Open Rotor Blade Cooling Using Ambient Air Intakes
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Solution Overview
Problem
Current cooling systems for open rotor gas turbine engines, which rely on compressor-bled air, suffer from reduced compressor performance, added weight due to feed pipes and valves, and the need for air to cross a rotating boundary, while also requiring significant cooling air to manage hot exhaust gases impinging on propeller blades.
Innovation Solution
A cooling system that uses ambient air, directed radially outwardly of the exhaust gas impingement point on the blades, eliminating the need for compressor-bled air and reducing weight and drag, with intakes located optimally to minimize performance loss and using a central plenum to combine and distribute cooling air, and outlets positioned to create a pressure difference for airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air is bled from the compressor to cool the propeller blades, then the blades are cooled effectively, but compressor performance deteriorates
Solution Approach 1:
The invention extracts the cooling air source from the compressor system and relocates it to ambient air intake positioned radially outward of the exhaust gas impingement point. This separation eliminates the trade-off between blade cooling and compressor performance by obtaining cooling air from an external source rather than extracting it from the compressor flow path.
2Temperature
If a network of feed pipes and valves is used to supply cooling air from the compressor, then cooling is achieved, but engine weight increases
Solution Approach 1:
The invention removes the complex feed pipe and valve network from the cooling system by directly introducing ambient air into the blade cooling channels through radially outward intakes. This eliminates the weight penalty associated with extensive piping and valving while maintaining effective cooling functionality.
3Temperature
If cooling air is supplied from the compressor, then cooling is provided, but the air must cross a rotating boundary which complicates the system
Solution Approach 1:
The invention eliminates the rotating boundary crossing requirement by sourcing cooling air from ambient environment through stationary intakes positioned radially outward of the exhaust path. This removes the complexity of rotary joints or seals needed to transfer air across the rotating blade boundary.
4Quantity of substance
If the intake is located radially outward of the exhaust gas impingement point, then ambient air is used for cooling reducing the quantity required, but the intake position must be optimized to minimize drag
Solution Approach 1:
The invention applies local quality optimization by positioning the intake at a specific radial location outward of the exhaust impingement point where ambient air flow is favorable. The intake location is carefully selected to capture cool ambient air while minimizing disruption to the propeller blade aerodynamic performance, balancing cooling effectiveness with drag reduction.
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 the quantity of cooling air required, minimizes compressor performance impact, eliminates the need for rotating boundary crossings, and reduces weight and noise, while providing effective cooling and anti-ice functionality with a more efficient and robust cooling system.
Implementation Method 1
ambient air, rather than compressor air, can be used to cool the blade. As ambient air is substantially cooler than compressor air, a smaller quantity of cooling air is required to obtain a similar cooling effect.
Implementation Method 2
each blade has an internal cooling network through which cooling air flows to cool the blade in respect of the hot exhaust gases
Data Source
AI summary
A cooling system for an open rotor gas turbine engine is provided. The system comprises an engine exhaust, and a row of open rotor propeller blades located rearwardly of the exhaust such that hot exhaust gases impinge on the propeller blades. Each blade has an internal cooling network through which cooling air flows to cool the blade in respect of the hot exhaust gases. Each blade also has one or more intakes which provide cooling air to the cooling network. The or each intake is located radially outwardly of the position of impingement of the hot exhaust gas on the blade.