Choice of the Pseudo-Optimal Configuration of a Cooled Gas-Turbine Blade Based on a Constrained Minimization of the Global Entropy Production Rate

1996 ◽  
Author(s):  
Gianni Natalini ◽  
Enrico Sciubba
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Entropy Generation ◽  
Optimization Procedure ◽  
Optimal Configuration ◽  
Generation Rate ◽  
Maximum Temperature ◽  
Entropy Generation Rate ◽  
Gas Turbine Blade ◽  
Blade Profile

The problem of determining the optimal configuration of a cooled gas-turbine blade is approached by an entropy minimization technique proposed in previous works by the same authors. The present paper describes the application of the same line of thought to a more complex (and realistic) pseudo-optimization procedure, in which the objective function is again the global entropy generation rate, but two integral constraints are added to the original formulation: the maximum blade temperature (weak constraint) and the overall enthalpy drop of the working fluid in the blade passage (strong constraint). The discontinuous optimization procedure is presented here in an application which resembles a trial-and-error technique, but can be rigorously and formally described and implemented [12]. As a “zero configuration”, a realistic 2-D geometry is considered, and the thermo-fluiddynamic field around it is computed via a standard finite-element code. Then, the entropy generation rates in the blade/fluid system are calculated, and the value of the overall enthalpy drop of the gas as well as the value and location of the maximum blade temperature are recorded. Keeping all other parameters fixed (in particular, maintaining the same cooling air flowrate), the geometry of the blade is slightly “perturbed”, by introducing arbitrary modifications in the blade profile, the number and location of cooling holes, etc. Again, the velocity and temperature fields are computed, and inlet conditions are tuned so that the overall enthalpy drop remains approximately constant and the blade maximum temperature does not exceed a certain assigned value. An “optimal” configuration is found, which is affected by the minimal entropy generation rate, while abiding to the imposed constraints. The procedure is demonstrated on a realistic blade profile, and is shown to produce a better performing cascade, at least in this 2-D simulation. The extension to 3-D problems is — in principle — straightforward (but see Section 3 for further comments).

An Entropic Minimization Technique for Turbine Blade Profiles

2002 ◽  
Author(s):  
Ed Walsh ◽  
Mark Davies ◽  
Roy Myose
Keyword(s):  
Boundary Layer ◽  
Velocity Distribution ◽  
Boundary Layers ◽  
Turbine Blade ◽  
Entropy Generation ◽  
Incompressible Flows ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Minimization Technique ◽  
Boundary Layer Edge

The optimization of the boundary layer edge velocity distribution may hold the key to the minimization of entropy generation in the boundary layers of turbomachinery blades. A preliminary optimization analysis in the laminar region of a non film cooled turbine blade is presented, which demonstrates the concept of how the entropy generation rate may be reduced by varying the boundary layer edge velocity distribution along the suction surface, whilst holding the work done by the blade constant. In the laminar region the analytical technique developed by Pohlhausen and others to predict the boundary layer momentum thickness in the presence of pressure gradients has been adopted to predict the entropy generated as described in other papers by the same authors. The result gives an expression for the entropy generation rate in terms of the boundary layer edge velocity distribution for incompressible flows. The boundary layer edge velocity distribution may then be represented as a polynomial with undefined variables. This allows a minimization technique to be used to minimize the entropy generation rate on these variables. Constraints are included to keep the work output constant and the diffusion low to avoid separation. In this analysis it is only the laminar region that is considered for minimization, thus it is necessary to ensure that the modified boundary layer edge velocity distribution does not undergo transition earlier than the baseline boundary layer edge velocity distribution. This is accomplished by considering transition and separation criteria available in the literature. The result of this analysis indicates that the entropy generation rate may be reduced in the laminar boundary layers by using this technique.

Turbine Blade Entropy Generation Rate: Part II — The Measured Loss

2000 ◽  
Author(s):  
F. K. O’Donnell ◽  
M. R. D. Davies
Keyword(s):  
Boundary Layer ◽  
Turbine Blade ◽  
Entropy Generation ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Local Entropy ◽  
Suction Surface ◽  
Layer Velocity ◽  
Local Entropy Generation ◽  
Profile Loss

Using detailed boundary layer velocity measurements the profile loss, expressed in terms of local entropy generation rate, is evaluated at discrete locations along the suction surface of a turbine blade in a subsonic linear cascade at a chord Reynolds number of 1.8 × 103 under adiabatic test conditions. The distribution of loss through the entire boundary layer is thus established with particular attention given to the comparison of the relative contributions from the laminar, transitional and turbulent regions. It is found that 75% of the entropy generation occurs in the laminar region of the blade, with transition being one of the key features of the overall loss distribution. Traditional correlation methods are considered and shown to give accurate results when compared to the experimental measurements within both the laminar and turbulent regions, the application of such correlations is however dependant upon knowledge of the onset and extent of transition. Finally it is demonstrated that an existing method for the evaluation of local entropy generation rate from measurements of wall shear stress in laminar flow, may be adapted for use in turbulent flow and hence the possibility is presented for the measurement of loss from surface mounted sensors.

