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Investigation of Losses Prediction Methods in 1D for Axial Gas Turbines

Dahlquist N, Adrian (2009)
Department of Energy Sciences
Abstract
A brief description of the physical flow phenomena in a blade row that creates losses
in an axial gas turbine and correlations to estimate these losses in a mean line
calculation are given. Investigation and comparison of the loss correlations for 1D
mean line calculation between the in-house program (CTC) used at Siemens and loss
correlations present in the open literature were made. The investigation is primarily
focused on the problems associated with modeling off-design effects on profile and
secondary losses, and the effect of tip leakage losses at all loads. For the off-design
condition both positive and negative flow incidence were covered with internal tests
and numerical 2D investigations. The increase in blade losses at... (More)
A brief description of the physical flow phenomena in a blade row that creates losses
in an axial gas turbine and correlations to estimate these losses in a mean line
calculation are given. Investigation and comparison of the loss correlations for 1D
mean line calculation between the in-house program (CTC) used at Siemens and loss
correlations present in the open literature were made. The investigation is primarily
focused on the problems associated with modeling off-design effects on profile and
secondary losses, and the effect of tip leakage losses at all loads. For the off-design
condition both positive and negative flow incidence were covered with internal tests
and numerical 2D investigations. The increase in blade losses at high outlet Mach
number and how it is related to the shape of the suction surface for a blade profile was
investigated with numerical 2D simulation.
The results for the loss models are validated against previous done internal gas turbine
test runs at Siemens, external cascade tests and numerical 2D simulations.
The overall conclusions are that the in-house program (CTC) shows good prediction
ability for the off-design down to the state where the turbine reaches turn-up mode.
But some questions about CTC’s distribution between profile and secondary losses
are discussed.
For the tip leakage loss it was highlighted that CTC shows a somewhat low loss for a
constant clearance and also a rather low increase with relative clearance change. A
limitation in the prediction ability because the absence of some believed important
parameter was also seen and an alternative model was suggested for unshrouded
blades.
It is clear that there for most blade designs is seen a sudden increase in the blade
losses at an outlet Mach number in the region of 0.9. But no obvious relations to
which blade parameters that determine the absolute increase were found (Less)
Please use this url to cite or link to this publication:
author
Dahlquist N, Adrian
supervisor
organization
year
type
H1 - Master's Degree (One Year)
subject
keywords
Loss models, axial gas turbines
language
English
id
1423748
date added to LUP
2009-06-23 10:38:56
date last changed
2009-06-23 10:38:56
@misc{1423748,
  abstract     = {A brief description of the physical flow phenomena in a blade row that creates losses
in an axial gas turbine and correlations to estimate these losses in a mean line
calculation are given. Investigation and comparison of the loss correlations for 1D
mean line calculation between the in-house program (CTC) used at Siemens and loss
correlations present in the open literature were made. The investigation is primarily
focused on the problems associated with modeling off-design effects on profile and
secondary losses, and the effect of tip leakage losses at all loads. For the off-design
condition both positive and negative flow incidence were covered with internal tests
and numerical 2D investigations. The increase in blade losses at high outlet Mach
number and how it is related to the shape of the suction surface for a blade profile was
investigated with numerical 2D simulation.
The results for the loss models are validated against previous done internal gas turbine
test runs at Siemens, external cascade tests and numerical 2D simulations.
The overall conclusions are that the in-house program (CTC) shows good prediction
ability for the off-design down to the state where the turbine reaches turn-up mode.
But some questions about CTC’s distribution between profile and secondary losses
are discussed.
For the tip leakage loss it was highlighted that CTC shows a somewhat low loss for a
constant clearance and also a rather low increase with relative clearance change. A
limitation in the prediction ability because the absence of some believed important
parameter was also seen and an alternative model was suggested for unshrouded
blades.
It is clear that there for most blade designs is seen a sudden increase in the blade
losses at an outlet Mach number in the region of 0.9. But no obvious relations to
which blade parameters that determine the absolute increase were found},
  author       = {Dahlquist N, Adrian},
  keyword      = {Loss models,axial gas turbines},
  language     = {eng},
  note         = {Student Paper},
  title        = {Investigation of Losses Prediction Methods in 1D for Axial Gas Turbines},
  year         = {2009},
}