Axial Compressor Bleed Cavity Airflow Deflector
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Solution Overview
Problem
The rapid extraction of compressed air from annular bleed cavities in gas turbine engines during transient maneuvers leads to significant temperature differences, causing thermal deformation of the vane carrier section, which can result in compressor blade rubbing and reduced performance due to increased clearances between stator and rotor assemblies.
Innovation Solution
The implementation of air deflector members within the bleed cavities, which are designed to divert and guide the airflow, reducing turbulence and vortices, thereby minimizing the heat transfer coefficient and thermal expansion, and are preferably annular in shape with a circumferentially arranged flap portion to smoothly direct airflow towards the air outlets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compressed air is rapidly extracted from annular bleed cavities during transient maneuvers, then air blow off is achieved for stable operation, but thermal deformation of the vane carrier section occurs due to high temperature difference
Solution Approach 1:
A thermal barrier is introduced as an intermediary element between the cold compressed air in the bleed cavity and the hot vane carrier section. This barrier reduces heat transfer during rapid air extraction, preventing thermal deformation of the vane carrier while allowing stable operation during transient maneuvers.
Solution Approach 2:
A thin thermal barrier layer or coating is applied to the vane carrier section adjacent to the bleed cavity. This thin film acts as a thermal shield that prevents direct thermal contact between the cold air and the hot vane carrier, eliminating thermal deformation during air blow off operations.
2Reliability
If clearances between stator and rotor assemblies are increased to avoid rubbing, then compressor blade rubbing is prevented, but performance and stability are reduced
Solution Approach 1:
The thermal barrier is applied beforehand to the vane carrier section to prevent thermal deformation that would cause rubbing. By preventing the thermal shock-induced shrinkage before it can cause blade rubbing, the original clearances are maintained, preserving compressor performance and stability.
3Stability of the object's composition
If air deflector members are added to divert airflow, then thermal expansion is reduced, but device complexity increases
Solution Approach 1:
Instead of adding complex three-dimensional air deflector members, a simple thermal barrier layer or coating is applied to the vane carrier section. This thin film approach reduces thermal expansion effectively while adding minimal complexity to the device structure.
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 solution reduces thermal expansion and pressure losses, allowing for smaller clearances between stator and rotor assemblies, enhancing compressor performance and stability without reducing the inner volume of the bleed cavities.
Implementation Method 1
reducing turbulence and vortices
Implementation Method 2
minimizing the heat transfer coefficient and thermal expansion
Data Source
Figure 1~8
Figure 2
Figure 3~5
AI summary
Axial compressor (1) comprising: a tubular casing (2); a drive shaft (3) extending in axially rotatable manner inside the central cavity (2a) of said casing (2) coaxial to the latter; a number of annular blade rows (4) spaced along and stably fixed to the drive shaft (3); a number of annular vane rows (6) stably fixed to the peripheral wall (8) of said casing (2) intercalated to the annular blade rows (4); at least one bleed cavity (9) formed within the peripheral wall (8) of said casing (2); at least one bleeding slot (11) which is formed in the peripheral wall (8) to put said bleed cavity (9) into direct communication with the central cavity (2a) of said casing (2); and at least one air deflector member (15) which is located inside the bleed cavity (9), and is adapted to divert/guide the airflow (f) of compressed air entering and/or circulating inside the bleed cavity (9) for reducing the air turbulence area inside the bleed cavity (9) .