scholarly journals Effect of Laser Process on Microstructure and Fatigue Resistance of Steam Turbine Blade

2022 ◽  
Vol 961 (1) ◽  
pp. 012017
Author(s):  
Zaman A. Abdulwahab ◽  
Sami I. Jafar ◽  
Sami A. Ajeel
Keyword(s):  
Steam Turbine ◽  
Fatigue Resistance ◽  
Turbine Blades ◽  
Average Power ◽  
Pulse Frequency ◽  
Electricity Production ◽  
Wide Range ◽  
Before And After ◽  
Steam Turbine Blade ◽  
Lifting Equipment

Abstract The steal turbine blades, operating in steam electricity production plants are subjected to periodic circular stresses that cause fatigue failure with the passage of time. The chemical composition so steam turbine blades show that is steel 52 it has a wide range of applications, mostly in welded construction, All kinds of welded construction, wind turbines, load-lifting equipment, platform components, cranes, bridge components, and structures. This research aims to study the microstructure of these turbine blades before and after the occurrence of fatigue, and for the purpose of improvement the fatigue resistance, the blades were treated with a laser and the amount of improvement in fatigue resistance was calculated and also the change in the microstructure after laser treatment was studied. The remelting process applied with this parameter Pulse energy = 8 joules, Pulse width = 4.5 Ms., Pulse frequency = 12 Hz, Laser Average Power = 96 W, Laser peak power = 1.78 KW. The results show, after remelting process the microstructure of the specimen is smooth and increase the cyclic of fatigue comparison with specimen without leaser remelting process. So, the fatigue resistance is increased.

scholarly journals Influence Of Laser Cladding on Behavior of Fatigue and Fatigue Corrosion

2022 ◽  
Vol 961 (1) ◽  
pp. 012035
Author(s):  
Zaman A. Abdulwahab ◽  
Sami A. Ajeel ◽  
Sami I. Jafar
Keyword(s):  
Laser Cladding ◽  
Turbine Blades ◽  
Average Power ◽  
Pulse Frequency ◽  
Jet Engines ◽  
Inconel 600 ◽  
Laser Cladding Process ◽  
Wide Range ◽  
Before And After ◽  
Fatigue Corrosion

Abstract Nickle based super alloys such as Inconel 600 are being extensively used to manufacture turbine blades for jet engines since their superior mechanical characteristics at higher working temps. The chemical composition of steam turbine blades show that is steel 52 it has a wide range of Energy, Tanks, Rail, Yellow Goods, Engineering, Bridges, Construction, applications. Laser cladding seems to be a surfacing method that uses lasers to improve the characteristics of a component’s surface and/or renew it. Laser cladding involves absorption of laser light that melts a small area of the substrates against which the substance was being introduced and fuses the coating substance to the substrates, resulting in the formation of a new layer. This research aims to investigate the fatigue and fatigue corrosion behavior of these turbine blades before and after exposure to laser cladding. The cladding process applied with this parameter Pulse energy = 11 joules, Pulse width = 6 Ms., Pulse frequency = 12 Hz, Laser Average Power = 132 W, Laser peak power = 1.83 KW. The results show, after cladding process the microstructure of the specimen is smooth and increase the cyclic of fatigue comparison with specimen without laser cladding process. So, the fatigue resistance is increased.

Studies on Determination of Natural Frequencies of Industrial Turbine Blades

1995 ◽  
Author(s):  
Mahesh M. Bhat ◽  
V. Ramamurti ◽  
C. Sujatha
Keyword(s):  
Steam Turbine ◽  
Dynamic Behavior ◽  
Turbine Blade ◽  
Natural Frequencies ◽  
Complex Structure ◽  
Turbine Blades ◽  
Blade Root ◽  
Steam Turbine Blade ◽  
Manufacturing Tolerances

Abstract Steam turbine blade is a very complex structure. It has geometric complexities like variation of twist, taper, width and thickness along its length. Most of the time these variations are not uniform. Apart from these geometric complexities, the blades are coupled by means of lacing wire, lacing rod or shroud. Blades are attached to a flexible disc which contributes to the dynamic behavior of the blade. Root fixity also plays an important role in this behavior. There is a considerable variation in the frequencies of blades of newly assembled turbine and frequencies after some hours of running. Again because of manufacturing tolerances there can be some variation in the blade to blade frequencies. Determination of natural frequencies of the blade is therefore a very critical job. Problems associated with typical industrial turbine bladed discs of a 235 MW steam turbine are highlighted in this paper.

