Active Radial Clearance Control in Turbomachine Casing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing turbomachine systems face challenges in precisely controlling radial clearance between rotor blades and the outer casing due to centrifugal forces, leading to imprecise geometry variations and uncontrolled movement of stator vanes, which affects compressor outlet pressure and efficiency.
Innovation Solution
An active radial clearance control system using an oil circuit with an expansion module inside the casing to deform the outer casing, utilizing heat from the oil to adapt radial play, comprising an annular partition with an expansion ring and ducts made of metallic or composite materials, with a higher expansion coefficient than the casing, to control radial clearance between rotor blades and the outer casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the outer casing is deliberately expanded to control radial clearance, then the radial clearance can be adapted, but the geometry variation remains imprecise causing uncontrolled stator vane movement
Solution Approach 1:
The patent applies thermal expansion by circulating hot oil through the outer casing to deliberately expand it and adapt the radial clearance. The oil circuit recovers calories from turbomachine equipment and uses this thermal energy to expand the casing, precisely controlling the radial play between rotor blades and casing while maintaining stator vane stability.
Solution Approach 2:
The patent changes the temperature parameter of the outer casing by introducing hot oil circulation. By controlling the oil temperature and flow, the system dynamically adjusts the casing dimensions to compensate for centrifugal force effects, achieving precise radial clearance control and stable stator vane positioning throughout the operating range.
2Manufacturing precision
If oil is used to drive expansion of the housing, then radial clearance can be adapted, but the system complexity increases
Solution Approach 1:
The patent applies multi-functionality by using the oil circuit for multiple purposes: lubricating bearings, recovering thermal energy from turbomachine equipment, and driving the thermal expansion of the outer casing for radial clearance control. This integrates several functions into a single system, reducing overall complexity despite the added thermal control capability.
Solution Approach 2:
The system applies self-service by recovering calories from the turbomachine's own operation and using this internally generated thermal energy to drive the casing expansion. The oil circuit lubricates bearings and simultaneously provides thermal energy for clearance control, making the system self-sufficient and reducing external complexity.
3Manufacturing precision
If the outer casing is expanded to compensate for centrifugal force, then radial clearance is controlled, but the system requires more oil flow
Solution Approach 1:
The patent applies discarding and recovering by capturing the thermal energy that would otherwise be wasted in the lubricating oil and bearings. The oil circuit recovers calories from the turbomachine equipment and redirects this thermal energy to drive the casing expansion, eliminating the need for additional oil flow while maintaining precise radial clearance control.
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 system effectively controls radial clearance, reducing leaks and optimizing efficiency across different operating modes, enhancing the durability and precision of the turbomachine by fine-tuning the vane-casing clearance, thereby improving the overall performance of the turbojet engine.
Implementation Method 1
an expansion module configured to deform the outer casing using the calories recovered by the oil
Implementation Method 2
the module comprises at least one duct arranged in its radial thickness... configured to deform the outer casing using the calories recovered
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to an active radial clearance control system (40) around an annular row of rotor blades (34) of a turbomachine, particularly rotor blades (34) of a low-pressure compressor for an aircraft turbojet engine. The system (40) comprises an annular row of rotor blades (34); an external housing (26) around the row of rotor blades (34); radial clearance (44) between the rotor blades (34) and the external housing (26); and an oil circuit (24) adapted to recover heat from a reduction gear such as an epicyclic gear train driving the fan. The oil circuit (24) includes an expansion module (46) configured to expand due to the heat recovered by the oil. This expansion module (46) is placed inside the housing (26) so as to modulate its diameter around the rotor blades (34). The invention also proposes a turbomachine such as a turbojet engine.