Impact of Foreign Object Damage to Leading Edge on Fatigue Capability of CMC Turbine Vanes

2019 ◽  
Author(s):  
Kenro Obuchi ◽  
Fumiaki Watanabe ◽  
Hiroshi Kuroki ◽  
Kazuyoshi Arai
Keyword(s):  
Stress Concentration ◽  
Test Piece ◽  
Impact Resistance ◽  
Leading Edge ◽  
Strength Reduction ◽  
Foreign Object ◽  
Turbine Vanes ◽  
Turbine Vane ◽  
Hcf Strength ◽  
The Impact

Abstract Ceramic matrix composites (CMCs) are expected to make turbine components lighter because they have lower density than nickel-based super alloys which have been used for turbine components. Also they are expected to improve the efficiency of gas turbine engines by realizing higher turbine inlet temperature (TIT), because they have higher temperature capability. One of the technical issues of CMCs is that they have relatively low impact resistance comparing with nickel-based alloy. In the previous work, it was estimated that the foreign object damage (FOD) on CMC turbine vanes under the actual engine condition is less than 0.36-mm-depth. The concern of such damaged CMC turbine vanes is a decrease in a fatigue capability due to the dent particular to the leading edge (L/E). The fatigue strength reduction can be caused by the stress concentration due to the dented shape and the oxidation due to the coating spallation. There are various works about the impact resistance or the fatigue capability of CMCs, but there are little works which assess the fatigue capability of CMCs which was damaged by foreign object. The objective of this work was to clarify the impact of FOD to L/E on the fatigue capability of SiC/SiC CMC turbine vane. The tension-tension low cycle fatigue (LCF) tests and high cycle fatigue (HCF) tests were conducted using four types of test pieces at elevated temperature in the steam environment. The first one was smooth test piece with anti-oxidation coating, the second one was the test piece which had notch with coating, the third one was the test piece which had notch without coating at notched area and the fourth one was the test piece which was damaged by dropped weight test simulating FOD. The result showed that impact of stress concentration due to notch shape on fatigue capability is small. It was also cleared that uncoated condition did not have impact on the LCF capability but had impact on the HCF capability. The HCF strength reduction of TP without coating to the TP with coating was about 35% at 107 cycles. More fiber breakage was observed at the fracture surface of the TP without coating tested in HCF condition, on the other hand more fiber pullout was observed at that of other TPs. The results suggest that the HCF strength reduction was caused by oxidation when the bare CMC was exposed by FOD. From this work, it was concluded that the loss of coating due to FOD impacted on HCF strength of CMC turbine vane, but it can be accepted because turbine vane is normally designed so that it can endure the stress concentration at L/E due to FOD (typically kt = 3).

Impact Test for the Leading Edge of CMC Vane Based on Actual Aircraft Engine Field Data

2018 ◽  
Author(s):  
Kenro Obuchi ◽  
Fumiaki Watanabe ◽  
Hiroshi Kuroki ◽  
Hiroyuki Yagi ◽  
Kazuyoshi Arai
Keyword(s):  
Impact Test ◽  
Impact Resistance ◽  
Leading Edge ◽  
Aircraft Engine ◽  
Aircraft Engines ◽  
Turbine Vanes ◽  
Turbine Vane ◽  
Nickel Based Alloy ◽  
Weight Impact ◽  
The Impact

Ceramic matrix composites (CMCs) have lower density and a higher service temperature limit than nickel based alloys which have been used for turbine components of aircraft engines. These properties of CMCs have the potential to reduce the weight of turbine components and improve turbine thermal efficiency with a higher turbine inlet temperature (TIT). One of the technical issues of the CMC turbine vane is a relatively lower impact resistance than nickel based alloy turbine vanes. There are various previous works about impact resistance of CMCs, but there is little work that assumed actual engine conditions. The objective of this work was to verify the resistance of SiC/SiC CMC turbine vane to the impact phenomena that occur in the actual aircraft engine. The field damage survey was conducted on actual metal turbine vanes of commercial engines overhauled in IHI. The survey made it clear that the typical damage was less-than-0.127-mm-dent at the leading edge. In addition, the dropped weight impact test using the actual turbine airfoil which is made from a nickel based alloy was conducted at ambient temperature. The amount of energy required to make the dent of a certain size that was observed in actual metal turbine vanes was estimated. Then, the dropped weight impact test using the CMC test piece with a leading edge shape was conducted at the impact energy estimated by the metal turbine airfoil. The results showed that the failure mode of the CMC test piece was local damage with dents of a certain size and not a catastrophic failure mode. From this work, the damage to be assumed on CMC vane in actual aircraft engines was identified. As a future task, the effect of the damage to the fatigue capability of CMC turbine vanes needs to be investigated.

