Life Augmentation of Turbine Exhaust System Compensators Through Integrated MADM Optimization Approach of Stress Based Fatigue Cycles

2021 ◽  
Author(s):  
Nitin D. Pagar ◽  
Amit R. Patil
Keyword(s):  
Exhaust System ◽  
Optimization Methods ◽  
Fractional Factorial ◽  
Design Parameters ◽  
Optimization Approach ◽  
Auxiliary Equipment ◽  
Maximum Expansion ◽  
Optimal Configurations ◽  
Selection Of ◽  
Turbine Exhaust

Abstract Exhaust expansion joints, also known as compensators, are found in a variety of applications such as gas turbine exhaust pipes, generators, marine propulsion systems, OEM engines, power units, and auxiliary equipment. The motion compensators employed must have accomplished the maximum expansion-contraction cycle life while imposing the least amount of stress. Discrepancies in the selecting of bellows expansion joint design parameters are corrected by evaluating stress-based fatigue life, which is challenging owing to the complicated form of convolutions. Meridional and circumferential convolution stress equations that influencing fatigue cycles are evaluated and verified with FEA. Fractional factorial Taguchi L25 matrix is used for finding the optimal configurations. The discrete design parameters for the selection of the suitable configuration of the compensators are analysed with the help of the MADM decision making techniques. The multi-response optimization methods GRA, AHP, and TOPSIS are used to determine the parametric selection on a priority basis. It is seen that weighing distribution among the responses plays an important role in these methods and GRA method integrated with principal components shows best optimal configurations. Multiple regression technique applied to these methods also shows that PCA-GRA gives better alternate solutions for the designer unlike the AHP and TOPSIS method. However, higher ranked Taguchi run obtained in these methods may enhance the suitable selection of different design configurations. Obtained PCA-GRG values by Taguchi, Regression and DOE are well matched and verified for the all alternate solutions. Further, it also shows that stress based fatigue cycles obtained in this analysis for the L25 run indicates the range varying from 1.13 × 104 cycles to 9.08 × 105 cycles, which is within 106 cycles. This work will assist the design engineer for selecting the discrete parameters of stiff compensators utilized in power plant thermal appliances.

Optimal Offloading Configuration of Spread-Moored FPSOs

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Steven M. Wilkerson ◽  
Satish Nagarajaiah
Keyword(s):  
Environmental Conditions ◽  
Main Tool ◽  
Design Parameters ◽  
Optimization Approach ◽  
Analysis Model ◽  
Simple Analysis ◽  
Formal Approach ◽  
Fine Tune ◽  
Formal Optimization ◽  
Selection Of

As the oil offloading operations of floating production storage and offloading (FPSO) units become more routine, the desire grows to increase the availability for offloading and thus decrease production downtime. Experience with these operations is the main tool available to increase the efficiency of this aspect of deepwater production. However, it is clear that a formal optimization approach can help to fine tune design parameters so that not only is availability increased but the significance of each design parameter can be better understood. The key issue is to define the environmental conditions under which the vessels involved in offloading are able to maintain position. By this, we reduce the notion of availability to a set of operating criteria, which can or cannot be met for a particular set of environmental conditions. The actual operating criteria such as relative vessel heading depend on selection of design parameters, such as the direction and magnitude of external force applied by thrusters or tugs. In the earliest offloading operations, engineering judgment was used to determine the feasibility of offloading at a particular time. For example, if wind and current were not expected to exceed a 1year return period, offloading may be considered safe. This approach can be both conservative and unconservative, depending on the nuances of the particular environmental conditions. This study will propose a formal approach to choosing the design parameters that optimize the availability of a FPSO for offloading. A simple analysis model will be employed so that optimization can be performed quickly using a robust second order method. The proposed analysis model will be compared to model test data to demonstrate its agreement with the more complex system.

A Study on Parameter Determination Method of Large-Scale and Complex Dynamic Systems With Judgment Functions (No. 1)—Theory

1983 ◽  
Vol 105 (2) ◽  
pp. 64-69
Author(s):  
Osamu Furukawa ◽  
Hideomi Ikeshoji ◽  
Satoshi Iida
Keyword(s):  
Dynamic Systems ◽  
Large Scale ◽  
Optimization Methods ◽  
Approximate Model ◽  
Difficult Problem ◽  
Parameter Determination ◽  
Design Parameters ◽  
Dynamic Relationships ◽  
Complex Mechanical Systems ◽  
Selection Of

In the design of large-scale and complex mechanical systems, determination of design parameters is a very difficult problem. This study deals with parameter satisfaction problems of large-scale, complex, and dynamic systems with judgment functions. In order to solve these problems, a new method is proposed which sequentially exchanges the original mathematical model to an analyzable approximate model by means of the identification method and which improves a lot of parameters simultaneously. First, criteria of selection of attributes to build up approximate model are clarified. Moreover, as tools for selection of attributes, two analysis charts are proposed which express dynamic relationships among the attributes. Second, a general condition to determine the structure of approximate models and a statistical method to linearize the original model with judgment functions are derived. Finally, a combinatorial method of statistical identification and parameter optimization methods are proposed. By this method, some shortcomings of sensitivity analysis, decomposition technique (enormous calculations of partial derivatives) and statistical methods such as Monte Carlo method (bad convergency of solutions) can be avoided. As a result of this, it becomes possible to search satisfactory parameters efficiently.

