Stator Wall Depressions for Compressor Corner Loss Reduction
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Solution Overview
Problem
Aircraft engine compressors experience performance impairments due to corner losses and secondary flows, particularly when the stator is highly loaded, leading to boundary layer buildup, flow deviation, and corner separation.
Innovation Solution
The introduction of depressions in the stator walls, located between the pressure and suction sides, which axially overlap the airfoils and are closer to the suction side, reducing boundary layer buildup and flow deviation by lowering the local Mach number and inducing gentler diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the stator is highly loaded to increase compressor performance, then power and efficiency are improved, but corner losses and secondary flows increase causing boundary layer buildup and flow deviation
Solution Approach 1:
The patent applies local quality by introducing depressions at specific locations in the stator wall gaspath surface, particularly near corner regions where secondary flows and boundary layer buildup occur. These localized geometric modifications create region-specific flow control effects without altering the overall stator loading, thereby reducing corner losses while maintaining compressor power output.
Solution Approach 2:
The patent changes the geometric parameters of the stator wall by introducing depressions with specific dimensions, depths, and positions. These parameter modifications alter the local flow field characteristics, reducing secondary flows and boundary layer accumulation in high-loss regions while preserving the overall compression performance.
2Power
If the stator is highly loaded to increase compressor performance, then power is improved, but flow deviation and corner separation occur
Solution Approach 1:
The depressions are strategically positioned in corner regions and near leading edges where flow separation and deviation are most problematic. This localized intervention stabilizes the boundary layer in critical areas without disrupting the overall flow pattern required for high compressor performance, thereby improving flow stability while maintaining power output.
Solution Approach 2:
The depressions create preliminary flow control effects that counteract the development of adverse pressure gradients and secondary flows before they can cause corner separation. By introducing these geometric features upstream in the flow path, the patent prevents flow instability from developing, ensuring reliable operation at high loading conditions.
3Loss of energy
If depressions are added to reduce boundary layer buildup, then corner losses are reduced, but device complexity increases
Solution Approach 1:
The depressions create a controlled porosity or surface irregularity in the stator wall gaspath surface, which facilitates boundary layer control and reduces corner losses. This approach uses simple geometric modifications rather than complex active control systems, maintaining manufacturing feasibility while achieving the desired flow control effects.
Solution Approach 2:
The patent introduces a new dimensional feature (depth) to the stator wall surface by creating depressions, transforming a two-dimensional surface into a three-dimensional structure. This dimensional change enables flow control functionality without adding separate components, thereby reducing overall device complexity while effectively reducing corner losses.
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 depressions reduce corner losses, improve flow conditions, and enhance the overall performance of the compressor and downstream components by minimizing boundary layer buildup and wake shedding.
Implementation Method 1
reducing boundary layer buildup and flow deviation by lowering the local Mach number and inducing gentler diffusion
Implementation Method 2
inducing gentler diffusion
Implementation Method 3
reducing boundary layer buildup
Implementation Method 4
minimizing boundary layer buildup and wake shedding
Data Source
AI summary
A fluid machine for an aircraft engine has: first and second walls; a gaspath defined between the first wall and the second wall; a rotor having blades rotatable about the central axis; and a stator having: a row of vanes having airfoils including leading edges, trailing edges, pressure sides and suction sides opposed the pressure sides, and depressions defined in the first wall, the depressions extending from a baseline surface of the first wall away from the second wall, a depression of the depressions located circumferentially between a pressure side of the pressure sides and a suction side of the suction sides, the depression axially overlapping the airfoils and located closer to the suction side than to the pressure side, an upstream end of the depression located closer to a leading edge of the leading edges than to a trailing edge of the trailing edges.