Simulated Foreign Object Damage on Blade Aerofoils: Real Damage Investigation

2008 ◽  
Author(s):  
Pierangelo Duo´ ◽  
Christian Pianka ◽  
Andrej Golowin ◽  
Matthias Fueller ◽  
Roger Schaefer ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Numerical Models ◽  
Research Work ◽  
Experimental Simulation ◽  
Foreign Object ◽  
Foreign Object Damage ◽  
Special Cases ◽  
Hcf Strength ◽  
Residual Fatigue ◽  
The Impact

During operating service, gas turbine aero-engines can ingest small hard particles which typically produce damage to the aerofoils. If the damage found is a tear or a perforation at the leading edge, it is known as a Foreign Object Damage or FOD and this leads to a reduction of the subsequent High-Cycle-Fatigue (HCF) strength. The objective of research work in this area is to assess the effect of FOD on the residual fatigue strength of compressor blades and to provide predictive tools for engineering judgment. The methodology followed is normally to carry out experimental simulation of FOD, followed by fatigue tests to assess subsequent performance. To date, research related to fatigue following FOD events has concentrated on HCF loading and the impact geometry is frequently that of a sphere against a flat surface or the edge of a blade-like specimen. Both of these aspects do not correspond to the worst cases of real FOD. Here it is intended to investigate the effect of a V-notch geometry, which is more representative of severe FOD found in service. Alongside this, numerical models can be used to simulate the damage and to evaluate the residual stress field. In addition analytical model are used to predict the residual fatigue strength. The current work explains the development of a new rig impact test and discusses the improvements necessary to obtain a sufficient repeatability of the impacts. From the experience gained with a gas gun, an alternative method using a pistol and a barrel, capable of achieving the necessary velocity of simulated FOD, was developed. The applied velocity was in the range of 250m/s to 300m/s and a technique to describe the impact is here discussed. Furthermore the introduction of a high speed camera has allowed to have a complete description of the impact scene and to better understand the impact. The impacted blades were measured and HCF tested. As a result, this has produced a large scatter in the residual fatigue strength. The current method to describe a notch using a 2D approach, which was applied to several geometries of notches, is here critically reviewed. The proposed method would incorporate a more sophisticated method, which reconstruct the real geometry using optical measurement. This latter measurement can fully describe the 3D geometry, showing particularly zones inside the notch where compressive residual might appears. Tears and shear of the material can also be described by applying this technique. The findings are compared with the residual HCF strength and the results are compared to special cases of HCF to justify the results out of theoretical prediction.

scholarly journals Cooling Characteristics of Film Cooled Turbine Vane Having Multi-Row of Ejection Holes

1978 ◽  
Author(s):  
K. Sakata ◽  
H. Usui ◽  
K. Takahara
Keyword(s):  
Flow Distribution ◽  
Leading Edge ◽  
Coolant Flow ◽  
Edge Region ◽  
Flow Ratio ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Turbine Vanes ◽  
Turbine Vane ◽  
Cooling Hole

Film-cooled turbine vanes having 14 rows of round holes were designed. Two-dimensional cascade tests of two kinds of scaled vanes were carried out and cooling performances were obtained. Coolant flow distributions were controlled by the impingement and plenum chamber configuration. Higher cooling effectiveness than 0.65 was obtained for the coolant flow ratio of 4.5 percent. And it was clarified that the distributions of cooling effectiveness of the vane surface was governed by the configuration of coolant flow distribution to the cooling hole rows, and, that with using relatively greater amount of coolant to the leading edge region, higher cooling performance can be obtained. Also, numerical calculations of cooling performance and prediction for turbine application were presented.

