Three-dimensional modelling of impulse forces and torques on a gas turbine blade due to nozzle excitations

Agarwal, Sunil (1995) Three-dimensional modelling of impulse forces and torques on a gas turbine blade due to nozzle excitations. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (15MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

The efficiency of turbines depends to a large extent on the forces developed on rotor blades. The blades, while they pass by nozzles, are subjected to gas forces. It is quite important to understand the development of these forces to do any useful turbomachine work. The understanding of these forces and torques would also be quite helpful in designing the bearing supports. -- The rotor as well as the nozzle system can be defined in an inertial frame at any instant of time. In this frame, the fluid-flow through the nozzles can be described as a vector in three dimensions. Similarly, the position and the velocity of any point on the rotor blade can also be specified at any instant of time. Using transformation matrices, one can calculate the change in momentum of gases as they impinge on the blade surfaces and get reflected. The resulting forces, then, can be expressed in the inertial frame, and one can calculate the three-dimensional forces and torques. -- The thesis brings forth an analytical model to calculate the impulse forces, and the resulting torques on the rotating blade due to nozzle excitations. The results obtained by the present method are compared with those used by conventional method to establish the validity of the model and the underlying principle. The modelling principle is quite general in nature and can be used for various rotating machines.

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