Turbomachine Compressor Air Injection System
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Solution Overview
Problem
High pressure compressor turbomachines face performance and operability issues due to clearance between rotor blades and the casing, leading to friction losses and air-flow separation, which limit the operating range and efficiency.
Innovation Solution
An air injection system with an outlet segment that opens inclined upstream from the rotor blades into a set-back zone of the casing, minimizing disturbance to the air stream and reducing clearance-related performance losses by injecting a small flow rate of air upstream, preferably into the first rotor wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air recirculation is established by bleeding air and reinjecting it upstream from rotor blade tips, then the clearance effect is reduced and compressor operability is improved, but significant disturbance is caused to the air stream at the injection location
Solution Approach 1:
A dedicated air injection passage is introduced as an intermediary structure to deliver recirculated air to a specific location (set-back zone) upstream from the rotor blades. This passage serves as a controlled mediator that manages the injection process, directing air through a defined path with an outlet segment oriented at a specific angle to minimize disruption to the main air stream while maintaining the beneficial clearance effect reduction.
2Loss of energy
If the outlet segment of the air injection passage opens inclined upstream towards rotor blades, then air stream disturbance is minimized and performance losses are reduced, but the device complexity increases
Solution Approach 1:
The air injection passage is designed with differentiated local characteristics: the outlet segment is specifically oriented at an inclined angle upstream towards the rotor blades, while other portions of the passage may have different geometries. This localized optimization of the outlet orientation minimizes air stream disturbance and performance losses at the critical injection point without requiring complex modifications throughout the entire passage structure.
3Productivity
If air injection is performed into the set-back zone upstream from rotor blades, then clearance-related performance losses are reduced, but the manufacturing complexity increases
Solution Approach 1:
The air injection passage is designed as a segmented structure with distinct functional zones: an upstream segment, a middle segment, and an outlet segment with specific orientation. This segmentation allows each portion to be optimized independently for its specific function while simplifying the overall manufacturing process, as each segment can be machined or formed separately and then assembled into the casing.
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
Significantly improves the operating range and reduces performance losses associated with clearance, while being lightweight and easily integratable into existing engine technology without increasing casing weight.
Implementation Method 1
the outlet segment opens out in inclined manner upstream from and directed towards a row of rotor blades into a set-back zone ('trench') of the inside face of the casing... makes it possible to inject air upstream from said row of rotor blades without significantly disturbing the air stream... enables the stability range of the compressor to be extended
Data Source
AI summary
A turbomachine or high pressure compressor including a stator casing housing a plurality of compression stages that are spaced apart in an axial direction along the central axis of the turbomachine, each compression stage including a row of rotor blades followed by a row of stator vanes. The compressor further includes an air injection system including at least one air injection passage through the casing and including an outlet segment that opens out in an inclined manner upstream from and directed towards a row of rotor blades into a set-back zone of the inside face of the casing.