Computational Analysis of a Novel Cooling Scheme for Ultra Compact Combustor Turbine Vanes

2017 ◽  
Author(s):  
Brian T. Bohan ◽  
Marc D. Polanka ◽  
James L. Rutledge
Keyword(s):  
Film Cooling ◽  
Leading Edge ◽  
External Pressure ◽  
Cold Region ◽  
Stagnation Region ◽  
Engine Efficiency ◽  
Turbine Vanes ◽  
Turbine Vane ◽  
Cooling Hole ◽  
Computational Fluid Dynamics Cfd

The Ultra Compact Combustor (UCC) has the potential to improve overall engine efficiency at a reduced size, while offering a unique component configuration that can allow for novel cooling of turbine vanes located below the circumferential cavity. In this configuration the leading edge of the turbine vane is located upstream of the combustor, with hot gases impinging near 1/5-chord and aft to the trailing edge. Therefore the leading edge remains in a cold region of the flow allowing openings in the stagnation region of the vane to ingest cool core flow. A computational fluid dynamics (CFD) analysis is presented that analyzed stagnation fed cooling variations for the current UCC turbine vane. The variants included several internal only cooling schemes and one external film cooling scheme. The internal only variants showed that with proper component geometry the internal pressure could exceed the external pressure downstream from the leading edge. The film cooling hole variant showed that coolant did in fact exit the vane through 3 of the 8 cooling holes in a similar fashion as a compressor fed scheme. The determination if coolant would exit the holes was highly dependent on the external pressure gradient on the vane.

scholarly journals Stress analysis of V-notches with and without cracks, with application to foreign object damage

2003 ◽  
Vol 38 (5) ◽  
pp. 429-441 ◽  
Author(s):  
D Nowell ◽  
D Dini ◽  
P Duó
Keyword(s):  
Stress Intensity ◽  
Stress Concentration ◽  
Fatigue Cracks ◽  
Leading Edge ◽  
Foreign Object ◽  
Foreign Object Damage ◽  
Hard Particles ◽  
Notch Stress ◽  
Concentration Factors ◽  
Stress Concentration Factors

Gas turbine engines can be subject to ingestion of small hard particles, leading to foreign object damage. This can take the form of sharp V-notches in the leading edge of blades and there is a need to predict the initiation and propagation behaviour of fatigue cracks growing from the base of the notch. The notch geometry is quite extreme and is not normally covered in standard references for notch stress concentration factors. Similarly, stress intensity factor solutions for this geometry are not widely available. This paper uses the dislocation density approach to solve the two-dimensional elastic problem of a V-notch with a radiused root. Stress concentration factors are found for the notch itself, and stress intensity factors are determined for cracks growing away from the notch for cases of applied and residual stress distributions. Comparisons are made with existing notch solutions from the literature.

Effect of Blade Geometry and Foreign Object Kinetic Energy on Blades Damage

2010 ◽  
Author(s):  
Mickhail S. Nikhamkin ◽  
Leonid V. Voronov ◽  
Irina V. Semenova
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Kinetic Energy ◽  
Leading Edge ◽  
Material Behavior ◽  
Plastic Strain Rate ◽  
Problem Solution ◽  
Foreign Object ◽  
The Impact ◽  
Blade Leading Edge

One of the main reasons of engine failure is foreign object damage (FOD) of compressor blades. Engine manufactures are constantly searching for blade endurance increasing methods. The problem solution requires investigation in the field of the structural factor effects on the blade damageability. The paper describes numerical analysis method of the damage process. Based on “the typical damage case” concept, this method can simulate typical blade damages: dents, tears, notches. The numerical analysis is performed by the finite element method (FEM). Material behavior is described with an elastic-plastic strain rate dependent model. Blade damage numerical model is thoroughly verified by the results of special experiments. To implement the experimental modeling, actual blades were damaged, a special experimental setup based on a pneumatic gun being used. The foreign object kinematic parameters before and after the impact, a blade leading edge displacements and residual deformation fields registered in the experiment are used as verification criteria for the numerical model. The blade leading edge thickness and a foreign object energy effect on the blade damageability is investigated. The research showed there are some foreign object kinetic energy critical values at which the damage mechanism and type are changed.

Foreign Objects Damage on the Leading Edge of the Blade with Centrifugal Preload

2011 ◽  
Vol 148-149 ◽  
pp. 958-962
Author(s):  
Dong Mei Yin ◽  
Zhen Xiao Li
Keyword(s):  
Leading Edge ◽  
Relaxation Method ◽  
Foreign Object ◽  
Nonlinear Dynamic Model ◽  
Foreign Object Damage ◽  
Foreign Objects ◽  
Dynamic Relaxation Method ◽  
The Moment ◽  
In The Beginning ◽  
The Impact

The influence of centrifugal prestress on the foreign object damage of engine blades was analyzed by numerical simulation. A nonlinear dynamic model for foreign object damage of blade with centrifugal prestress was established. And the dynamic relaxation method was used to obtain the initial stress and displacement field of blade in the beginning of the dynamic analysis of impact. Numerical simulations of foreign objects impacting on the leading edges of the blades under different centrifugal preloads were carried out. The results indicate that the local plastic deformation on the impact location of blade with centrifugal preload, which is produced at the moment of impact, is decreasing with the increase of the preload. The growth of crack produced on the lead edge of blade is accelerated with the preload increasing.

