Prescribed-Curvature-Distribution Airfoils for the Preliminary Geometric Design of Axial-Turbomachinery Cascades

1992 ◽  
Author(s):  
Theodosios Korakianitis
Keyword(s):  
Turbine Blade ◽  
High Performance ◽  
Direct Method ◽  
Thickness Distribution ◽  
Turbine Blades ◽  
Leading Edge ◽  
Design Parameters ◽  
Blade Design ◽  
Curvature Distribution ◽  
Stagger Angle

Blade surfaces with continuous curvature and continuous slope of curvature minimize the possibility of flow separation, lead to improved blade designs, and reduce the direct and inverse blade-design iterations for the selection of isolated airfoils and gas-turbine-blade cascades. A method for generating two-dimensional blade shapes is presented. The geometry near the trailing edge is specified by an analytic polynomial, the main portion of the blade surface is mapped using as input a prescribed surface-curvature distribution, and the leading edge is specified as a thickness distribution added to a construction line. This procedure is similar for the suction and pressure surfaces, and by specification it constructs continuous slope-of-curvature surfaces that result in smooth surface-Mach-number and surface-pressure distributions. The method can be used to generate subsonic or supersonic airfoils for compressors and turbines, or isolated airfoils. The resulting geometric shapes can be used as inputs to various blade-design sequences. It is shown that, with other cascade-design parameters being equal, increasing the stagger angle of turbine blades results in more-front-loaded and thinner blades, and that there is an optimum stagger angle resulting in minimum wake thickness. The subsonic axial-turbine blade rows included for discussion in this paper have been designed by iterative modifications of the blade geometry to obtain a desirable velocity distribution. The blade-design method can be used to improve the aerodynamic and heat transfer performance of turbine cascades, and it can result in high-performance airfoils, even if using the direct method exclusively, in very few iterations.

Prescribed-Curvature-Distribution Airfoils for the Preliminary Geometric Design of Axial-Turbomachinery Cascades

1993 ◽  
Vol 115 (2) ◽  
pp. 325-333 ◽  
Author(s):  
T. Korakianitis
Keyword(s):  
Turbine Blade ◽  
High Performance ◽  
Direct Method ◽  
Thickness Distribution ◽  
Turbine Blades ◽  
Leading Edge ◽  
Design Parameters ◽  
Blade Design ◽  
Curvature Distribution ◽  
Stagger Angle

Blade surfaces with continuous curvature and continuous slope of curvature minimize the possibility of flow separation, lead to improved blade designs, and reduce the direct and inverse blade-design iterations for the selection of isolated airfoils and gas-turbine-blade cascades. A method for generating two-dimensional blade shapes is presented. The geometry near the trailing edge is specified by an analytic polynomial, the main portion of the blade surface is mapped using as input a prescribed surface-curvature distribution, and the leading edge is specified as a thickness distribution added to a construction line. This procedure is similar for the suction and pressure surfaces, and by specification it constructs continuous slope-of-curvature surfaces that result in smooth surface-Mach-number and surface-pressure distributions. The method can be used to generate subsonic or supersonic airfoils for compressors and turbines, or isolated airfoils. The resulting geometric shapes can be used as inputs to various blade-design sequences. It is shown that, with other cascade-design parameters being equal, increasing the stagger angle of turbine blades results in more front-loaded and thinner blades, and that there is an optimum stagger angle resulting in minimum wake thickness. The subsonic axial-turbine blade rows included for discussion in this paper have been designed by iterative modifications of the blade geometry to obtain a desirable velocity distribution. The blade-design method can be used to improve the aerodynamic and heat transfer performance of turbine cascades, and it can result in high-performance airfoils, even if using the direct method exclusively, in very few iterations.

Two- and Three-Dimensional Prescribed Surface Curvature Distribution Blade Design (CIRCLE) Method for the Design of High Efficiency Turbines, Compressors, and Isolated Airfoils

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
T. Korakianitis ◽  
M. A. Rezaienia ◽  
I. A. Hamakhan ◽  
A. P. S. Wheeler
Keyword(s):  
Turbine Blade ◽  
High Efficiency ◽  
Turbine Blades ◽  
Circle Method ◽  
Three Dimensional ◽  
Leading Edge ◽  
Surface Curvature ◽  
Blade Design ◽  
Compressor Blades ◽  
Curvature Distribution

