The Experts below are selected from a list of 5583 Experts worldwide ranked by ideXlab platform

Dipak K. Sarkar - One of the best experts on this subject based on the ideXlab platform.

  • steam air blowing of main steam cold reheat hot reheat and other steam pipe lines
    Thermal Power Plant#R##N#Pre-Operational Activities, 2017
    Co-Authors: Dipak K. Sarkar
    Abstract:

    Steam turbine performances are greatly affected by the presence of any debris in main steam and reheat steam. Impingement of suspended particles on turbine Blades may lead to Blade Failure. “Steam” or “compressed air” is used to blow-out various steam pipe lines to remove rust, mill scales, loose pieces of scales, welding slag left over in pipe lines. Two different methods—“continuous blowing” and “puffing,” are used in blowing of steam pipe lines. Disturbance effect, K , of any suspended particulate matter during blowing must be greater than the disturbance effect experienced by the particle under BMCR. Value of K should be about 1.3–1.6 during steam blowing and 1.2–1.3 during compressed air blowing. Completion of blowing-out process is assessed by the degree of indentation made on target plates.

  • Steam/Air Blowing of Main Steam, Cold Reheat, Hot Reheat and Other Steam Pipe Lines
    Thermal Power Plant, 2017
    Co-Authors: Dipak K. Sarkar
    Abstract:

    Steam turbine performances are greatly affected by the presence of any debris in main steam and reheat steam. Impingement of suspended particles on turbine Blades may lead to Blade Failure. “Steam” or “compressed air” is used to blow-out various steam pipe lines to remove rust, mill scales, loose pieces of scales, welding slag left over in pipe lines. Two different methods—“continuous blowing” and “puffing,” are used in blowing of steam pipe lines. Disturbance effect, K , of any suspended particulate matter during blowing must be greater than the disturbance effect experienced by the particle under BMCR. Value of K should be about 1.3–1.6 during steam blowing and 1.2–1.3 during compressed air blowing. Completion of blowing-out process is assessed by the degree of indentation made on target plates.

R. K. Mishra - One of the best experts on this subject based on the ideXlab platform.

  • Failure Analysis of High-Pressure Compressor Blade in an Aero Gas Turbine Engine
    Journal of Failure Analysis and Prevention, 2018
    Co-Authors: R. K. Mishra, Vaishakhi Nandi, R. Raghavendra Bhat
    Abstract:

    Failure of high-pressure compressor rotor Blade in an aero gas turbine engine is analyzed to determine its root cause. Forensic and metallurgical investigations are carried out on the Blade and failed parts. The Failure of the platform ladder is found to the first in the chain of events that led to the compressor Blade Failure. The mode of Failure in the Blade is found to be fatigue and has originated from the damaged region on the leading edge caused by dislodgement of platform ladder. The Failure has caused extensive damages in high-pressure compressor module and also in downstream turbine Blades as a secondary effect.

  • Failure analysis of an un cooled turbine Blade in an aero gas turbine engine
    Engineering Failure Analysis, 2017
    Co-Authors: R. K. Mishra, Vaishakhi Nandi, Johny Thomas, K. Srinivasan, R. Raghavendra Bhatt
    Abstract:

    Abstract Failure of an un-cooled turbine Blade in an aero gas turbine engine is analyzed to determine its root cause. The operational condition of the engine was studied and metallurgical investigations are carried out on the fractured Blade. The Failure has originated from the leading edge and has propagated towards the trailing edge. Thermal cracks due to surface oxidation leading to fatigue were found to be the cause of the Blade Failure. Operation at elevated temperatures due to malfunction of sensors in the engine control system was found responsible for initiating the thermal cracks.

  • Investigation of HP Turbine Blade Failure in a Military Turbofan Engine
    International Journal of Turbo & Jet-Engines, 2017
    Co-Authors: R. K. Mishra, Vaishakhi Nandi, Johny Thomas, K. Srinivasan, R. Raghavendra Bhatt
    Abstract:

    AbstractFailure of a high pressure (HP) turbine Blade in a military turbofan engine is investigated to determine the root cause of Failure. Forensic and metallurgical investigations are carried out on the affected Blades. The loss of coating and the presence of heavily oxidized intergranular fracture features including substrate material aging and airfoil curling in the trailing edge of a representative Blade indicate that the coating is not providing adequate oxidation protection and the Blade material substrate is not suitable for the application at hand. Coating spallation followed by substrate oxidation and aging leading to intergranular cracking and localized trailing edge curling is the root cause of the Blade Failure. The remaining portion of the Blade fracture surface showed ductile overload features in the final Failure. The damage observed in downstream components is due to secondary effects.