Evaluation of Steam Turbine Blades Surface Cracks Detectability by Nondestructive Methods

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
J. Veselá ◽  
P. Mareš ◽  
P. Zahrádka ◽  
J. Patera
Keyword(s):  
Steam Turbine ◽  
Rayleigh Waves ◽  
Crack Detection ◽  
Turbine Blades ◽  
Surface Cracks ◽  
Advantages And Disadvantages ◽  
Array Probe ◽  
Steam Turbine Blade ◽  
Corrosion Pitting ◽  
Steam Turbine Blades

Abstract This article describes methods suitable for crack detection on low pressure steam turbine blades, not including the blade root. These cracks, which are initiated in the corrosion pitting, can cause serious damage to the steam turbine blade leading to its breakaway. Therefore, the detection of these cracks on the early stages of blade fracture is very important. Several methods for detecting of surface cracks (ultrasonic Rayleigh waves, eddy current with flexible array probe, etc.) has been tested on artificial flaws, which were manufactured into turbine blades. The comparison of all these methods is described as well as the evaluation of their advantages and disadvantages. Simulations of ultrasonic testing are also presented in this article.

Experimental Friction Damping Characteristic of a Steam Turbine Blade Coupled by Shroud and Snubber at Standstill Set-Up

2012 ◽  
Author(s):  
Jun Wu ◽  
Yonghui Xie ◽  
Di Zhang ◽  
Minghui Zhang
Keyword(s):  
Steam Turbine ◽  
Turbine Blade ◽  
Rotational Speed ◽  
Damping Ratio ◽  
Turbine Blades ◽  
Contact Forces ◽  
Normal Contact ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
Steam Turbine Blade

In order to avoid the high cycle fatigue which leads to the failure of turbine blades, friction structural damping has been widely used in turbine blade designs to reduce vibratory stresses by energy dissipation. A method is developed here to analyze the influence of friction structural damping on the vibration characteristics of turbine blades. Vibratory responses of a long steam turbine blade with shroud and snubber are studied. Finite element contact analysis of the steam turbine blades which are modeled in 3-D solid elements is conducted to obtain the normal contact force on the shroud contact surface and snubber contact surface of adjacent blades under five different rotational speeds (2100rpm, 2200rpm, 2413rpm, 2600rpm and 3000rpm). A rig for the tests of non-rotating turbine blade with friction damping structure is built. The normal contact forces of the shroud and snubber are applied to the blade according to numerical results. The response curves and modal damping ratios of the blade under different normal contact forces, which each one is related to a different rotational speed, are obtained. The experimental results show that with increases in rotational speed, modal damping ratio of the blade experiences an increasing period followed by a decreasing period while the resonance amplitude decreases first and then increases when there is only shroud contact. The effects are similar when there are both shroud and snubber contact. The modal damping ratio of the blade is basically identical with that of the uncoupled blade for the rotational speed above 2600rpm. For this range of rotational speed, the resonance frequency increases with the increase of rotational speed, and the changes of the resonance frequency are very trivial.

Numerical Aerodynamic Damping Evaluation of High-Pressure Steam Turbine Blades for Aeromechanical Characterization

2016 ◽  
Author(s):  
Lorenzo Peruzzi ◽  
Juri Bellucci ◽  
Lorenzo Pinelli ◽  
Andrea Arnone ◽  
Lorenzo Arcangeli ◽  
...  
Keyword(s):  
High Pressure ◽  
Steam Turbine ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Mechanical Coupling ◽  
High Pressure Steam ◽  
Aerodynamic Damping ◽  
Blade Row ◽  
Pressure Steam ◽  
Steam Turbine Blade

A validated non-linear uncoupled method for flutter stability analysis was employed to estimate the aerodynamic damping of an HP (High-Pressure) steam turbine blade row. Usually such blade rows are not affected to flutter instability problems, yet an estimation of the aerodynamic damping can be useful for an accurate aeromechanical characterization of these kind of blade rows. The geometry under investigation is a typical steam turbine blade row at design point. Computational aeroelastic analyses are performed on the more relevant modeshape, sampling the nodal diameters, in order to well describe the typical aeroelastic stability curve. The presence of the tip shroud implies a strong mechanical coupling between adjacent blades resulting in complex modeshapes with high frequency, significantly different from those usually analyzed in the flutter analysis. The results in term of aerodynamic damping curves are rather different from the usually sinusoidal shape. This is due to the large variation of the frequency over the analyzed nodal diameters, especially at low nodal diameters range. This results are useful to give a better insight in the aeroelastic response of this type of blades.

