Application of structural modification method to nonlinear vibration analysis of bladed disks

Download
2013
Şayin, Burcu
High cycle fatigue failure of turbine blades is one of the most important problems in the design of gas turbine engines; hence, bladed-disk assemblies have been studied extensively for more than half a century. Damping design becomes an important issue in order to attenuate the blade vibration. For bladed-disk systems, friction damping concept is a common strategy to decrease vibration levels. There are different strategies in order to add friction damping to the system: blade-to-blade dampers such as shrouds and underplatform dampers such as wedge dampers. In the design of friction dampers, geometry of the friction contact becomes an important issue for maximizing energy dissipation. In order to determine the optimum damper geometry, i.e. shroud angle for shroud contacts and wedge surface angles for wedge dampers, nonlinear forced response analysis should be repeated by changing the finite element models in order to incorporate these geometry changes. Repeating the finite element analysis for each geometry change requires significant amount of time in the case of large finite element models used in real life examples. Moreover, in order to accurately model frictional contacts, high number of friction elements are required and utilizing modal superposition approach the number of nonlinear equations can be decreased significantly compared to receptance methods. Therefore, in this thesis, in order to decrease the computational time required for the finite element analysis, a new structural modification method with additional degrees of freedom is developed. The developed method is capable of determining the modal data of the modified structure by using modal data of the original structure and system matrices of the modifying part. The developed structural modification method is compared with the available modification methods in terms of computational time required and it is observed that the developed modification method is computationally more efficient than the existing methods. As a case study, bladed disk systems with integrally inserted shrouds are studied. Using the developed structural modification method and the nonlinear forced response prediction method, the effect of change of shroud angle is studied.

Suggestions

Validation of MISES 2 D Boundary Layer Code for High Pressure Turbine Aerodynamic Design
ANDREW, PHILIP; Kahveci, Harika Senem (2007-01-01)
Avoiding aerodynamic separation and excessive shock losses in gas turbine turbomachinery components can reduce fuel usage, and thus reduce operating cost. In order to achieve this, blading designs should be made robust to a wide range of operating conditions. Consequently, a design tool is needed which can be executed quickly for each of many operating conditions, and on each of several design sections which will accurately capture loss, turning and loading. This paper presents the validation of a boundary ...
Validation of MISES Two-Dimensional Boundary Layer Code for High-Pressure Turbine Aerodynamic Design
ANDREW, PHILIP; Kahveci, Harika Senem (ASME International, 2009-07-01)
Avoiding aerodynamic separation and excessive shock losses in gas turbine turbomachinery components can reduce fuel usage and thus reduce operating cost. In order to achieve this, blading designs should be made robust to a wide range of operating conditions. Consequently, a design tool is needed-one that can be executed quickly for each of many operating conditions and on each of several design sections, which will accurately capture loss, turning, and loading. This paper presents the validation of a bounda...
APPLICATION OF A FUZZY LOGIC CONTROLLER FOR SPEED CONTROL ON A SMALL-SCALE TURBOJET ENGINE
Usenmez, Serdar; Ekinci, Sinan; Uzol, Oğuz; Yavrucuk, İlkay (2014-06-20)
Having a small-scale turbojet engine operate at a desired speed with minimum steady state error, while maintaining good transient response is crucial in many applications, such as UAVs, and requires precise control of the fuel flow.
Comparison of different aspect ratio cooling channel designs for a liquid propellant rocket engine
Boysan, M. E.; Ulaş, Abdullah; Toker, K. A.; Seckin, B. (2007-06-16)
High combustion temperatures and long operation durations require the use of cooling techniques in liquid propellant rocket engines. For high-pressure and high-thrust rocket engines with long operation times, regenerative cooling is the most preferred cooling method. In regenerative cooling, a coolant flows through passages formed either by constructing the chamber liner from tubes or by milling channels in a solid liner. Traditionally, approximately square cross sectional channels have been used. However, ...
Experimental Investigation of Viscous Flow Normal to NACA 0012 Airfoil at low Reynolds Numbers
Gunaydınoglu, Erkan; Kurtuluş, Dilek Funda (null; 2018-07-11)
The low Reynolds number aerodynamics at high angle of attack is crucial for the design of unmanned aerial vehicles and wind turbine blades. The current study aims to enhance the insight on the near wake of airfoils normal to free stream. The near wake structure on a NACA 0012 airfoil normal to free-stream is measured with particle image velocimetry in the range of Reynolds number 7000 to 20000. The velocity and vorticity fields of the wake structures are studied and further analysis with Proper Orthogonal D...
Citation Formats
B. Şayin, “Application of structural modification method to nonlinear vibration analysis of bladed disks,” M.S. - Master of Science, Middle East Technical University, 2013.