Design of Stress Constrained SiC/SiC Ceramic Matrix Composite Turbine Blades

2020 ◽  
Author(s):  
Robert J. Boyle ◽  
Pritheesh Gnanaselvam ◽  
Ankur H. Parikh ◽  
Ali A. Ameri ◽  
Jeffrey P. Bons ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Turbine Blades ◽  
Ceramic Matrix Composite ◽  
Aircraft Engine ◽  
Stress Constraints ◽  
Time Frame ◽  
Von Mises Stress ◽  
Efficiency Improvement ◽  
Low Aspect Ratio ◽  
Von Mises

Abstract The structural and aerodynamic performance of a a low aspect ratio SiC/SiC CMC High Pressure Turbine blade was determined. The application was a NASA notional single aisle aircraft engine to be available in the N+3, beyond 2030, time frame. The notional rpm was maintained, and to satisfy stress constraints the annulus area was constrained. This led to a low span blade. For a given clearance low span blade are likely to have improved efficiency when shrouded. The efficiency improvement due to shrouding was found to strongly depend on the axial gap between the shroud and casing. Axial gap, unlike clearance or reaction, is not a common parameter used to correlate the efficiency improvement due to shrouding. The zero clearance stage efficiency of the low aspect ratio turbine was 0.920. Structural analyses showed that the rotor blade could be shrouded without excessive stresses. The goal was to have blade stresses less than 100 MPa (14.5 ksi) for the unshrouded blade. Under some not very restrictive circumstances, such as blade stacking, a one-dimensional radial stress equation accurately predicted area averaged Von Mises stress at the blade hub. With appropriate stacking radial and Von Mises stresses were similar.

Design of Stress Constrained SiC/Sic Ceramic Matrix Composite Turbine Blades

2021 ◽  
Author(s):  
Robert Boyle ◽  
Pritheesh Gnanaselvam ◽  
Ankur H. Parikh ◽  
Ali Ameri ◽  
Jeffrey Bons ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Turbine Blades ◽  
Ceramic Matrix Composite ◽  
Aircraft Engine ◽  
Stress Constraints ◽  
Time Frame ◽  
Von Mises Stress ◽  
Efficiency Improvement ◽  
Low Aspect Ratio ◽  
Von Mises

Abstract The structural and aerodynamic performance of a a low aspect ratio SiC/SiC CMC High Pressure Turbine blade was determined. The application was a NASA notional single aisle aircraft engine to be available in the N+3, beyond 2030, time frame. The notional rpm was maintained, and to satisfy stress constraints the annulus area was constrained. This led to a low span blade. For a given clearance low span blade are likely to have improved efficiency when shrouded. The efficiency improvement due to shrouding was found to strongly depend on the axial gap between the shroud and casing. Axial gap, unlike clearance or reaction, is not a common parameter used to correlate the efficiency improvement due to shrouding. The zero clearance stage efficiency of the low aspect ratio turbine was 0.920. Structural analyses showed that the rotor blade could be shrouded without excessive stresses. The goal was to have blade stresses less than 100 MPa(14.5 ksi) for the unshrouded blade. Under some not very restrictive circumstances, such as blade stacking, a one-dimensional radial stress equation accurately predicted area averaged Von Mises stress at the blade hub. With appropriate stacking radial and Von Mises stresses were similar.

Design Considerations for Ceramic Matrix Composite High Pressure Turbine Blades

2019 ◽  
Author(s):  
Robert J. Boyle ◽  
Ankur H. Parikh ◽  
Vinod K. Nagpal
Keyword(s):  
High Pressure ◽  
Matrix Composite ◽  
Turbine Blades ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix ◽  
Aircraft Engine ◽  
Time Frame ◽  
Rotor Blades ◽  
High Pressure Turbine ◽  
Directional Variation

Abstract Issues associated with using SiC/SiC Ceramic Matrix Composite (CMC) materials for High Pressure Turbine (HPT) rotor blades are explored. SiC/SiC materials have higher temperature capability than current HPT superalloys. The strength versus temperature characteristics of SiC/SiC CMCs differs from that of superalloys. Stress analyses were done for a NASA specified notional single aisle aircraft engine blade to be available in the N+3 time frame, (beyond 2030). Stacking, the relative position of hub and tip sections, depends on both pressure and centrifugal forces, and material density. The effect of blade stacking on blade stresses is examined. The change in stresses as the rotation rate varies is examined. The change in engine weight, and thus fuel consumption, due to changes in engine size as the rpm changes is discussed. SiC/SiC CMC materials are generally not isotropic. The effect on stresses and strains of a directional variation in Young’s modulus is examined. Shrouding metallic HPT rotor blades is not common. Shrouding SiC/SiC CMC rotor blades may be feasible due to the lower density, and thus lower centrifugal loads, of SiC/SiC blades. The increase in stresses due to shrouding a SiC/SiC blade is discussed.