Study on High-Speed Milling of Steam Turbine Blade Materials - Differences in Cutting Characteristics of an Unforged Ingot and a Forged Part of Stainless Steel

2017 ◽  
Vol 749 ◽  
pp. 3-8
Author(s):  
Tomonori Kimura ◽  
Takekazu Sawa ◽  
Tatsuyuki Kamijyo
Keyword(s):  
Stainless Steel ◽  
Tool Wear ◽  
Steam Turbine ◽  
High Speed ◽  
Flank Wear ◽  
Turbine Blades ◽  
Cutting Speed ◽  
High Speed Milling ◽  
Finished Surface ◽  
Steam Turbine Blade

Stainless steel is an excellent material that has properties such as heat and corrosion resistance. Thus, stainless steel is used as a material in steam turbine blades. Steam turbine blades are mainly manufactured using two methods. One is the cutting of unforged metal ingots. Another is the cutting of forged parts. Small blades are made by cutting metal ingots. Large blades are made by cutting forged parts. The mechanical characteristics of a metal ingot and a forged part, such as hardness and toughness, are almost the same. There were not researches related to a relationship between “an unforged ingot and a forged part of stainless steel” and “the differences of the tool wear and the finished surface by high-speed milling”.In this study, the high-speed milling of stainless steel was attempted for high-efficiency cutting of a steam turbine blade. The differences of the tool wear and the finished surface in the cuttings of an unforged ingot and a forged part were investigated. In the experiment, the cutting tool was a TiAlN coating radius solid end mill made of cemented carbide. The diameter of the end mill was 5 mm, and the corner radius was 0.2 mm. The cutting speed were 100 m/min-600 m/min. The workpieces used were a metal ingot and a forged part of stainless steel. In the results, it was found that the differences of the tool wear and the finished surface in the cuttings of an unforged ingot and a forged part. In the case of the unforged ingot, the flank wear became large with increasing cutting speed. On the other hand, in the case of forged part, the flank wear rapidly increased at a cutting speed of 100 m/min. In addition, the flank wear became smaller than the cutting speed 100 m/min at the cutting speed 200 m/min. Further, the flank wear became large with increasing cutting speed at cutting speeds higher than 200 m/min. That is, the flank wear was at a minimum at a cutting speed of 200 m/min. Although it could not be confirmed the characteristic of high speed milling at an unforged ingot, it has been identified at a forged part.

Research on the Manufacturing of Steam Turbine Blade by Using Investment Casting Technology

2013 ◽  
Vol 789 ◽  
pp. 330-340 ◽  
Author(s):  
Hafid
Keyword(s):  
Steam Turbine ◽  
Turbine Blade ◽  
Investment Casting ◽  
Turbine Blades ◽  
Injection Pressure ◽  
Casting Process ◽  
Machining Process ◽  
Shape Accuracy ◽  
Casting Technology ◽  
Steam Turbine Blade

This paper presents the results of research on the manufacturing of steam turbine blade by using investment casting technology. Metal forming technology with precision casting process or investment casting is the right technology for the manufacture of turbine blades, because it can produce casting products that has advantages in size and shape accuracy, surface finish and the ability to produce thin casting, which the usually foundry can not be done. The purpose of this research is to produce a good quality of the casting products as an effort to reduce import dependency of steam turbine blade and to be the alternative way of making steam turbine blades in Indonesia, in addition to the machining process. Based on the experimentation trial implemented on casting products of stainless steel 304, the result indicates that the injection temperature for the wax NF-411 and optimal nozzle in hydraulic injection machine are 64°C and 30°C, injection pressure 1.75 MPa and injection time 9 seconds. The best casting induction furnace achieved at temperature 1,620°C as for to the number of ceramic mould coat which is good to be obtained at 7 layers. The testing results show that: (1) the chemical composition is appropriate with standard, (2) the hardness is 160 HB, (3) the shrinkage is 2.83%.

