Non-radial fiber turbine performance for low pressure turbine via Cfd and experimental (cold flow) / Siti Nor Syazwani Ridzuan

This thesis presents the evaluation of non-radial fiber turbine. The turbine adapted to
an electrical turbo comporting (ETC) for recovering waste energy in the internal
combustion engine. The ETC was designed to produce 1KW of power, rotate at 50000
rpm and expand the pressure ratio of 1.1. The pressure ratio for the off-design
operations was limited between 1.05 and 1.25. The turbine cannot operate higher than
1.25 due to choking problem. Limitation of the current design caused the operation of
the LPT to produce chocked flow at certain mass flow rate and the efficiency
significant dropped when the turbine was operated at pressure ratio 1.25. The flow
field of the non-radial fiber turbine (NRFT) was studied by adjusting the exit
camberlines which were lean backward swept and forward swept from the base design
of non-radial fiber element. The data were collected through numerical and
experimental analyses by using cold flow testing facility. The low pressure turbine
(LPT) analysis was done by using computational fluid dynamic (CFD) simulation for
single passage. The three dimensional turbulence fluid flow motion is described by
using the Reynolds-Averaged Navier-Stokes equations (RANS) in the CFD
modelling. The k- turbulence model is used in this study to model the Reynolds
stresses. The result for the numerical analysis was compared with the baseline design
by analysing the performance of efficiency and swallow capacity of the LPT. The
flow field analysis is discussed in order to investigate the entropy generated at
different exit angles. According to the validation data that have been done using CFD
baseline with the experimental it is shown that the efficiency data for the velocity ratio
under 0.7 with Relative standard deviation of 0.37. The turbine performances for the
backswept design has showed an increment of 2% for the total-to-static efficiency and
higher swallow capacity at the PR=1.25. This shows that the backswept design has a
better design than the baseline and forward swept design. Base on the current
outcomes the backswept have shown the highest efficiency 0.787 at PR 1.05-1.11 but
increased in entropy generated due to increase of the temperature and decreased of
pressure at the outlet as it approaching the higher mass flow rate. The flow field
analysis study shows at the mid-section of the blade which is 0.5 of the wise-span the
flow were chocking as the flow intake for the backswept are higher compared to
forward swept once it passes through the mid place the exit flow not constant and
make the velocity curl are reduces that lead to entropy increased.