Methods and Tools for Multidisciplinary Optimization of Axial Turbine Stages With Relatively Long Blades

2004 ◽  
Author(s):  
Leonid Moroz ◽  
Yuri Govoruschenko ◽  
Leonid Romanenko ◽  
Petr Pagur
Keyword(s):  
Optimal Design ◽  
Turbine Blades ◽  
Multidisciplinary Optimization ◽  
Stress Strain ◽  
Axial Turbine ◽  
Maximal Efficiency ◽  
Vibration Reliability ◽  
Technological Limitations

An effective methodology for optimal design of axial turbine blades is presented. It has been used for achieving stage maximal efficiency meeting both stress-strain and vibration reliability requirements and taking into account technological limitations.

Optimization of Supersonic Axial Turbine Blades Based on Surrogate Models

2020 ◽  
Author(s):  
Markus Waesker ◽  
Bjoern Buelten ◽  
Norman Kienzle ◽  
Christian Doetsch
Keyword(s):  
Reynolds Number ◽  
Turbine Blade ◽  
Surrogate Model ◽  
Cfd Simulation ◽  
Turbine Blades ◽  
Energy System ◽  
Design Parameters ◽  
Blade Design ◽  
Axial Turbine ◽  
Velocity Coefficient

Abstract Due to the transition of the energy system to more decentralized sector-coupled technologies, the demand on small, highly efficient and compact turbines is steadily growing. Therefore, supersonic impulse turbines have been subject of academic research for many years because of their compact and low-cost conditions. However, specific loss models for this type of turbine are still missing. In this paper, a CFD-simulation-based surrogate model for the velocity coefficient, unique incidence as well as outflow deviation of the blade, is introduced. This surrogate model forms the basis for an exemplary efficiency optimization of the “Colclough cascade”. In a first step, an automatic and robust blade design methodology for constant-channel blades based on the supersonic turbine blade design of Stratford and Sansome is shown. The blade flow is fully described by seven geometrical and three aerodynamic design parameters. After that, an automated numerical flow simulation (CFD) workflow for supersonic turbine blades is developed. The validation of the CFD setup with a published supersonic axial turbine blade (Colclough design) shows a high consistency in the shock waves, separation zones and boundary layers as well as velocity coefficients. A design of experiments (DOE) with latin hypercube sampling and 1300 sample points is calculated. This CFD data forms the basis for a highly accurate surrogate model of supersonic turbine blade flow suitable for Mach numbers between 1.1 and 1.6. The throat-based Reynolds number is varied between 1*104 and 4*105. Additionally, an optimization is introduced, based on the surrogate model for the Reynolds number and Mach number of Colclough and no degree of reaction (equal inlet and outlet static pressure). The velocity coefficient is improved by up to 3 %.

Improvement of Aerodynamic and Strength Characteristics of a Multi-Shaft Axial Turbine of a Turboshaft Engine

2021 ◽  
Author(s):  
Grigorii Popov ◽  
Evgenii Goriachkin ◽  
Igor Egorov ◽  
Oleg Baturin ◽  
Anton Salnikov ◽  
...  
Keyword(s):  
Mutual Influence ◽  
Multidisciplinary Optimization ◽  
Structural Constraints ◽  
Complex Task ◽  
Axial Turbine ◽  
Strength Factor ◽  
Rotor Wheel ◽  
Safety Margins ◽  
Deformation Processes ◽  
Turboshaft Engine

Abstract The article presents the results of solving the complex task of increasing the rotor wheel strength factor and the efficiency of the twin-shaft axial turbine of the small turboshaft engine using methods of multidisciplinary optimization. This turbine consists of a single-stage compressor turbine (CT) and a free turbine (FT). An analysis of the original variant of the turbine revealed that the strength factor of their rotor wheels are significantly lower than the necessary structural requirement. To eliminate the occurring problem at the first step the initial task of estimation the rotor wheels only on the basis of structural requirements was performed without taking into account aerodynamic processes. As a result, variants of the turbine rotor wheels were obtained to provide the structural constraints. They were used as starting points for the complex task of optimization, taking into account aerodynamic and deformation processes. The task of multi-disciplinary CT and FT optimization was solved step by step. As a first step, specific CT and FT models were built, which as a result of their optimization allowed to ensure acceptable strength factor of rotor wheel and slightly increased turbine efficiency. In the next step, a joint model of both turbines was built and tested. Its analysis showed that mutual influence of these working processes of the turbines leads to a distortion of the flow temperature distribution in the flow path, which causes a reduction of the FT blades strength criteria to an unacceptable level. Further optimization of the joint turbine model, taking into account aerodynamic and deformation processes, made it possible to increase the efficiency of both turbines by 0.4% (for each one), providing the necessary safety margins for the disks.