Reconstruction of a Steam Turbine Blade Using Piecewise Bernstein Polynomials and Transfinite Interpolation

2021 ◽  
Author(s):  
Luis David Pérez Rubio ◽  
Sergio Ricardo Galván González ◽  
Francisco Javier Domínguez Mota ◽  
Angel Cerriteño Sánchez ◽  
Miguel Angel Tamayo Soto ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Turbine Blade ◽  
Bernstein Polynomials ◽  
Turbine Blades ◽  
Maximum Efficiency ◽  
Spanwise Direction ◽  
Virtual Model ◽  
Cross Sectional ◽  
Transfinite Interpolation ◽  
Steam Turbine Blade

Abstract Turbine blades are designed to achieve its maximum efficiency, but deformations caused by the exposition to extreme operating environments provokes reduction in the engine performance. Often, operators choose to repair a damaged blade instead of replacing it to save money, however, reconstructing its virtual model, commonly the first step in the repairing process, can be challenging due to the geometrical complexity of the blades, variability in deformations and the requirement to meet the dimensions specified by the manufacturer. This paper presents the reconstruction methodology of the clean virtual model of a steam turbine blade through numerical tools, as a previous step for regenerating a worn blade. First, few cross-sectional airfoil profiles are extracted from the damaged blade and are regenerated using Bernstein polynomials; then, using the previously obtained data, many more profiles are interpolated and stacked along the spanwise direction of the blade via Transfinite Interpolation in order to obtain a smooth and continuous representation of the reference blade. Final deviation between the reference and reconstructed model resulted in an average value of 1.5496 × 10−3 % and 9.685 × 10−5 % relative to the rotor diameter in the pressure and suction sides respectively, showing an accuracy that could be considered to be used in industrial applications or optimization.

Pretwist and Shear Flexibility in the Vibrations of Turbine Blades

1985 ◽  
Vol 52 (2) ◽  
pp. 409-415 ◽  
Author(s):  
S. Krenk ◽  
O. Gunneskov
Keyword(s):  
Steam Turbine ◽  
Turbine Blade ◽  
Wall Thickness ◽  
Cross Sections ◽  
Strain Energy ◽  
Turbine Blades ◽  
Beam Element ◽  
Shear Stresses ◽  
Warping Function ◽  
Steam Turbine Blade

A theory is developed for pretwisted beams with finite shear flexibility. The effect of pretwist is accounted for via the axial derivative of the St. Venant warping function. The shear flexibility relies on a decomposition of the shear stresses into torsion and shear contributions, and the normalized strain energy of the latter is expressed in terms of the shear flexibility tensor. An explicit approximation for the shear flexibility tensor is derived for cross sections of moderate wall thickness. A special Legendre transformation is used to obtain a consistent discretization, which is then cast in the form of a finite beam element. The accuracy of the method is illustrated by comparison with experimental results for a steam turbine blade, and the effects of pretwist and shear flexibility are discussed.

Perioperative Skin Conditioning for Patients With Skin of Color

2021 ◽  
pp. 074880682198989
Author(s):  
Alix Ferdinand ◽  
Suzan Obagi
Keyword(s):  
Treatment Regimen ◽  
Skin Care ◽  
Practical Approach ◽  
Postoperative Phase ◽  
Upward Trend ◽  
Wide Range ◽  
Before And After

The interest in cosmetic procedures for patients with skin of color is on an upward trend. Globally, dyschromia and hyperpigmentation remain the most common disorders for which patients seek treatment. The goals of a perioperative skin conditioning program include allowing a broad range of patients to be treated regardless of skin phototypes, maximizing results, and reducing risk of complications such as post-inflammatory hyperpigmentation and managing post-inflammatory hyperpigmentation if it occurs. The purpose of this article is to highlight common pigmentation concerns among patients with skin of color, the topical agents used to combat these concerns, and a practical approach to creating an effective yet straightforward topical skin care regimen that can be used across a wide range of patient skin phototypes. Before and after photos of patients with a variety of pigmentation concerns are presented along with a description of the treatment regimen used to improve their conditions and to get their skin to a safer state prior to performing any office-based procedures. By understanding the main concerns of patients with skin of color, one can use a simple and effective skincare regimen to allow these patients to be more safely treated. An effective skincare regimen both prepares the skin prior to procedures and postoperatively to help minimize dyschromias in the postoperative phase.

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