Mechanical Design of Turbine Blades With Interlocking Tip Shrouds

Author(s):  
David F. Toler

Abstract In contrast to the substantial body of literature regarding turbine aerodynamics and performance, there is a virtual absence of literature on the mechanical design of turbine components. As a contribution to this discipline, this paper is intended to provide an overview of a systematic approach for the mechanical design of turbine blades with interlocking tip shrouds which will result in a near-optimum mechanical and aerodynamic design for an industrial gas turbine.

Author(s):  
Ivan McBean ◽  
Said Havakechian ◽  
Pierre-Alain Masserey

In steam turbine power plants, the appropriate design of the last stage blades is critical in determining the plant efficiency and reliability and competitiveness. A high level of technical expertise combined with many years of operating experience are required for the improvement of last stage designs that increases performance, without sacrificing mechanical reliability. This paper focuses on three main development areas that are key for the development of last stage blades, namely the aerodynamic design, the mechanical design and the validation process. The three different lengths of last stage blade (LSB) were developed of 41in, 45in and 49in (and a number of scaled variants). The aerodynamic design process involves 3D CFD and flow path analysis, considerations such as last stage blade flutter and water droplet erosion, and last stage guide design. The mechanical design includes finite element stress and dynamic analysis, appropriate selection of the blade material, the coupling of the LSB with the rotor and the design of the LSB snubber and shroud. Experimental measurements form a key part of the product validation, from both the mechanical reliability and performance points of view.


Author(s):  
Edson Batista da Silva ◽  
Marcelo Assato ◽  
Rosiane Cristina de Lima

Usually, the turbogenerators are designed to fire a specific fuel, depending on the project of these engines may be allowed the operation with other kinds of fuel compositions. However, it is necessary a careful evaluation of the operational behavior and performance of them due to conversion, for example, from natural gas to different low heating value fuels. Thus, this work describes strategies used to simulate the performance of a single shaft industrial gas turbine designed to operate with natural gas when firing low heating value fuel, such as biomass fuel from gasification process or blast furnace gas (BFG). Air bled from the compressor and variable compressor geometry have been used as key strategies by this paper. Off-design performance simulations at a variety of ambient temperature conditions are described. It was observed the necessity for recovering the surge margin; both techniques showed good solutions to achieve the same level of safe operation in relation to the original engine. Finally, a flammability limit analysis in terms of the equivalence ratio was done. This analysis has the objective of verifying if the combustor will operate using the low heating value fuel. For the most engine operation cases investigated, the values were inside from minimum and maximum equivalence ratio range.


Author(s):  
F. Carchedi ◽  
G. R. Wood

This paper describes the design and development of a 15-stage axial flow compressor for a −6MW industrial gas turbine. Detailed aspects of the aerodynamic design are presented together with rig test data for the complete characteristic including stage data. Predictions of spanwise flow distributions are compared with measured values for the front stages of the compressor. Variable stagger stator blading is used to control the position of the low speed surge line and the effects of the stagger changes are discussed.


1986 ◽  
Author(s):  
W. Tabakoff ◽  
A. Hamed

Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to provide the basis for calculating the erosion and performance deterioration of turbines using pulverized coal, an investigation is undertaken to determine the three dimensional particle trajectories in a two stage turbine. The solution takes into account the influence of the variation in the three dimensional flow field. The change in particle momentum due to their collision with the turbine blades and casings is modeled using empirical equations derived from experimental Laser Doppler Velocimetry (LDV) measurements. The results show the three dimensional trajectory characteristics of the solid particles relative to the turbine blades. The results also show that the particle distribution in the flow field are determined by particle-blade impacts. The results obtained from this study indicate the turbine blade locations which are subjected to more blade impacts and hence more erosion damage.


