defining
the boundaries in the software programs Gambit and FLUENT respectively, the motion and
the heat transfer of the airflow could be simulated. The simulation results would give us an
understanding of the flow pattern which later could be used to develop design modifications
on the cooling system of a DC-motor. In this thesis the main focus lies on creating a
simulation model with a sufficiently fine mesh size.

Introduction
       In general it can be said that all electrical equipments has a production of heat due to the
electrical losses in the system. This heat is increasing the temperature of the surrounding
materials and it can damage some sensitive parts of the unit. To insure a secure operation the
temperature needs to be kept down by leading the heat away, either naturally or by a special
design.
In electrical rotating machines electrical power is used to create mechanical power through
electromagnetic forces. The mechanical and electrical power losses in the system are
transformed into heat and to avoid overheating some kind of cooling system is needed. An
effective way to cool down the motor is to lead a fluid, either water or air, to flow over the hot
parts of the machine and transfer the heat out of the system.
A highly efficient machine is a machine that for a minimum material cost can generate a high
level of mechanical power output. This means that for a certain machine a maximum of
mechanical power output is desired. When increasing the power for the motor you need to
deal with the additional heat generated from this. Therefore the cooling plays a key role in the
improvement of the machine.


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