Turbine Cooling-Air Casing with Undulating Channels for Lower Leakage
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Solution Overview
Problem
Existing air injection systems for turbomachine turbines face challenges in maximizing airflow at injector necks without pressure drop, controlling air flow and distribution, and reducing seal leakage and mass, while maintaining robustness across varying operating conditions.
Innovation Solution
A cooling air injection casing with channels featuring a primary section extending axially, a secondary section with tangential orientation, undulations, and a reduced section, along with outlet mouths closer to the longitudinal axis, enhances airflow efficiency and reduces leakage through sealing devices, manufactured via additive manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional axial injectors with fixed-angle holes or static blades are used, then the structure is simple and easy to manufacture, but the mass of the assembly is significant and airflow control is insufficient
Solution Approach 1:
The patent changes the geometric parameters of the injection channels by introducing undulations and varying cross-sections along the channel length. This transforms the conventional straight, constant-section channels into complex three-dimensional channels with optimized flow characteristics, achieving better airflow control and reduced mass without compromising manufacturability through additive manufacturing
Solution Approach 2:
The patent transitions from two-dimensional cross-sectional views of injection channels to three-dimensional undulating channels with varying orientation angles. The channels now have spatial complexity with undulations in multiple dimensions, allowing optimized airflow paths that reduce mass while maintaining ease of manufacture through modern manufacturing processes
2Reliability
If conventional injectors are used, then the structure is robust, but airflow separation risk increases and pressure drop occurs at injector necks
Solution Approach 1:
The patent introduces dynamic characteristics to the injection channels through undulations and varying cross-sections. The channels are no longer static, straight passages but have complex three-dimensional geometries that adapt the flow dynamically, reducing pressure drop and preventing airflow separation while maintaining system robustness
Solution Approach 2:
The patent applies curvature to the injection channels through undulations instead of using straight, angular channels. The curved, undulating paths of the channels reduce flow separation and pressure drop by creating smoother flow transitions, while the robustness is maintained through the overall structural integrity of the casing
3Device complexity
If outlet mouths are positioned at larger radius, then the injector structure is simpler, but leakage rates through sealing devices increase
Solution Approach 1:
The patent inverts the conventional approach by positioning outlet mouths closer to the rotational axis rather than at larger radii. This counterintuitive positioning, combined with the undulating channel geometry, actually simplifies the overall injector structure while reducing leakage rates through sealing devices located near the injectors
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
The solution achieves higher tangential velocity, improved cooling efficiency, reduced leakage, and a 50% decrease in mass compared to conventional systems, ensuring robust operation and enhanced cooling of turbomachine rotor discs.
Implementation Method 1
the channel has a reduction in section between the inlet section of the inlet mouth and the section of a neck
Implementation Method 2
the channel has at least one undulation in its primary section, so that the outlet mouth is located closer to the longitudinal axis than the inlet mouth
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The present invention relates to a cooling-air injection casing (2) for cooling a bladed rotor disc of a turbine, in particular a high-pressure turbine, of a turbomachine, this casing extending around a longitudinal axis (X-X') and being traversed by at least one channel (20) forming an air injector, the channel (20) comprising an inlet mouth (201) and an outlet mouth (202). This casing is noteworthy in that the channel (20) comprises a primary section (203) which extends in an axial plane (P) from the inlet mouth (201) to an elbow (206), and a secondary section (207) which extends from this elbow (206) to the outlet mouth (202), the secondary section (207) having a progressive variation of its orientation with a tangential component between the elbow (206) and the outlet mouth (202), in that the channel (20) has a reduction in cross section between the inlet mouth (201) and a neck (204), and in that the channel (20) has at least one corrugation (205) in its primary section (203), such that the outlet mouth (202) is situated closer to the longitudinal axis (X-X') than the inlet mouth (201).