Gas Turbine Axial Thrust Control via Annular Cavity
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Solution Overview
Problem
Existing gas turbine designs face challenges in balancing axial thrust, leading to increased load on thrust bearings, vibrations, and inefficiencies due to the lack of control over axial thrust, especially during load changes and modifications.
Innovation Solution
A method is introduced to configure the gas turbine so that it generates a negative thrust at no-load and low partial load, transitioning to positive thrust at high loads, using a controlled additional thrust applied through an annular cavity system without consuming compressed air, utilizing existing structural components and minimizing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a pressure balance piston is used to balance axial thrust, then the load on the thrust bearing is reduced, but additional structural components and compressed air consumption are required
Solution Approach 1:
The invention extracts the thrust balancing function from separate structural components (pressure balance piston, balance chamber) and integrates it into the existing annular passage system. The axial force is balanced by utilizing the pressure differential across the turbine rotor in the annular passage, eliminating the need for additional balance pistons and associated structural elements.
Solution Approach 2:
The annular passage serves multiple functions: it guides cooling air from the compressor to the turbine rotor, and simultaneously provides the mechanism for axial thrust balancing. By making the cooling air flow path serve dual purposes, the invention eliminates the need for separate dedicated components for thrust balance.
2Force
If a pressure balance piston is used to balance axial thrust, then the load on the thrust bearing is reduced, but compressed air is lost through seals or requires considerable pressure level
Solution Approach 1:
The system uses the existing cooling air flow and pressure differential to achieve thrust balancing without requiring additional compressed air supply. The cooling air that would otherwise be wasted or require high pressure is instead utilized to create the balancing force, making the system self-sufficient regarding air consumption.
3Device complexity
If the axial thrust is not controlled, then the gas turbine structure remains simple, but thrust reversal and increased vibrations occur during load changes
Solution Approach 1:
The invention implements dynamic thrust balancing by controlling the opening degree of the first opening in the annular passage based on operating conditions. This allows the axial force to be actively adjusted during load changes, preventing thrust reversal and vibrations while maintaining a relatively simple structural configuration.
4Force
If pressure balance pistons are used for thrust balance, then axial thrust is reduced, but installation space and axial length are increased
Solution Approach 1:
The invention merges the thrust balancing function with the existing annular passage structure. Instead of adding separate balance pistons and chambers that extend the axial length, the balancing mechanism is integrated into the cooling air passage, eliminating the need for additional axial space.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the maximum thrust on thrust bearings, prevents thrust reversal, and allows for controlled axial force management across the entire load range without additional structural components or compressed air consumption, enhancing efficiency and stability.
Implementation Method 1
applying a positive additional thrust in a controlled manner... utilizing existing structural components... The axial force of the piston during normal operation is reduced by a second chamber which is exposed to pressure application
Implementation Method 2
The axial thrust of a gas turbine is the resulting force from aerodynamic forces and pressure forces which exert an axial force upon the rotor in the compressor and turbine
Implementation Method 3
cooling air inside the annular passage on the rotor side being deflected through a swirl cascade and being accelerated to the highest possible tangential velocity
Data Source
AI summary
A method for axial thrust control of a gas turbine, and a gas turbine with a device for controlling axial thrust are provided. A gas turbine, with regard to aerodynamic forces and pressure forces, which exert an axial force upon the rotor, is configured such that at no-load and low partial load it has a negative thrust, and at high load it has a positive thrust. In order to ensure a resulting positive thrust upon the thrust bearing within the entire load range of the gas turbine, an additional thrust is applied in a controlled manner. The additional thrust for example can be controlled in dependence upon the gas turbine load. The resulting thrust force at full load is consequently less than in the case of a conventionally designed gas turbine without thrust balance.