Low-Aspect-Ratio Rib Heat Transfer Coefficient Measurements in a Square Channel

1998 ◽  
Vol 120 (4) ◽  
pp. 831-838 ◽  
Author(s):  
M. E. Taslim ◽  
G. J. Korotky
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Aspect Ratio ◽  
Transfer Coefficient ◽  
Flow Direction ◽  
Turbine Blades ◽  
Transfer Coefficients ◽  
Square Channel ◽  
Low Aspect Ratio ◽  
The Heat Transfer Coefficient

Cooling channels, roughened with repeated ribs, are commonly employed as a means of cooling turbine blades. The increased level of mixing induced by these ribs enhances the convective heat transfer in the blade cooling cavities. Many previous investigations have focused on the heat transfer coefficient on the surfaces between these ribs and only a few studies report the heat transfer coefficient on the rib surfaces themselves. The present study investigated the heat transfer coefficient on the surfaces of round-corner, low-aspect-ratio (ARrib = 0.667) ribs. Twelve rib geometries, comprising three rib height-to-channel hydraulic diameters (blockage ratios) of 0.133, 0.167, and 0.25 as well as three rib spacings (pitch-to-height ratios) of 5, 8.5, and 10 were investigated for two distinct thermal boundary conditions of heated and unheated channel walls. A square channel, roughened with low-aspect-ratio ribs on two opposite walls in a staggered manner and perpendicular to the flow direction, was tested. An instrumented copper rib was positioned either in the middle of the rib arrangements or in the furthest upstream location. Both rib heat transfer coefficient and channel friction factor for these low-aspect-ratio ribs were also compared with those of square ribs, reported previously by the authors. Heat transfer coefficients of the furthest upstream rib and that of a typical rib located in the middle of the rib-roughened region of the passage wall were also compared.

scholarly journals Effect of secondary crystal orientations on the deformation anisotropy for nickel-based single-crystal plate with notch feature

2019 ◽  
Vol 54 (1) ◽  
pp. 54-64 ◽  
Author(s):  
Yu Zhai ◽  
Muhammad Kashif Khan ◽  
José Correia ◽  
Abílio MP de Jesus ◽  
Zhiyong Huang ◽  
...  
Keyword(s):  
Single Crystal ◽  
Deformation Process ◽  
Crystal Orientation ◽  
Turbine Blades ◽  
Von Mises Stress ◽  
Slip Systems ◽  
Nickel Based Superalloy ◽  
Crystal Orientations ◽  
Single Crystal Plate ◽  
Von Mises

The effects of the secondary crystal orientations on the nickel-based single-crystal superalloy turbine blades were investigated. The stress concentration features were used for investigation of the optimal secondary crystal orientation leading to the higher strength of the single-crystal turbine blades. The crystal plastic finite element method coupled with micromechanics constitutive model is applied to study the effect of secondary crystal orientation on plastic deformation and mechanical behavior around the cooling holes and notches with the primary (load) orientation fixed at [001] direction. For nickel-based superalloy plates with holes or notches, the secondary crystal orientation effect on the strength needs to be clarified at various load levels. The maximum von Mises stress in the single-crystal alloy varies significantly with variation in the secondary crystal orientations. It was found that only two slip systems dominate the deformation process of the material owing to their favorable orientation with loading. The secondary orientation of 45° was identified with lowest resolved shear stress in the dominating slip systems and potential of producing higher strength for single-crystal turbine blades.

Topology optimization of structures subject to self-weight loading under stress constraints

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Renatha Batista dos Santos ◽  
Cinthia Gomes Lopes
Keyword(s):  
Topology Optimization ◽  
Stress Constraints ◽  
Topological Derivative ◽  
The Self ◽  
Von Mises Stress ◽  
Stress Constraint ◽  
Content Type ◽  
Derivative Method ◽  
Von Mises ◽  
Weight Loading

PurposeThe purpose of this paper is to present an approach for structural weight minimization under von Mises stress constraints and self-weight loading based on the topological derivative method. Although self-weight loading topology has been the subject of intense research, mainly compliance minimization has been addressed.Design/methodology/approachThe resulting minimization problem is solved with the help of the topological derivative method, which allows the development of efficient and robust topology optimization algorithms. Then, the derived result is used together with a level-set domain representation method to devise a topology design algorithm.FindingsNumerical examples are presented, showing the effectiveness of the proposed approach in solving a structural topology optimization problem under self-weight loading and stress constraint. When the self-weight loading is dominant, the presence of the regularizing term in the formulation is crucial for the design process.Originality/valueThe novelty of this research work lies in the use of a regularized formulation to deal with the presence of the self-weight loading combined with a penalization function to treat the von Mises stress constraint.