  • Failure of Low-Pressure Turbine Blades in Military Turbofan Engines: Causes and Remedies
    Journal of Failure Analysis and Prevention, 2016
    Co-Authors: R. K. Mishra, K. Srinivasan
    Abstract:

    Failure of low-pressure (LP) turbine rotor Blades in low bypass military turbofan engines is a great concern for designers, manufactures, repair and overhaul agencies, operators, and airworthiness authorities. The present paper analyzes the LP turbine Blade Failure cases to determine its root cause. Forensic and metallurgical investigations are carried out on the failed Blades. In most cases, the Failure was originated from the leading edge and had propagated toward the trailing edge. Intergranular features and high oxidation on the fractured surface have been found as the cause of fatigue Failure. Operation at elevated temperatures for considerable time was found responsible for these fatigue Failures. Malfunction of fuel system, Failure in control sensors, and nonuniformity in atomizer characteristics were the root cause of high temperature in turbine leading to the Failure of Blades. The paper also presents various remedial measures to address the Blade Failures from manufacturing and operational points of view.

  • Investigation of LP Turbine Blade Failure in a Low Bypass Turbofan Engine
    Journal of Failure Analysis and Prevention, 2014
    Co-Authors: R. K. Mishra, K. Srinivasan, Johney Thomas, Nandi Vaishakhi, Raghavendra R. Bhat
    Abstract:

    Failure of low pressure turbine rotor Blade in a low bypass turbofan engine is analyzed to determine its root cause. Forensic and metallurgical investigations are carried out on the Blade failed. The Failure has originated from the leading edge and has propagated towards the trailing edge. Intergranular features and high oxidation on the fractured surface are the cause of Failure which is probably due to creep-stress rupture. This Failure has caused extensive damages in low pressure turbine module and also in downstream modules as a secondary effect. Remedial measures are also suggested to prevent such Failures.

Dražan Kozak - One of the best experts on this subject based on the ideXlab platform.

  • Steam turbine moving Blade Failure caused by corrosion fatigue – case history
    Procedia Structural Integrity, 2018
    Co-Authors: Marko Katinić, Dražan Kozak
    Abstract:

    Abstract Corrosion fatigue has been identified as one of the leading causes of steam turbine rotor Blades Failure. Despite of numerous research and development in the area of preventing sudden rotor Blades Failure due to corrosion fatigue, in the practice these Failures continue to occur. This paper just describes one of number historical cases of rotor Blade fracture that was caused by corrosion fatigue. It was an industrial turbine installed in fertilizer production plant Petrokemija Kutina, Croatia. The broken Blades were belonged to the turbine stage located in the phase transition zone (salt zone) of the turbine. The paper also describes the analysis of the Failure cause and the modification of the turbine stage that was failed.

  • steam turbine moving Blade Failure caused by corrosion fatigue case history
    Procedia structural integrity, 2018
    Co-Authors: Marko Katinic, Dražan Kozak
    Abstract:

    Abstract Corrosion fatigue has been identified as one of the leading causes of steam turbine rotor Blades Failure. Despite of numerous research and development in the area of preventing sudden rotor Blades Failure due to corrosion fatigue, in the practice these Failures continue to occur. This paper just describes one of number historical cases of rotor Blade fracture that was caused by corrosion fatigue. It was an industrial turbine installed in fertilizer production plant Petrokemija Kutina, Croatia. The broken Blades were belonged to the turbine stage located in the phase transition zone (salt zone) of the turbine. The paper also describes the analysis of the Failure cause and the modification of the turbine stage that was failed.

Xiao Chen - One of the best experts on this subject based on the ideXlab platform.

  • preliminary Failure investigation of a 52 3 m glass epoxy composite wind turbine Blade
    Engineering Failure Analysis, 2014
    Co-Authors: Xiao Chen, Wei Zhao, Xiao Lu Zhao
    Abstract:

    Abstract Despite the enthusiastic pursuing for large wind turbine Blades to reduce the cost of wind power, wind energy industry has witnessed a number of catastrophic Blade Failure accidents in recent years. In order to provide more insights into the Failure of large Blades, this short communication presents preliminary investigation on a 52.3 m composite Blade designed for multi-megawatt wind turbines. Static loads were applied to simulate extreme load conditions subjected by the Blade. After Blade Failure, visual inspection was carried out and Failure characteristics of the Blade were examined. It was found that the Blade exhibited multiple Failure modes. Among various Failure modes observed, delamination of unidirectional laminates in the spar cap was identified to be the plausible root cause of the catastrophic Failure of the Blade. This study emphasized that through-thickness stresses can significantly affect the Failure of large composite Blades and provided some suggestions to the current design practices.

