Gas Turbine Rotor Overspeed Control via Stator Temperature Detection
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Solution Overview
Problem
In multi-spool turbojets, shaft breakage leads to rapid rotor overspeed due to unbalanced mechanical load, causing potential catastrophic failure, and existing solutions like axial displacement mechanisms and fuel supply interruption are costly and inefficient.
Innovation Solution
Measuring temperature on the stator surface downstream of the rotor and using thermocouple sensors to control fuel supply shutdown when a threshold is reached, preventing rotor overspeed by eliminating energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If axial displacement mechanisms with fins are used to brake the rotor, then rotor speed is reduced, but significant damage occurs to the blades and repair costs increase
Solution Approach 1:
The patent replaces the mechanical braking system (fins and blades) with a thermal detection system (thermocouples) coupled with fuel supply control. Instead of mechanically dissipating kinetic energy through friction, the system detects shaft failure thermally and eliminates energy input by cutting fuel supply, thereby avoiding mechanical damage to blades.
Solution Approach 2:
The patent extracts the braking function from the mechanical rotor-stator interaction and relocates it to the fuel supply control system. The thermocouples detect the failure condition, and the control system responds by removing the energy source (fuel), separating the detection and braking functions from the mechanical components that would otherwise be damaged.
2Speed
If redundant speed measurement means are used to detect overspeed, then rotor speed control is achieved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical speed measurement systems (tachometers, encoders at bearing locations) with a thermal detection system. Thermocouples mounted on the stator detect shaft failure through temperature changes caused by altered heat transfer patterns, converting a mechanical measurement problem into a thermal detection problem that is simpler and more reliable.
Solution Approach 2:
The patent introduces temperature as an intermediary parameter to detect shaft failure and control rotor speed. Instead of directly measuring speed or position, the system uses temperature changes on the stator surface as an indirect indicator of shaft integrity, which then triggers fuel supply control to achieve speed regulation.
3Measurement precision
If temperature measurement is used to detect shaft failure, then detection speed and accuracy improve, but response time must be sufficient to prevent overspeed
Solution Approach 1:
The patent positions thermocouples on the stator surface in advance, ready to detect temperature changes immediately upon shaft failure. The system is pre-configured with temperature thresholds that, when exceeded, automatically trigger fuel supply cutoff, eliminating detection and response delays.
Solution Approach 2:
The patent monitors temperature as a dynamic parameter that changes rapidly upon shaft failure. By setting a predetermined temperature threshold that corresponds to shaft failure conditions, the system achieves rapid and accurate detection without complex measurement systems, as temperature rises quickly and distinctly when the shaft fails.
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 method effectively limits rotor speed and prevents catastrophic failure by quickly interrupting fuel supply, reducing damage and enhancing safety, mass efficiency, and part resistance.
Implementation Method 1
measuring the temperature on a surface of the stator located downstream of the rotor... An advantageous means is to measure the temperature with a thermocouple sensor
Implementation Method 2
All it takes is an axial movement over a short distance for the rotor to come into contact with the stator and very quickly induce significant heating by friction
Data Source
Figure 1~3
AI summary
The method involves measuring temperature in a point on a surface (10a) of a stator situated downstream of a rotor (6) using a thermocouple sensor. A measurement signal is transmitted to a braking control unit of a rotor, where the control unit controls the braking of the rotor when the temperature attains a threshold and controls fuel in a combustion chamber of the engine. The threshold is greater than a maximum temperature to be attained during the engine operation. An independent claim is also included for a device for reducing rotational speed of a turbine in a gas turbine engine.