In this paper, a method to influence the vibratory blade stresses of mixed flow turbocharger turbine blade by varying the local blade thickness in spanwise direction is presented. Such variations have an influence on both the static and the vibratory stresses and therefore can be used for optimizing components with respect to high-cycle fatigue (HCF) tolerance. Two typical cyclic loadings that are of concern to turbocharger manufacturers have been taken into account. These loadings arise from the centrifugal forces and from blade vibrations. The objective of optimization in this study is to minimize combined effects of centrifugal and vibratory stresses on turbine blade HCF and moment of inertia. Here, the conventional turbine blade design with trapezoidal thickness profile is taken as baseline design. The thicknesses are varied at four spanwise equally spaced planes and three streamwise planes to observe their effects on static and vibratory stresses. The summation of both the stresses is referred to as combined stress. In order to ensure comparability among the studied design variants, a generic and constant excitation order-dependent pressure field is used at a specific location on blade. The results show that the locations of static and vibratory stresses, and hence the magnitude of the combined stresses, can be influenced by varying the blade thicknesses while maintaining the same eigenfrequencies. By shifting the maximum vibratory stresses farther away from the maximum static stresses, the combined stresses can be reduced considerably, which leads to improved HCF tolerance.

References

References
1.
Rodgers
,
C.
,
1968
, “
Paper 5: A Cycle Analysis Technique for Small Gas Turbines
,”
Proc. Inst. Mech. Eng., Conf. Proc.
,
183
(
14
), pp.
37
49
.
2.
Chou
,
C.-C.
, and
Gibbs
,
C. A.
,
1989
, “
The Design and Testing of a Mixed-Flow Turbine for Turbochargers
,”
SAE
Paper No. 890644.
3.
Abidat
,
M.
,
1991
, “
Design and Testing of a Highly Loaded Mixed Flow Turbine
,” Ph.D thesis, University of London, London.
4.
Khairuddin
,
U.
,
Costall
,
A. W.
, and
Martinez-Botas
,
R. F.
,
2015
, “
Influence of Geometrical Parameters on Aerodynamic Optimization of a Mixed-Flow Turbocharger Turbine
,”
ASME
Paper No. GT2015-42053
.
5.
Mueller
,
L.
,
Alsalihi
,
Z.
, and
Verstraete
,
T.
,
2012
, “
Multidisciplinary Optimization of a Turbocharger Radial Turbine
,”
ASME J. Turbomach.
,
135
(
2
), p.
021022
.
6.
Smith
,
W.
, and
Wilkins
,
C. S. B.
,
2016
, “
An Improved Approach to HCF Development for Vaneless Turbine Stages
,” iMechE Paper No. C6231-164.
7.
Klaus
,
M.
,
2007
, “
Strömungsinduzierte Schaufelschwingungen in Radialturbinen Mit Beschaufeltem Spiralgehäuse
,” Ph.D. thesis, Universität Karlsruhe (TH), Karlsruhe, Germany.
8.
Farin
,
G.
,
2014
,
Curves and Surfaces for Computer-Aided Geometric Design: A Practical Guide
,
Elsevier Science
,
Boston, MA
.
9.
Drozdowski
,
R.
,
2011
, “
Berechnung Der Schwingbeanspruchungen in Radialturbinenrädern Unter Berücksichtigung Realer Bauteilgeometrien
,” Ph.D. thesis, TU Dresden, Dresden, Germany.
10.
Wilson
,
A. U. T.
,
1993
, “
Turbine Blade Dynamics and Blade-Vane Interaction in a Radial Inflow Turbine
,”
AGARD Conference Proceedings AGARD CP
, Vol.
537
, pp.
35–1
35–11
.
11.
Myhre
,
M.
,
2003
, “
Numerical Investigation of the Sensitivity of Forced Response Characteristics of Bladed Disks to Mistuning
,” Ph.D. thesis, KTH, Energy Technology, Stockholm, Sweden.
12.
Piersol
,
A.
, and
Paez
,
T.
,
2009
,
Harris' Shock and Vibration Handbook
,
McGraw-Hill handbooks, McGraw-Hill Education
, New York.
13.
Dynardo GmbH
,
2016
, “
Methods for Multi-Disciplinary Optimization and Robustness Analysis
,”
Dynardo GmbH User Manual
, Dynardo GmbH, Weimar, Germany.
You do not currently have access to this content.