Author(s):  
Mattias Broddega˚rd ◽  
Christian Homma

Gas turbine blades are operating under very demanding conditions. In modern industrial gas turbines, the rotating blades and the guide vanes of the first stages are hollow to allow internal cooling. This means that there is a possibility of having crack initiation on the internal surface of the components. Due to the complex casting geometry, this type of defects is very difficult to detect with conventional nondestructive testing techniques such as ultrasonic and radiographic testing. Siemens has developed a new non-destructive testing technique based on acoustic thermography, SIEMAT. The test object is energized by an ultrasonic excitation device. Due to the vibrations, a very slight heating will develop at cracks in the test object. The local increase of temperature is captured by a highly sensitive IR camera. The SIEMAT technique is capable of detecting both surface-breaking and internal cracks, including cracks under coatings. The testing time is very short, and the IR sequences are recorded for subsequent analysis. A major advantage for service applications is that the technique is mostly sensitive to closed defects such as cracks, since open defects where no contact between the faces is present, for example pores and scratch marks, will not cause any heat generation. Siemens is currently implementing the SIEMAT technique for assessment of service-exposed turbine blades from medium size gas turbines, which are due for reconditioning. By being able to verify that no internal cracks are present, the reliability of the reconditioned blades will be increased. This paper describes the SIEMAT testing technique, and the results obtained when applied on service-exposed industrial gas turbine blades.


Author(s):  
Alexander Wiedermann ◽  
Dirk Frank ◽  
Ulrich Orth ◽  
Markus Beukenberg

Test rig results and their comparison with computational analyses of a highly-loaded 11-stage compressor for a newly developed industrial gas turbine will be presented in this paper. The scope of the tests has been validation of aerodynamic and mechanical features of the bladed flow path to meet both the demands for single- and dual-shaft operation of the gas turbine. The test was carried out in three phases using extensive instrumentation. In phase 1 the front stages have been tested, and in phase 2 the test of the full 11-stage compressor was performed including numerous aerodynamic and structural check-outs. Vane and blade vibration modes were measured in all rows with numerous strain gauges using a telemetry system and Tip Timing, which additionally was applied to the front stage rotors. Concerning the mechanical design, finite element predictions of the vibration modes of all blades and vanes were carried out in the design phase to guarantee safe and resonance-free operation for a wide range of operational speeds which could be verified by the test data up to higher modes. Flow field computations were carried out with both a through flow solver and full 3-D viscous multistage solver based on Denton’s TBLOCK, where all rotor and stator flow fields had been solved simultaneously and compared with experiments. The effects of tip clearance and stator cavities on compressor performance have been taken into account by the computational analysis. Effects of inlet distortion were examined in phase 3. Comprehensive comparisons of computed and measured results will be presented. The extensive instrumentation gave also insight into flow details as vane pressure distributions and total pressure profiles in span wise direction. It will be shown that the agreements of predicted and measured data were excellent.


Author(s):  
S. J. Gill ◽  
M. D. Ingallinera ◽  
A. G. Sheard

The continuing development of industrial gas turbines is resulting in machines of increasing power and efficiency. The need to continue this trend is focusing attention on minimizing all loss mechanisms within the machine, including those associated with turbine blade tip clearance. In order to study tip clearance in the turbine, real time measurement is required of clearance between turbine blades and the casing in which they run. This measurement is not routinely performed, due to the harsh nature of the turbine environment. On those occasions when turbine tip clearance is measured, it is typically in development vehicles, often using cooled probes that are somewhat unsuitable for use in production gas turbines. In this paper a program of work is reported that was undertaken with the purpose of identifying a promising turbine tip clearance measurement system that used the capacitive gap measurement technique. Issues surrounding the application of three systems to the turbine section of a GE MS6001FA gas turbine are identified and reported. Performance of the three evaluated systems is analyzed.


2016 ◽  
Vol 92 ◽  
pp. 262-271 ◽  
Author(s):  
D. Holländer ◽  
D. Kulawinski ◽  
A. Weidner ◽  
M. Thiele ◽  
H. Biermann ◽  
...  

Author(s):  
Digvijay B. Kulshreshtha ◽  
S. A. Channiwala ◽  
Jatin R. Patel

The combustion chamber of gas turbine unit is one of the most critical components to be designed. The study of literature review reveals that much work is available pertaining to design and performance of combustion chamber. However, the systematic approach and optimized liner wall configuration is not easily traceable in the literature. This is particularly true for small capacity units. Hence there is a need for experimental optimization of combustion chamber in small capacity range. The present work aims at the experimental optimization of liner wall configuration. Four different types of combustion chambers with primary zone equivalence ratios of 0.5, 0.7, 0.9 and 1.1 are designed, developed and experimented based on which an optimal configuration is recommended. It is worth to mention that the present work clearly focuses the combustion chamber with equivalence ratio in primary zone as 0.9 as the optimal combustion chamber.


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