Efficiency improvement of a CAES low aspect ratio radial inflow turbine by NACA blade profile

2019 ◽  
Vol 138 ◽  
pp. 1214-1231 ◽  
Author(s):  
Xing Wang ◽  
Wen Li ◽  
Xuehui Zhang ◽  
Yangli Zhu ◽  
Zhitao Zuo ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Efficiency Improvement ◽  
Blade Profile ◽  
Low Aspect Ratio ◽  
Radial Inflow Turbine

The Control of Shroud Leakage Flows to Reduce Aerodynamic Losses in a Low Aspect Ratio, Shrouded Axial Flow Turbine

2000 ◽  
Author(s):  
A. M. Wallis ◽  
J. D. Denton ◽  
A. A. J. Demargne
Keyword(s):  
Aspect Ratio ◽  
Turbine Blades ◽  
Significant Proportion ◽  
Axial Flow ◽  
Experimental Investigations ◽  
Leakage Flow ◽  
Leakage Flows ◽  
Low Aspect Ratio ◽  
Leakage Fraction ◽  
Aerodynamic Losses

The losses generated by fluid leaking across the shrouds of turbine blade rows are known to form a significant proportion of the overall loss generated in low aspect ratio turbines. The use of shrouds to encase the tips of turbine blades has encouraged the development of many innovative sealing arrangements, all of which are intended to reduce the quantity of fluid (the leakage fraction) leaking across the shroud. Modern sealing arrangements have reduced leakage fractions considerably, meaning that further improvements can only be obtained by controlling the leakage flow in such a way so as to minimise the aerodynamic losses incurred by the extraction and re-injection of the leakage flow into the mainstream. There are few published experimental investigations on the interaction between mainstream and leakage flows to provide guidance on the best means of managing the leakage flows to do this. This paper describes the development and testing of a strategy to turn the fluid leaking over shrouded turbine rotor blade rows with the aim of reducing the aerodynamic losses associated with its re-injection into the mainstream flow. The intent was to extract work from the leakage flow in the process. A four stage research turbine was used to test in detail the sealing design resulting from this strategy. A reduction in brake efficiency of 3.5% was measured. Further investigation suggested that much of the increase in loss could be attributed to the presence of axial gaps upstream and downstream of the shroud cavity which facilitated the periodic ingress and egress of mainstream fluid into the shroud cavity under the influence of the rotor potential field. This process was exacerbated by reductions in the leakage fraction.

scholarly journals Low-Aspect-Ratio Rib Heat Transfer Coefficient Measurements in a Square Channel

1997 ◽  
Author(s):  
M. E. Taslim ◽  
G. J. Korotky
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Aspect Ratio ◽  
Transfer Coefficient ◽  
Flow Direction ◽  
Turbine Blades ◽  
Transfer Coefficients ◽  
Square Channel ◽  
Low Aspect Ratio ◽  
The Heat Transfer Coefficient

Cooling channels, roughened with repeated ribs, are commonly employed as a means of cooling turbine blades. The increased level of mixing induced by these ribs enhances the convective heat transfer in the blade cooling cavities. Many previous investigations have focused on the heat transfer coefficient on the surfaces between these ribs and only a few studies report the heat transfer coefficient on the rib surfaces themselves. The present study investigated the heat transfer coefficient on the surfaces of round-corner, low-aspect-ratio (ARrib = 0.667) ribs. Twelve rib geometries, comprising of three rib height-to-channel hydraulic diameter (blockage ratios) of 0.133, 0.167, and 0.25 as well as three rib spacings (pitch-to-height ratios) of 5, 8.5, and 10 were investigated for two distinct thermal boundary conditions of heated and unheated channel walls. A square channel, roughened with low-aspect-ratio ribs on two opposite walls in a staggered manner end perpendicular to the flow direction was tested. An instrumented copper rib was positioned either in the middle of the rib arrangements or in the furthest upstream location. Rib heat transfer coefficient as well as the channel friction factor for these low-aspect-ratio ribs were also compared with those of square ribs, reported previously by the authors. Heat transfer coefficients of the furthest upstream rib and that of a typical rib located in the middle of the rib-roughened region of the passage wall were also compared.

Finite Element Analysis for Turbine Blades with Contact Problems

2016 ◽  
Vol 33 (4) ◽  
Author(s):  
Yuan-Jian Yang ◽  
Liang Yang ◽  
Hai-Kun Wang ◽  
Shun-Peng Zhu ◽  
Hong-Zhong Huang
Keyword(s):  
Finite Element ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Contact Problems ◽  
Element Model ◽  
Von Mises Stress ◽  
Aerodynamic Load ◽  
Element Analysis ◽  
Von Mises ◽  
Three Dimensional Finite Element

AbstractTurbine blades are one of the key components in a typical turbofan engine, which plays an important role in flight safety. In this paper, we establish a establishes a three-dimensional finite element model of the turbine blades, then analyses the strength of the blade in complicated conditions under the joint function of temperature load, centrifugal load, and aerodynamic load. Furthermore, contact analysis of blade tenon and dovetail slot is also carried out to study the stress based on the contact elements. Finally, the Von Mises stress-strain distributions are obtained to acquire the several dangerous points and maximum Von Mises stress, which provide the basis for life prediction of turbine blade.

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