Experimental Validation of Forced Response Methods in a Multi-Stage Axial Turbine

2018 ◽  
Author(s):  
Thomas Hauptmann ◽  
Christopher E. Meinzer ◽  
Joerg R. Seume
Keyword(s):  
Experimental Data ◽  
Vibration Amplitude ◽  
Turbine Blades ◽  
Service Condition ◽  
Sensitivity Study ◽  
Forced Response ◽  
Tip Clearance ◽  
Computational Time ◽  
Reference Case ◽  
Axial Turbine

Depending on the in service condition of jet engines, turbine blades may have to be replaced, refurbished, or repaired in the course of an engine overhaul. Thus, significant changes of the turbine blade geometry can be introduced due to regeneration and overhaul processes. Such geometric variances can affect the aerodynamic and aeroelastic behavior of turbine blades. One goal in the development of the regeneration process is to estimate the aerodynamic excitation of turbine blades depending on these geometric variances caused during the regeneration. Therefore, this study presents an experimentally validated comparison of two methods for the prediction of forced response in a multistage axial turbine. Two unidirectional fluid structure interaction (FSI) methods, a time-linearized and a time-accurate with a subsequent linear harmonic analysis, are employed and the results validated against experimental data. The results show that the vibration amplitude of the time-linearized method is in good agreement with the experimental data and, also requires lower computational time than the time-accurate FSI. Based on this result, the time-linearized method is used to perform a sensitivity study of the tip clearance size of the last rotor blade row of the five stage axial turbine. The results show that an increasing tip clearances size causes an up to 1.35 higher vibration amplitude compared to the reference case, due to increased forcing and decreased damping work.

scholarly journals Three-dimensional optimal design of a cooled turbine considering the coolant-requirement change

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 768-778
Author(s):  
Wei Ba ◽  
Ziyuan Wang ◽  
Xuesong Li ◽  
Chunwei Gu
Keyword(s):  
Optimal Design ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Pressure Surface ◽  
Component Efficiency ◽  
Requirement Change ◽  
Cooling Air ◽  
Gas Turbine Cycle

Abstract Cooling technology is widely applied in modern turbines to protect the turbine blades, and extracting high-pressure cooling air from a compressor exerts a remarkable influence on the gas-turbine performance. However, the three-dimensional optimal design of a turbine in modern industrial practice is usually carried out by pursuing high component efficiency without considering possible changes in coolant requirement; hence, it may not exactly lead to improvement in the gas-turbine cycle efficiency. In this study, the turbine stator was twisted and leaned to achieve higher comprehensive efficiency, which is the cycle-based efficiency definition for a cooled turbine that considers both turbine aerodynamic performance and coolant requirement. First, the influence of twist and compound lean on turbine aerodynamic performance, considering stator-hub leakage, was investigated. Then, a method to predict the coolant requirement for turbines with different stator designs was applied, to evaluate coolant-requirement change at the design condition. The optimized turbines were finally compared to demonstrate the necessity of considering the coolant-requirement change in the optimal design. This indicated that proper twisting to open the throat area in the stator hub and compound lean to the pressure surface side could help improve the cooled-turbine comprehensive efficiency.

scholarly journals Shape optimization of turbine blades with the integration of aerodynamics and heat transfer

1998 ◽  
Vol 4 (1) ◽  
pp. 21-42 ◽  
Author(s):  
J. N. Rajadas ◽  
A. Chattopadhyay ◽  
N. Pagaldipti ◽  
S. Zhang
Keyword(s):  
Heat Transfer ◽  
Shape Optimization ◽  
Tangential Force ◽  
Turbine Blades ◽  
Leading Edge ◽  
Optimization Techniques ◽  
Multidisciplinary Optimization ◽  
Heat Transfer Analysis ◽  
Maximum Temperature ◽  
Force Coefficient