The prescribed surface curvature distribution blade design (CIRCLE) method is presented for the design of two-dimensional (2D) and three-dimensional (3D) blades for axial compressors and turbines, and isolated blades or airfoils. The original axial turbine blade design method is improved, allowing it to use any leading-edge (LE) and trailing-edge (TE) shapes, such as circles and ellipses. The method to connect these LE and TE shapes to the remaining blade surfaces with curvature and slope of curvature continuity everywhere along the streamwise blade length, while concurrently overcoming the “wiggle” problems of higher-order polynomials is presented. This allows smooth surface pressure distributions, and easy integration of the CIRCLE method in heuristic blade-optimization methods. The method is further extended to 2D and 3D compressor blades and isolated airfoil geometries providing smooth variation of key blade parameters such as inlet and outlet flow angles, stagger angle, throat diameter, LE and TE radii, etc. from hub to tip. One sample 3D turbine blade geometry is presented. The efficacy of the method is examined by redesigning select blade geometries and numerically evaluating pressure-loss reduction at design and off-design conditions from the original blades: two typical 2D turbine blades; two typical 2D compressor blades; and one typical 2D isolated airfoil blade geometries are redesigned and evaluated with this method. Further extension of the method for centrifugal or mixed-flow impeller geometries is a coordinate transformation. It is concluded that the CIRCLE method is a robust tool for the design of high-efficiency turbomachinery blades.

Hierarchical Development of Three Direct-Design Methods for Two-Dimensional Axial-Turbomachinery Cascades

1993 ◽  
Vol 115 (2) ◽  
pp. 314-324 ◽  
Author(s):  
T. Korakianitis
Keyword(s):  
High Performance ◽  
Direct Method ◽  
Thickness Distribution ◽  
Leading Edge ◽  
Design Methods ◽  
Blade Design ◽  
Two Dimensional ◽  
The Third ◽  
Direct Design ◽  
Turbomachinery Cascades

The direct and inverse blade-design iterations for the selection of isolated airfoils and gas turbine blade cascades are enormously reduced if the initial blade shape has performance characteristics near the desirable ones. This paper presents the hierarchical development of three direct blade-design methods of increasing utility for generating two-dimensional blade shapes. The methods can be used to generate inputs to the direct- or inverse-blade-design sequences for subsonic or supersonic airfoils for compressors and turbines, or isolated airfoils. The examples included for illustration are typical modern turbine cascades, and they have been designed by the direct method exclusively. The first method specifies the airfoil shapes with analytical polynomials. It shows that continuous curvature and continuous slope of curvature are necessary conditions to minimize the possibility of flow separation, and to lead to improved blade designs. The second method specifies the airfoil shapes with parametric fourth-order polynomials, which result in continuous-slope-of-curvature airfoils, with smooth Mach number and pressure distributions. This method is time consuming. The third method specifies the airfoil shapes by using a mixture of analytical polynomials and mapping the airfoil surfaces from a desirable curvature distribution. The third method provides blade surfaces with desirable performance in very few direct-design iterations. In all methods the geometry near the leading edge is specified by a thickness distribution added to a construction line, which eliminates the leading edge overspeed and laminar-separation regions. The blade-design methods presented in this paper can be used to improve the aerodynamic and heat transfer performance of turbomachinery cascades, and they can result in high-performance airfoils in very few iterations.

Two- and Three-Dimensional Prescribed Surface Curvature Distribution Blade Design (CIRCLE) Method for the Design of High Efficiency Turbines, Compressors, and Isolated Airfoils

2011 ◽  
Author(s):  
T. Korakianitis ◽  
I. A. Hamakhan ◽  
M. A. Rezaienia ◽  
A. P. S. Wheeler
Keyword(s):  
Turbine Blade ◽  
High Efficiency ◽  
Turbine Blades ◽  
Circle Method ◽  
Three Dimensional ◽  
Leading Edge ◽  
Surface Curvature ◽  
Blade Design ◽  
Compressor Blades ◽  
Curvature Distribution

The prescribed surface curvature distribution blade design (CIRCLE) method is presented for the design of two-dimensional (2D) and three-dimensional (3D) blades for axial compressors and turbines, and isolated blades or airfoils. The original axial turbine blade design method is improved, allowing it to use any leading-edge (LE) and trailing-edge (TE) shapes, such as circles and ellipses. The method to connect these LE and TE shapes to the remaining blade surfaces with curvature and slope of curvature continuity everywhere along the streamwise blade length, while concurrently overcoming the “wiggle” problems of higher-order polynomials is presented. This allows smooth surface pressure distributions, and easy integration of the CIRCLE method in heuristic blade-optimization methods. The method is further extended to 2D and 3D compressor blades and isolated airfoil geometries providing smooth variation of key blade parameters such as inlet and outlet flow angles, stagger angle, throat diameter, LE and TE radii etc. from hub to tip. One sample 3D turbine blade geometry is presented. The efficacy of the method is examined by redesigning select blade geometries and numerically evaluating pressure-loss reduction at design and off-design conditions from the original blades: two typical 2D turbine blades; two typical 2D compressor blades; and one typical 2D isolated airfoil blade geometries are redesigned and evaluated with this method. Further extension of the method for centrifugal or mixed-flow impeller geometries is a coordinate transformation. It is concluded that the CIRCLE method is a robust tool for the design of high-efficiency turbomachinery blades.