Integration of an Automatic Optimizer Functionality Into the Design Process of Industrial Steam Turbines

2012 ◽  
Author(s):  
Dimitri Drapkin ◽  
Franz Kores ◽  
Thomas Polklas
Keyword(s):  
Design Process ◽  
Optimization Methods ◽  
Simultaneous Optimization ◽  
Design Parameters ◽  
Optimization Approach ◽  
Steam Turbines ◽  
Particle Swarm Optimizer ◽  
Optimization Task ◽  
Wide Range ◽  
Optimization Parameters

Industrial steam turbines are mostly tailor made machinery, varying in a wide range of specifications. This feature introduces high requirements on the design process which has to be flexible, efficient and fast at the same time. Given live steam and design parameters as input, the geometry corresponding to the valid design scheme can be calculated together with the required thermodynamic, aerodynamic and mechanical characteristics. By variation of design parameters a design may be achieved which optimizes both, efficiency and cost. The optimization task is formulated mathematically, e.g. crucial optimization parameters, criteria for evaluation of different designs and other required constraints are selected. The structure of the resulting optimization problem is analyzed. Based on this analysis a modular optimization system design is proposed. The choice of Genetic Algorithms and Adaptive Particle Swarm Optimizer as optimization methods is discussed, recommendations for their proper use are given. A bicriterial optimization approach for a simultaneous optimization of efficiency and cost is developed.

Aerodynamic Design and Experimental Study of Marine Gas Turbine Exhaust Volutes

1981 ◽  
Author(s):  
Lu Xingsu ◽  
Pan Kunyuan ◽  
Wu Zuomin
Keyword(s):  
Gas Turbine ◽  
Exhaust System ◽  
Aerodynamic Characteristics ◽  
Basic Design ◽  
Aerodynamic Design ◽  
Engine Room ◽  
Annular Diffuser ◽  
Gas Turbine Exhaust ◽  
Selection Of ◽  
Turbine Exhaust

The aerodynamic characteristics of the exhaust system have an important bearing on the economic aspects of the marine gas turbine. The exhaust volute is an important component of the exhaust system. The design of turbine exhaust volutes must take into account the structural demands of the gas turbine, the layout of the exhaust system as a whole in the engine room and the hull as well as its overall dimension requirements. This paper discusses the design principles of exhaust volutes. Given the hub-tip ratio dl/D1 of turbine exit (volute entry), a method is developed to rationally select the axial length L and radial width B. The selection of an annular diffuser and the relevant parameters along with the coordination of diffuser and collector are analyzed. On the basis of an analysis of experimental data the basic design criteria of exhaust volutes are proposed.

Effiecency criterion for selection of design parameters of aerospace system

2016 ◽  
Vol 22 (2(99)) ◽  
pp. 48-51
Author(s):  
D.S. Kalynychenko ◽  
◽  
Ye.Yu. Baranov ◽  
M.V. Poluian ◽  
◽  
...  
Keyword(s):  
Design Parameters ◽  
Selection Of

scholarly journals Heuristic Optimization of Overloading Due to Electric Vehicles in a Low Voltage Grid

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6069
Author(s):  
Sajjad Haider ◽  
Peter Schegner
Keyword(s):  
Electric Vehicles ◽  
Low Voltage ◽  
Optimization Methods ◽  
Monte Carlo Analysis ◽  
Heuristic Optimization ◽  
Optimization Approach ◽  
Worst Case ◽  
Voltage Drops ◽  
The Individual ◽  
Nodal Voltage

It is important to understand the effect of increasing electric vehicles (EV) penetrations on the existing electricity transmission infrastructure and to find ways to mitigate it. While, the easiest solution is to opt for equipment upgrades, the potential for reducing overloading, in terms of voltage drops, and line loading by way of optimization of the locations at which EVs can charge, is significant. To investigate this, a heuristic optimization approach is proposed to optimize EV charging locations within one feeder, while minimizing nodal voltage drops, cable loading and overall cable losses. The optimization approach is compared to typical unoptimized results of a monte-carlo analysis. The results show a reduction in peak line loading in a typical benchmark 0.4 kV by up to 10%. Further results show an increase in voltage available at different nodes by up to 7 V in the worst case and 1.5 V on average. Optimization for a reduction in transmission losses shows insignificant savings for subsequent simulation. These optimization methods may allow for the introduction of spatial pricing across multiple nodes within a low voltage network, to allow for an electricity price for EVs independent of temporal pricing models already in place, to reflect the individual impact of EVs charging at different nodes across the network.

scholarly journals Impact of Cross-Tie Properties on the Modal Behavior of Cable Networks on Cable-Stayed Bridges

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Javaid Ahmad ◽  
Shaohong Cheng ◽  
Faouzi Ghrib
Keyword(s):  
Analytical Model ◽  
Design Parameters ◽  
Reference Base ◽  
Cable Network ◽  
Cable Networks ◽  
Modal Behavior ◽  
Stiffness And Damping ◽  
Main Cables ◽  
The Impact ◽  
Selection Of

Dynamic behaviour of cable networks is highly dependent on the installation location, stiffness, and damping of cross-ties. Thus, these are the important design parameters for a cable network. While the effects of the former two on the network response have been investigated to some extent in the past, the impact of cross-tie damping has rarely been addressed. To comprehend our knowledge of mechanics associated with cable networks, in the current study, an analytical model of a cable network will be proposed by taking into account both cross-tie stiffness and damping. In addition, the damping property of main cables in the network will also be considered in the formulation. This would allow exploring not only the effectiveness of a cross-tie design on enhancing the in-plane stiffness of a constituted cable network, but also its energy dissipation capacity. The proposed analytical model will be applied to networks with different configurations. The influence of cross-tie stiffness and damping on the modal response of various types of networks will be investigated by using the corresponding undamped rigid cross-tie network as a reference base. Results will provide valuable information on the selection of cross-tie properties to achieve more effective cable vibration control.

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