  • Failure test and finite element simulation of a large wind turbine composite Blade under static loading
    Energies, 2014
    Co-Authors: Xiao Chen, Wei Zhao, Xiao Lu Zhao, Jianzhong Xu
    Abstract:

    This study presented a Failure analysis of a 52.3 m composite wind turbine Blade under static loading. Complex Failure characteristics exhibited at the transition region of the Blade were thoroughly examined and typical Failure modes were indentified. In order to predict multiple Failure modes observed in the tests and gain more insights into the Failure mechanisms of the Blade, a Finite Element (FE) simulation was performed using a global-local modeling approach and Progressive Failure Analysis (PFA) techniques which took into account material Failure and property degradation. Failure process and Failure characteristics of the transition region were satisfactorily reproduced in the simulation, and it was found that accumulated delamination in spar cap and shear web Failure at the transition region were the main reasons for the Blade to collapse. Local buckling played an important role in the Failure process by increasing local out-of-plane deformation, while the Brazier effect was found not to be responsible for the Blade Failure.

  • Preliminary Failure investigation of a 52.3 m glass/epoxy composite wind turbine Blade
    Engineering Failure Analysis, 2014
    Co-Authors: Xiao Chen, Wei Zhao, Xiao Lu Zhao
    Abstract:

    Abstract Despite the enthusiastic pursuing for large wind turbine Blades to reduce the cost of wind power, wind energy industry has witnessed a number of catastrophic Blade Failure accidents in recent years. In order to provide more insights into the Failure of large Blades, this short communication presents preliminary investigation on a 52.3 m composite Blade designed for multi-megawatt wind turbines. Static loads were applied to simulate extreme load conditions subjected by the Blade. After Blade Failure, visual inspection was carried out and Failure characteristics of the Blade were examined. It was found that the Blade exhibited multiple Failure modes. Among various Failure modes observed, delamination of unidirectional laminates in the spar cap was identified to be the plausible root cause of the catastrophic Failure of the Blade. This study emphasized that through-thickness stresses can significantly affect the Failure of large composite Blades and provided some suggestions to the current design practices.

Xiao Lu Zhao - One of the best experts on this subject based on the ideXlab platform.

  • preliminary Failure investigation of a 52 3 m glass epoxy composite wind turbine Blade
    Engineering Failure Analysis, 2014
    Co-Authors: Xiao Chen, Wei Zhao, Xiao Lu Zhao
    Abstract:

    Abstract Despite the enthusiastic pursuing for large wind turbine Blades to reduce the cost of wind power, wind energy industry has witnessed a number of catastrophic Blade Failure accidents in recent years. In order to provide more insights into the Failure of large Blades, this short communication presents preliminary investigation on a 52.3 m composite Blade designed for multi-megawatt wind turbines. Static loads were applied to simulate extreme load conditions subjected by the Blade. After Blade Failure, visual inspection was carried out and Failure characteristics of the Blade were examined. It was found that the Blade exhibited multiple Failure modes. Among various Failure modes observed, delamination of unidirectional laminates in the spar cap was identified to be the plausible root cause of the catastrophic Failure of the Blade. This study emphasized that through-thickness stresses can significantly affect the Failure of large composite Blades and provided some suggestions to the current design practices.

  • Failure test and finite element simulation of a large wind turbine composite Blade under static loading
    Energies, 2014
    Co-Authors: Xiao Chen, Wei Zhao, Xiao Lu Zhao, Jianzhong Xu
    Abstract:

    This study presented a Failure analysis of a 52.3 m composite wind turbine Blade under static loading. Complex Failure characteristics exhibited at the transition region of the Blade were thoroughly examined and typical Failure modes were indentified. In order to predict multiple Failure modes observed in the tests and gain more insights into the Failure mechanisms of the Blade, a Finite Element (FE) simulation was performed using a global-local modeling approach and Progressive Failure Analysis (PFA) techniques which took into account material Failure and property degradation. Failure process and Failure characteristics of the transition region were satisfactorily reproduced in the simulation, and it was found that accumulated delamination in spar cap and shear web Failure at the transition region were the main reasons for the Blade to collapse. Local buckling played an important role in the Failure process by increasing local out-of-plane deformation, while the Brazier effect was found not to be responsible for the Blade Failure.

  • Preliminary Failure investigation of a 52.3 m glass/epoxy composite wind turbine Blade
    Engineering Failure Analysis, 2014
    Co-Authors: Xiao Chen, Wei Zhao, Xiao Lu Zhao
    Abstract:

    Abstract Despite the enthusiastic pursuing for large wind turbine Blades to reduce the cost of wind power, wind energy industry has witnessed a number of catastrophic Blade Failure accidents in recent years. In order to provide more insights into the Failure of large Blades, this short communication presents preliminary investigation on a 52.3 m composite Blade designed for multi-megawatt wind turbines. Static loads were applied to simulate extreme load conditions subjected by the Blade. After Blade Failure, visual inspection was carried out and Failure characteristics of the Blade were examined. It was found that the Blade exhibited multiple Failure modes. Among various Failure modes observed, delamination of unidirectional laminates in the spar cap was identified to be the plausible root cause of the catastrophic Failure of the Blade. This study emphasized that through-thickness stresses can significantly affect the Failure of large composite Blades and provided some suggestions to the current design practices.