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 %.

A Non-Dimensional Quasi-3D Blade Design Approach With Respect to Aerodynamic Criteria

2008 ◽  
Author(s):  
Amit Kumar Dutta ◽  
Peter Michael Flassig ◽  
Dieter Bestle
Keyword(s):  
Design Process ◽  
High Performance ◽  
Thickness Distribution ◽  
Computational Effort ◽  
Design Flow ◽  
Computational Time ◽  
Design Parameters ◽  
Angle Distribution ◽  
Blade Design ◽  
Additional Increase

The competition between aero-engine manufacturers has increased dramatically in the last decades. Saving computational time within the design process, which is equivalent to saving money, is of major importance for the industry. Talking about the aerodynamic compressor blading process, it becomes indispensable to go for new or alternative ways in designing blades in order to fulfill raised performance demands. The focus of this paper, therefore, is to propose a quasi-3D aerodynamic design concept with extended and improved parameterization of the aerofoil in order to support the industrial blading process. A Be´zier-surface is selected to parameterize the non-dimensional camber-line angle distribution along the blade chord from leading to trailing edge over the entire blade height in radial direction. Starting from scratch, the geometric blade build-up is completed by superposing the resulting camber-line with a given thickness distribution. For additional increase of design freedom, Be´zier-curves are used to radially parameterize blade inlet and outlet angles in their dimensionless form. The chosen parameterization of these distributions guarantees smooth blade shapes and geometry distributions with a minimum of design parameters. For optimization purpose it is essential to get performance information on the entire blade, however, with minimal computational effort. Facing this challenge, aerodynamic blade performance is evaluated by a two-dimensional blade-to-blade flow solver for specific sections on different radial blade heights. In order to speed up the blade design process, the flow calculations are realized by a distributed computing concept on a Linux high-performance cluster. All investigations are carried out for highly loaded controlled diffusion blades which are taken from an existing industrial research application. Since selected criteria such as mean loss at design point conditions and working range for off-design flow conditions represent contradicting design goals, the blade design problem is solved by means of a multi-objective problem formulation and a stochastic optimization algorithm. As a result Pareto-optimal trade-off solutions between conflicting design goals are shown where the design engineer can choose from according to his specific preferences.

Design Tuning of High Aspect Ratio Shrouded Turbine Blades

2008 ◽  
Author(s):  
Alexander N. Arkhipov ◽  
Andrey V. Pipopulo ◽  
Igor V. Putchkov
Keyword(s):  
Aspect Ratio ◽  
Turbine Blade ◽  
Natural Frequencies ◽  
Frequency Tuning ◽  
Turbine Blades ◽  
Mathematical Optimization ◽  
3D Models ◽  
Design Parameters ◽  
Blade Design ◽  
Cross Sectional

A large height to chord ratio, or aspect ratio, of industrial gas turbine blades, especially for the last rows, requires an increase of the blade natural frequencies above the 2nd Engine Order (EO). Generally this is possible only by utilizing a shrouded blade design. During the design process there are also several other mechanical factors, such as LCF, HCF, creep, shroud coupling, and aero efficiency, which have to be taken into consideration. It is shown that mathematical models of different complexity levels (1D / 3D models) can give comparable results for many important parameters if the boundary conditions for the 1D model are corrected by using the results of 3D model analysis. These parameters include quantities such as shroud contact pressure and coupling forces, the rotor speed at which full coupling is achieved, the first three blade natural frequencies, blade profile untwist moment and angle, and von Mises elastic stresses in critical sections. Thus a combination of 1D and 3D models can achieve a reduction of the time required for design of a shrouded turbine blade. The type of shroud design, the initial shroud clearance, and the contact surface angle are the important parameters for a shrouded turbine blade. The influence of these factors on dynamic response and lifetime prediction is non-linear and not always obvious, so a good blade design usually requires searching for an optimal combination of different design, technological and operational factors. Significant design parameters for blade frequency tuning are the radial distributions of cross-sectional geometrical characteristics and especially the radial distribution of the stagger angle. The latter one allows the designer to bring together or to move apart the first and the second vibration modes. More suitable parameter combinations are determined by the usage of mathematical optimization methods. The method presented and the corresponding techniques were used during design of shrouded blades for a few new turbines, where the length of the blade airfoil has exceeded 800mm.

