Interdigitated Counter-Rotating Turbine for Gas Engine Efficiency
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Solution Overview
Problem
Conventional gas turbine engines face inefficiencies due to the need for significant cooling air to mitigate damage from hot combustion gases, which reduces overall engine efficiency, performance, and operability, and are limited by the design of nozzle guide vanes that require substantial cooling, increasing maintenance and repair needs.
Innovation Solution
The implementation of an interdigitated turbine section with a low speed turbine rotor, a high speed turbine rotor, and an intermediate speed turbine rotor, where the low speed turbine rotor is coupled to the fan rotor via a low pressure shaft, and the high speed turbine rotor is coupled to the high pressure compressor, allowing for counter-rotation and reduced cooling air consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional nozzle guide vanes are used to accelerate combustion gases to match turbine rotor speed, then engine operability and performance are improved, but significant quantities of cooling air are required which adversely affects overall engine efficiency and fuel consumption
Solution Approach 1:
The patent inverts the conventional approach by using a counter-rotating turbine rotor instead of a stationary nozzle guide vane to accelerate combustion gases. The counter-rotating rotor moves opposite to the gas flow direction, creating a velocity addition effect that accelerates gases without requiring cooling air, thus resolving the contradiction between operability improvement and energy loss.
Solution Approach 2:
The patent extracts and eliminates the stationary nozzle guide vane component from the turbine section, replacing it with a counter-rotating turbine rotor. This removal of the problematic component (nozzle guide vane requiring cooling air) while retaining its function (gas acceleration) directly addresses the contradiction by eliminating the source of energy loss.
2Strength
If nozzle guide vanes are designed to withstand maximum combustion gas temperature along the annulus, then structural integrity is maintained, but significant quantities of cooling air are consumed increasing maintenance and repair needs
Solution Approach 1:
The patent removes the stationary nozzle guide vane component that requires cooling air and is subject to thermal damage. By replacing it with a counter-rotating turbine rotor operating in the same gas flow, the component requiring protection from hot spots is eliminated, thereby reducing maintenance needs while maintaining structural integrity through the rotor design.
Solution Approach 2:
The counter-rotating turbine rotor serves itself by operating directly in the combustion gas flow without requiring separate cooling air supplies. The rotor is designed to withstand the thermal environment through its rotating operation and material selection, eliminating the need for external cooling systems and reducing maintenance requirements.
3Loss of energy
If interdigitated turbine rotors are configured to reduce cooling air consumption, then engine efficiency is improved, but the number of rotating components and packaging complexity increases
Solution Approach 1:
The patent merges the functions of the nozzle guide vane and the first turbine stage into a single counter-rotating turbine rotor. This consolidation eliminates the need for separate stationary and rotating components, reducing packaging complexity while maintaining the efficiency benefits of counter-rotation and eliminating the need for cooling air.
Solution Approach 2:
The counter-rotating turbine rotor performs multiple functions: it acts as both the gas acceleration device (replacing the nozzle guide vane) and the first turbine stage for power extraction. This multi-functionality reduces the total number of components and simplifies packaging while achieving the desired efficiency improvement.
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 configuration enhances engine efficiency, performance, and operability by reducing cooling air usage, minimizing the need for cooling, and allowing for additional stages of interdigitation, thereby decreasing part quantities, weight, and packaging dimensions while maintaining or improving power output.
Implementation Method 1
rotating the low speed turbine rotor in a first direction along the circumferential direction; rotating the high speed turbine rotor in a second direction opposite of the first direction along the circumferential direction
Implementation Method 2
a turbine section downstream of a combustion section that is rotatable with a compressor section to rotate and operate the gas turbine engine to generate power
Data Source
AI summary
The present disclosure is directed to a method of operating a gas turbine engine with an interdigitated turbine section. The engine includes a fan rotor, an intermediate pressure compressor, a high pressure compressor, a combustion section, and a turbine section in serial flow arrangement. The turbine section includes, in serial flow arrangement, a first stage of a low speed turbine rotor, a high speed turbine rotor, a second stage of the low speed turbine rotor, an intermediate speed turbine rotor, and one or more additional stages of the low speed turbine rotor. The low speed turbine rotor is coupled to the fan rotor via a low pressure shaft. The intermediate speed turbine rotor is coupled to the intermediate pressure compressor via an intermediate pressure shaft. The high speed turbine rotor is coupled to the high pressure compressor via a high pressure shaft. The method includes rotating the low speed turbine rotor in a first direction along the circumferential direction; rotating the high speed turbine rotor in a second direction opposite of the first direction along the circumferential direction; and rotating the intermediate speed turbine rotor in the second direction.