Fluid structure interaction in a rocket nozzle

Abstract: This thesis is carried out at Volvo Aero in Trollhättan at the Department
of combustion chambers and nozzles. The aim is to compare two methods for
coupled analysis between structural and fluid calculations and assess if
the methods can be applied on a whole nozzle. The softwares used are ANSYS
CFX and ANSYS mechanical. The two methods evaluated are unidirectional and
bidirectional Fluid Structure Interaction (FSI). The calculations are made
on a section of half a coolant channel and the flow of the coolant, heat
transfer and the displacements are calculated for the first three seconds
of a start-up. In unidirectional FSI the calculations in ANSYS CFX are made
first, the convection and pressure at the walls of the channel obtained are
then exported to ANSYS mechanical where the displacements are calculated.
In bidirectional FSI the calculations are performed simultaneously. The
heat flux and total force density are calculated in ANSYS CFX while the
temperature and displacement are calculated in ANSYS Mechanical. The
conclusion of the thesis is that due to long calculation times neither of
the methods is applicable on a whole nozzle even though unidirectional FSI
is about ten times faster than bidirectional FSI for the case studied.