Recent Advances in the Study of Film Cooling on the Gas Turbine Blade

2014 ◽  
Vol 971-973 ◽  
pp. 143-147 ◽  
Author(s):  
Ping Dai ◽  
Shuang Xiu Li
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Gas Turbines ◽  
High Performance ◽  
Leading Edge ◽  
Development Trend ◽  
Research Progress ◽  
Gas Turbine Blade ◽  
New Generation

The development of a new generation of high performance gas turbine engines requires gas turbines to be operated at very high inlet temperatures, which are much higher than the allowable metal temperatures. Consequently, this necessitates the need for advanced cooling techniques. Among the numerous cooling technologies, the film cooling technology has superior advantages and relatively favorable application prospect. The recent research progress of film cooling techniques for gas turbine blade is reviewed and basic principle of film cooling is also illustrated. Progress on rotor blade and stationary blade of film cooling are introduced. Film cooling development of leading-edge was also generalized. Effect of various factor on cooling effectiveness and effect of the shape of the injection holes on plate film cooling are discussed. In addition, with respect to progress of discharge coefficient is presented. In the last, the future development trend and future investigation direction of film cooling are prospected.

scholarly journals Redesigning a compressor inlet guide vane for 0 to 60 degree stagger angles

2021 ◽  
Author(s):  
Stephanie Waters
Keyword(s):  
Fuel Consumption ◽  
Guide Vane ◽  
Leading Edge ◽  
Aircraft Engine ◽  
Inlet Guide Vane ◽  
Pressure Loss Coefficient ◽  
Compressor Inlet ◽  
Curvature Distribution ◽  
Stagger Angle ◽  
Total Pressure Loss Coefficient

This report's objective is to reduce the total pressure loss coefficient of an inlet guide vane (IGV) at high stagger angles and to therefore reduce the overall fuel consumption of an aircraft engine. IGVs are usually optimized for cruise where the stagger angle is approximately 0 degrees. To reduce losses, four different methodologies were tested: increasing the leading edge radius, increasing the camber, creating a "drooped nose", and creating an "S" curvature distribution. A baseline IGV was chosen and modified using these methodologies to create 10 new IGV designs. CFX was used to perform a CFD analysis on all 11 IGV designs at 5 stagger angles from 0 to 60 degrees. Typical missions were analyzed and it was discovered that the new designs decreased the fuel consumption of the engine. The IGV with the "S" curvature and thicker leading edge was the best and decreased the fuel consumption by 0.24%.

Accelerated 3D Aerodynamic Optimization of Gas Turbine Blades

2014 ◽  
Author(s):  
Philipp Amtsfeld ◽  
Michael Lockan ◽  
Dieter Bestle ◽  
Marcus Meyer
Keyword(s):  
Turbine Blades ◽  
Three Dimensional ◽  
Optimization Process ◽  
Design Parameters ◽  
Blade Design ◽  
Aerodynamic Optimization ◽  
Multi Stage ◽  
Design Variables ◽  
Real Flow ◽  
Blade Model

State-of-the-art aerodynamic blade design processes mainly consist of two phases: optimal design of 2D blade sections and then stacking them optimally along a three-dimensional stacking line. Such a quasi-3D approach, however, misses the potential of finding optimal blade designs especially in the presence of strong 3D flow effects. Therefore, in this paper a blade optimization process is demonstrated which uses an integral 3D blade model and 3D CFD analysis to account for three-dimensional flow features. Special emphasis is put on shortening design iterations and reducing design costs in order to obtain a rapid automatic optimization process for fully 3D aerodynamic turbine blade design which can be applied in an early design phase already. The three-dimensional parametric blade model is determined by up to 80 design variables. At first, the most important design parameters are chosen based on a non-linear sensitivity analysis. The objective of the subsequent optimization process is to maximize isentropic efficiency while fulfilling a minimal set of constraints. The CFD model contains both important geometric features like tip gaps and fillets, and cooling and leakage flows to sufficiently represent real flow conditions. Two acceleration strategies are used to cut down the turn-around time from weeks to days. Firstly, the aerodynamic multi-stage design evaluation is significantly accelerated with a GPU-based RANS solver running on a multi-GPU workstation. Secondly, a response surface method is used to reduce the number of expensive function evaluations during the optimization process. The feasibility is demonstrated by an application to a blade which is a part of a research rig similar to the high pressure turbine of a small civil jet engine. The proposed approach enables an automatic aerodynamic design of this 3D blade on a single workstation within few days.

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