scholarly journals Concept of Computer-Aided Assessment of the Technical Condition of Operated Gas Turbine Vanes

2018 ◽  
Vol 25 (3) ◽  
pp. 104-112 ◽  
Author(s):  
Mariusz Bogdan ◽  
Marcin Derlatka ◽  
Józef Błachnio
Keyword(s):  
Structural Changes ◽  
Image Data ◽  
Leading Edge ◽  
Technical Condition ◽  
Transient Condition ◽  
Color Analysis ◽  
Multi Stage ◽  
Turbine Vanes ◽  
Software Localization ◽  
The Impact

Abstract The article presents a multi-stage algorithm for automatic (without any human, user – diagnostician intervention) detection of vanes-blades (technical objects) and their surfaces on a digital image, combined with color analysis, aimed at determining the technical condition of the tested turbine elements. The images recorded with the use of a camera, containing previously dismantled from the turbine operated stator vanes, were used as the exemplary analysis material. The paper presents the algorithm for the detection of the vanes’ airfoil surfaces with the impact of the applied techniques and methods of image processing and analysis on the final result (software localization of the vane’s trailing and leading edge), Then, the obtained image data, including the structural changes of both the vane’s coating and material (metallographic testing) were correlated with the surface colour scheme (colour segmentation based on the YCbrCr colour space model). Thanks to this approach, areas on the surface of the blade were distinguished, characteristic for proper, overheated and transient condition.

Leading Edge Cooling Performance of an Integrated Cooling Configuration

2008 ◽  
Author(s):  
Takahiro Bamba ◽  
Takao Kumagai ◽  
Fujio Mimura ◽  
Takashi Yamane ◽  
Yoshitaka Fukuyama ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Test Piece ◽  
Infrared Camera ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Pin Fin ◽  
Turbine Vane ◽  
Simulated Condition ◽  
Cooling Air

This paper presents the experimental work on the leading edge cooling performance of an integrated impingement and pin-fin cooling configuration. Experiments are conducted for seven different spatial geometries under the simulated condition of 1400 degree Celsius-class actual turbine vane leading edge with the temperature ratio of 2.1. The Reynolds number of the hot gas side was 91000 and the cooling air Reynolds number was varied in the range of 5900–47000. The test piece surface temperature distributions were measured using an infrared camera with the correction by a thermocouple embedded on the test piece surface. The cooling effectiveness obtained from the experiments showed the superior cooling performance by the pin-fin integration. The effect of the cooling effectiveness enhancement was more than the cooling surface area increment. The detailed analyses of the cooling performance and the pressure loss characteristics are discussed.

scholarly journals A Comprehensive Numerical Investigation on the Mechanical Performance of Hybrid Composite Tidal Current Turbine under Accidental Impact

2020 ◽  
Vol 17 (4) ◽  
pp. 8338-8350
Author(s):  
H. Laaouidi ◽  
M. Tarfaoui ◽  
M. Nachtane ◽  
M. Trihi ◽  
O. Lagdani
Keyword(s):  
Hybrid Composite ◽  
Mechanical Performance ◽  
Impact Resistance ◽  
Leading Edge ◽  
Matrix Cracking ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Internal Surfaces ◽  
Tidal Turbine ◽  
The Impact

The composite tidal turbine nozzle can be exposed to impact loads during maintenance or installation operations, which may result in invisible damage. Therefore, it is very important to analyse the induced damage in order to conceive hybrid composite nozzles with better resistance to damage. The low-velocity impact behaviour (LVI) of a carbon/glass hybrid composite nozzle has been investigated based on this motivation. The configurations of stacking sequences were constituted of glass and carbon fibers. The results acquired were compared between five various laminated. Indeed, the impact was studied in the leading edge region of the nozzle. The damaged laminates were inspected by the finite element method (FEM) based on Hashin failure criterion using the ABAQUS software. The energy conservation of the nozzle was verified to validate the numerical model. Futhermore, the effect of accidental impact on dynamic response and the damage induced on a hybrid composite nozzle have been investigated. According to results, the formation of damage like matrix cracking on the external/internal surfaces and radial cracking may occur. In addition, the hybrid nozzle with CCC (carbon/carbon/carbon), and CGG (carbon/glass/glass) stacking has greater impact resistance compared to other configurations.

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