Development of multidisciplinary optimization procedure for gas turbine blade design

1999 ◽  
Author(s):  
S. Talya ◽  
R. Jha ◽  
A. Chattopadhyay ◽  
J. Rajadas
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Optimization Procedure ◽  
Multidisciplinary Optimization ◽  
Blade Design ◽  
Gas Turbine Blade ◽  
Turbine Blade Design

Specific Entropy Generation in a Gas Turbine Power Cycle

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Y. Haseli
Keyword(s):  
Gas Turbine ◽  
Entropy Generation ◽  
Thermal Efficiency ◽  
Operating Conditions ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Minimum Entropy ◽  
Power Cycle ◽  
Specific Entropy ◽  
Energy Conversion Systems

Numerous studies have shown that the minimization of entropy generation does not always lead to an optimum performance in energy conversion systems. The equivalence between minimum entropy generation and maximum power output or maximum thermal efficiency in an irreversible power cycle occurs subject to certain design constraints. This article introduces specific entropy generation defined as the rate of total entropy generated due to the operation of a power cycle per unit flowrate of fuel. Through a detailed thermodynamic modeling of a gas turbine cycle, it is shown that the specific entropy generation correlates unconditionally with the thermal efficiency of the cycle. A design at maximum thermal efficiency is found to be identical to that at minimum specific entropy generation. The results are presented for five different fuels including methane, hydrogen, propane, methanol, and ethanol. Under identical operating conditions, the thermal efficiency is approximately the same for all five fuels. However, a power cycle that burns a fuel with a higher heating value produces a higher specific entropy generation. An emphasis is placed to distinguish between the specific entropy generation (with the unit of J/K mol fuel) and the entropy generation rate (W/K). A reduction in entropy generation rate does not necessarily lead to an increase in thermal efficiency.

Multi-Objective and Multi-Disciplinary Optimization of Gas Turbine Blade Profile and Cooling System Using Conjugate Heat Transfer Analysis

2014 ◽  
Author(s):  
Yingjie Song ◽  
Zhendong Guo ◽  
Liming Song ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Data Mining ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Conjugate Heat Transfer ◽  
Cooling System ◽  
Optimization Method ◽  
Heat Transfer Analysis ◽  
Gas Turbine Blade ◽  
Blade Profile ◽  
Multi Objective

This paper presents a multi-objective and multi-disciplinary design optimization and data mining of gas turbine blade profile and cooling system by using conjugate heat transfer analysis. A 3D multi-disciplinary aerothermal optimization and data mining is proposed and developed by integrating the global optimization method of self-adaptive multi-objective differential evolution (SMODE) algorithm based on constraint-handling method, the CHT method for aerothermal performance evaluation of gas turbine blade, the 3D blade parameterization method and the self-organization map (SOM) based data mining technique. Using CHT, a numerical investigation was carried out to evaluate the aerothermal performance of C3X model, which consists of the blade passage, the blade solid domain and the internal coolant flow passages. The results calculated by the CHT method were validated by the experimental results. A new parameterization method for modeling the blade profile and cooling system has been developed. The optimization is intended to minimize the maximum blade temperature and the temperature gradient with constraints on the coolant mass flow rate, total mass flow rate and total pressure recovery coefficient of the blade. 27 Pareto solutions are obtained after the multidisciplinary design optimization for the gas turbine blade. Detailed aerothermal analysis shows that the thermal performance of the blade is significantly improved without deteriorating the related aerodynamic performance, thereby the correctness and effectiveness of our proposed optimization method are demonstrated. The SOM-based data mining on optimization design space is also applied to explore the trade-off relations between objective functions and correlations among design variables and objective function.

scholarly journals An alternative coating material for gas turbine blade for aerospace applications

2020 ◽  
Vol 1706 ◽  
pp. 012183
Author(s):  
Yajnesh M Poojari ◽  
Koustubh S Annigeri ◽  
Nilesh Bandekar ◽  
Kiran U Annigeri ◽  
Vinayak badiger ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Coating Material ◽  
Gas Turbine Blade ◽  
Aerospace Applications

Design and strengthening properties of different forging gas turbine blade materials

2021 ◽  
Author(s):  
Karnam Santosh Babu ◽  
K. Veera Raghavulu ◽  
S.P. Jani
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Gas Turbine Blade

Defect assessment in gas turbine blade coatings using non-contact thermography

2020 ◽  
Author(s):  
M. Mahesh Kumar ◽  
A.H.V. Pavan ◽  
R. Markandeya ◽  
Kulvir Singh
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Gas Turbine Blade ◽  
Defect Assessment
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