A multidisciplinary optimization procedure, with the integration of aerodynamic and heat transfer criteria, has been developed for the design of gas turbine blades. Two different optimization formulations have been used. In the first formulation, the maximum temperature in the blade section is chosen as the objective function to be minimized. An upper bound constraint is imposed on the blade average temperature and a lower bound constraint is imposed on the blade tangential force coefficient. In the second formulation, the blade average and maximum temperatures are chosen as objective functions. In both formulations, bounds are imposed on the velocity gradients at several points along the surface of the airfoil to eliminate leading edge velocity spikes which deteriorate aerodynamic performance. Shape optimization is performed using the blade external and coolant path geometric parameters as design variables. Aerodynamic analysis is performed using a panel code. Heat transfer analysis is performed using the finite element method. A gradient based procedure in conjunction with an approximate analysis technique is used for optimization. The results obtained using both optimization techniques are compared with a reference geometry. Both techniques yield significant improvements with the multiobjective formulation resulting in slightly superior design.

An Inverse Design Based Methodology for Rapid 3D Multi-Objective/Multidisciplinary Optimization of Axial Turbines

2011 ◽  
Author(s):  
Pietro Boselli ◽  
Mehrdad Zangeneh
Keyword(s):  
Design Method ◽  
Turbine Blades ◽  
Multidisciplinary Optimization ◽  
Inverse Design ◽  
Design Parameters ◽  
Multi Objective ◽  
Work Distribution ◽  
Blade Shape ◽  
Inverse Design Method ◽  
Axial Turbines

Design of axial turbines, especially LP turbines, poses difficult tradeoffs between requirements of aerodynamic design and structural limitations. In this paper, a methodology is proposed for 3D multi-objective design of axial turbine blades in which a 3D inverse design method is coupled with a multi-objective genetic algorithm. By parameterizing the blade using blade loading parameters, spanwise work distribution and maximum thickness, a large part of the design space can be explored with very few design parameters. Furthermore, the inverse method not only computes the blade shape but also provides accurate 3D inviscid flow information. In the simple multi-disciplinary approach proposed here the different losses in axial turbines such as endwall losses, tip leakage losses and an indication of flow separation are related through well known correlations to the blade surface velocities predicted by the inverse design method. In addition, geometrical features such as throat area, lean angles and airfoil cross sectional area are computed from the blade shape employed during the optimization. Also, centrifugal stresses and bending stresses are related to the blade geometry. The methodology is then applied to the redesign of an LP turbine rotor with the aim of reducing the maximum stresses while maintaining the performance of the rotor. The results are confirmed by using the commercial CFX CFD (Computational Fluid Dynamics) code and Ansys FEA (Finite Element Analysis) codes.

Thermo-Mechanical Fatigue of the Nickel Base Superalloy IN738LC for Gas Turbine Blades

2006 ◽  
Vol 321-323 ◽  
pp. 509-512 ◽  
Author(s):  
Jung Seob Hyun ◽  
Gee Wook Song ◽  
Young Shin Lee
Keyword(s):  
Gas Turbine ◽  
Turbine Blades ◽  
Material Behavior ◽  
Experimental Program ◽  
Nickel Base Superalloy ◽  
Strain History ◽  
Stress Strain ◽  
Mechanical Fatigue ◽  
Nickel Base ◽  
Base Superalloy

A more accurate life prediction for gas turbine blade takes into account the material behavior under the complex thermo-mechanical fatigue (TMF) cycles normally encountered in turbine operation. An experimental program has been carried out to address the thermo-mechanical fatigue life of the IN738LC nickel-base superalloy. High temperature out-of-phase and in-phase TMF experiments in strain control were performed on superalloy materials. Temperature interval of 450-850 was applied to thermo-mechanical fatigue tests. The stress-strain response and the life cycle of the material were measured during the test. The mechanisms of TMF damage is discussed based on the microstructural evolution during TMF. The plastic strain energy based life pediction models were applied to the stress-strain history effect on the thermo-mechanical fatigue lives.

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