Multi-Disciplinary Design Optimisation of the Cooled Squealer Tip for High Pressure Turbines

The turbine tip geometry can significantly alter the performance of the turbine stage; its design represents a challenge for a variety of reasons. Multiple disciplines are involved in its design and their requirements limit the creativity of the designer. Multi-Disciplinary Design Optimisation (MDO) offers the capability to improve the performance whilst satisfying all the design constraints. This paper presents a novel design of a turbine tip achieved via MDO techniques. A fully parametrised Computer-Aided Design (CAD) model of the turbine rotor is used to create the squealer geometry and to control the location of the cooling and dust holes. A Conjugate Heat Transfer Computational Fluid Dynamics (CFD) analysis is performed for evaluating the aerothermal performance of the component and the temperature the turbine operates at. A Finite Element (FE) analysis is then performed to find the stress level that the turbine has to withstand. A bi-objective optimisation reduces simultaneously the aerodynamic loss and the stress level. The Multipoint Approximation Method (MAM) recently enhanced for multi-objective problems is chosen to solve this optimisation problem. The paper presents its logic in detail. The novel geometry offers a significant improvement in the aerodynamic performance whilst reducing the maximum stress. The flow associated with the new geometry is analysed in detail to understand the source of the improvement.

[1]  P. Adami,et al.  Analysis of Radial Migration of Hot-Streak in Swirling Flow Through High-Pressure Turbine Stage , 2013 .

[2]  J. Denton.  Loss Mechanisms in Turbomachines , 1993 .

[3]  Joaquim R. R. A. Martins,et al.  Multidisciplinary design optimization: A survey of architectures , 2013 .

[4]  Neil William Harvey,et al.  A Computational Study of a Novel Turbine Rotor Partial Shroud , 2000 .

[5]  P. Adami,et al.  Analysis of Radial Migration of Hot-Streak in Swirling Flow Through HP Turbine Stage , 2012 .

[6]  Shahrokh Shahpar,et al.  Multi-Disciplinary Analyses for the Design of a High Pressure Turbine Blade Tip , 2016 .

[7]  Howard P. Hodson,et al.  Aeromechanical Optimisation of a Winglet-Squealer Tip for an Axial Turbine , 2010 .

[8]  P. Lancaster,et al.  Surfaces generated by moving least squares methods , 1981 .

[9]  Vassili Toropov,et al.  NEW DEVELOPMENTS IN STRUCTURAL OPTIMIZATION USING ADAPTIVE MESH REFINEMENT AND MULTIPOINT APPROXIMATIONS , 1997 .

[10]  Howard P. Hodson,et al.  High Efficiency Cavity Winglets for High Pressure Turbines , 2014 .

[11]  Vassili Toropov,et al.  Multiparameter structural optimization using FEM and multipoint explicit approximations , 1993 .

[12]  William N. Dawes,et al.  Using Level Sets as the Basis for a Scalable, Parallel Geometry Engine and Mesh Generation System (Invited) , 2009 .

[13]  Howard P. Hodson,et al.  Winglets for Improved Aerothermal Performance of High Pressure Turbines , 2013 .

[14]  Vassili Toropov,et al.  Simulation approach to structural optimization , 1989 .

[15]  Jaroslaw Szwedowicz,et al.  Effect of Various Tip Clearance Squealer Design on Turbine Stage Efficiency , 2015 .

[16]  Shahrokh Shahpar,et al.  Investigation Into Coupling Techniques for a High Pressure Turbine Blade Tip , 2015 .

[17]  Roger W. Ainsworth,et al.  Turbine Aerodynamic Performance Measurement Under Nonadiabatic Conditions , 2012 .

[18]  William N. Dawes,et al.  Application of Topology-Free Optimization to Manage Cooled Turbine Tip Heat Load , 2009 .

[19]  John D. Denton,et al.  The 1993 IGTI Scholar Lecture: Loss Mechanisms in Turbomachines , 1993 .

[20]  Howard P. Hodson,et al.  Aeromechanical Optimization of a Winglet-Squealer Tip for an Axial Turbine , 2014 .

[21]  Ali Ameri,et al.  Effect of Squealer Tip on Rotor Heat Transfer and Efficiency , 1997 .

[22]  John D. Coull,et al.  The Influence of Boundary Conditions on Tip Leakage Flow , 2015 .

[23]  N. Olhoff.  Multicriterion structural optimization via bound formulation and mathematical programming , 1989 .

[24]  Moinier,et al.  Preconditioned Euler and Navier-Stokes Calculations on Unstructured Meshes , 1998 .

[25]  Shahrokh Shahpar,et al.  Numerical investigations of different tip designs for shroudless turbine blades , 2015 .

[26]  Vassili Toropov,et al.  Mid-range metamodel assembly building based on linear regression for large scale optimization problems , 2012 .

[27]  William N. Dawes,et al.  Practical and reliable mesh generation for complex, real-world geometries , 2014 .

[28]  Eric Warren Curtis,et al.  The Effect of Clearance on Shrouded and Unshrouded Turbines at Two Levels of Reaction , 2010 .