Angled On-Board Injector for Compact Turbine Cooling
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Solution Overview
Problem
Conventional gas turbine engine cooling structures, such as Tangential On-Board Injectors (TOBI), face challenges in compact packaging and efficiency for small engines, requiring significant radial height and leading to overheating of turbine blades due to inadequate cooling air distribution.
Innovation Solution
The Angled On-Board Injector (AOBI) locates a metering throat at an inward angle relative to the engine centerline, featuring an annular upstream and downstream wall with an interconnecting body, allowing for minimized axial and radial packaging, and directing cooling air radially inward to conserve radial height and reduce losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional Tangential On-Board Injector (TOBI) is used, then cooling air can be effectively distributed to turbine blades, but the radial height requirement increases and packaging becomes complicated
Solution Approach 1:
The patent transitions from a conventional radial/tangential injection geometry to an angled injection geometry that utilizes both radial and axial dimensions. The injector is positioned at an angle between 0-90 degrees relative to the radial direction, allowing the cooling air to be delivered along an angled path that reduces the required radial height while maintaining effective cooling air distribution to the turbine blades.
Solution Approach 2:
The patent changes the geometric parameters of the injector system by introducing an angled configuration instead of a purely radial or tangential one. By adjusting the injection angle and the positioning of the injector relative to the turbine rotor assembly, the system achieves compact packaging with reduced radial height while preserving cooling effectiveness through optimized flow direction and distribution patterns.
2Reliability
If cooling air flow volume is increased to prevent turbine blade overheating, then blade cooling effectiveness improves, but combustion efficiency is penalized
Solution Approach 1:
The angled injector design enables more precise local delivery of cooling air directly to the turbine blade leading edges and suction surfaces where cooling is most critical. By angling the injection, the cooling air is delivered more efficiently to specific high-heat zones on the blade, improving local cooling effectiveness and allowing for reduced overall cooling air flow, thereby minimizing the penalty on combustion efficiency.
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 AOBI provides a compact cooling structure that effectively transfers cooling air to turbine blades with reduced radial height and axial spacing, minimizing losses and optimizing engine performance by allowing flexible design and lower cavity pressure requirements.
Implementation Method 1
The AOBI includes a generally annular upstream wall, an annular downstream wall and an annular body which interconnects the upstream and downstream walls. The upstream wall and the downstream wall interface with an annular inner flow path wall such that cooling air from a turbine vane is directed into the AOBI and toward an angled annular section of a turbine rotor coverplate.
Implementation Method 2
The angled annular section is located at a corresponding angle relative the engine centerline such that the angled annular section is generally transverse to the AOBI nozzle. The AOBI allows for a flexible design which can be optimized such that the axial and radial packaging is minimized.
Data Source
Figure 1~2
Figure 3A~3C
AI summary
A secondary flow system provides a compact injector cooling structure for turbine blades (20) which includes an Angled On-board Injector (AOBI) (40) that locates a metering throat (41) at an inward angle relative to an engine centerline (W). The AOBI (40) positions the metering throat (41) at the inward angle relative to an engine centerline (W) to communicate cooling airflow to an angled annular section (38) of a turbine rotor disk coverplate (30).