Bleed Duct Airfoils for Gas Turbine Flow Alignment
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Solution Overview
Problem
Obstructions and disruptive airflows in gas turbine engines can disturb bypass airflow, affecting propulsive efficiencies and overall engine performance, particularly in the intermixing of bleed air with bypass airflow.
Innovation Solution
The use of airfoils disposed at a chord angle of between 40° and 55°, oriented transverse to the engine axis, to direct bleed airflow into the bypass passage, minimizing disruptions and optimizing the alignment of bleed air with the bypass flow, thereby reducing flow disturbances and pressure losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If bleed air is directed into the bypass passage to improve efficiency, then thermal efficiency is improved, but flow disturbances and pressure losses increase
Solution Approach 1:
The bleed duct is divided into multiple segments with individual airfoils arranged in a array. Each airfoil segment directs bleed air at specific angles, allowing the flow to be progressively aligned with the bypass airflow direction, reducing overall flow disturbance and pressure losses while maintaining thermal efficiency benefits
Solution Approach 2:
Different sections of the bleed duct have airfoils with different chord angles optimized for their specific location. The airfoils are arranged to create localized flow control, with each section addressing specific flow disturbance patterns to minimize pressure losses while directing bleed air into the bypass passage
2Productivity
If bleed air is directed into the bypass passage, then engine performance is improved, but flow disturbances increase
Solution Approach 1:
The airfoils are oriented transverse to the engine axis rather than parallel, creating a three-dimensional flow distribution pattern. This dimensional change allows bleed air to be injected perpendicular to the main airflow direction and then gradually aligned, reducing flow disturbances while maintaining engine performance benefits
Solution Approach 2:
The chord angle of the airfoils is optimized at between 40° and 55° to change the flow direction parameters. This parameter optimization ensures that bleed air is directed at angles that promote smooth mixing with bypass airflow, reducing flow disturbances while maintaining improved engine performance
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 configuration enhances propulsive efficiency by minimizing disruptions and acoustic impacts, improving the alignment of bleed air with bypass airflow, leading to increased engine performance and efficiency.
Implementation Method 1
A plurality of airfoils are provided in the duct. The airfoils define passages for directing bleed airflow into the bypass passage
Data Source
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AI summary
A disclosed gas turbine engine includes a fan including a plurality of fan blades rotatable about an engine axis and core engine disposed within a core nacelle for driving the fan. A bypass passage is defined between the core nacelle and an outer or fan nacelle. A duct mounted within the core nacelle defines a bleed air flow path for directing bleed air from the core engine into the bypass passage. The bleed air duct includes a plurality of airfoils disposed at a defined chord angle for directing bleed airflow into the bypass passage to minimize disruption to bypass airflow.