Reverse Thrust Engine Core Casing Flow Passage Design
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Solution Overview
Problem
Existing gas turbine engines experience significant flow distortion and performance degradation during reverse thrust operations due to the introduction of aft-to-forward airflow, which is not streamlined for normal forward-to-aft airflow directions, leading to inefficient compressor performance.
Innovation Solution
A gas turbine engine design featuring a core casing with a reverse flow passage that allows direct airflow into the core engine during reverse thrust, minimizing swirl and optimizing airflow through the use of variable pitch fan blades and strategically positioned stator vanes and struts to reduce distortion, along with active control mechanisms for managing airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If air is forced around the engine during reverse thrust before entering the compressor inlet, then reverse thrust is generated, but significant swirl or flow distortion is introduced into the airflow
Solution Approach 1:
The engine is divided into separate flow paths: a normal forward flow path for forward thrust operations and a dedicated reverse flow path with its own inlet and passage for reverse thrust operations. This segmentation allows each path to be optimized for its specific flow direction, preventing flow distortion in the compressor inlet during reverse thrust.
Solution Approach 2:
A reverse flow inlet and dedicated reverse flow passage act as intermediaries between the rearward air source and the compressor inlet during reverse thrust operations. These intermediary structures provide a controlled pathway that eliminates the need for air to force around the engine, thereby reducing swirl and flow distortion.
2Force
If the propeller pitch is rotated to generate reverse thrust, then air is drawn from rearward portion of the engine, but the engine performance deteriorates due to unstreamlined airflow
Solution Approach 1:
The engine incorporates separate reverse flow inlets and passages that are specifically designed and streamlined for rearward-to-forward airflow. This segmentation allows the engine to maintain optimized airflow patterns for both forward and reverse thrust operations, preserving engine performance while enabling reverse thrust capability.
Solution Approach 2:
The reverse flow passage and inlet are designed with specific local geometric characteristics optimized for reverse airflow patterns. The passage includes carefully shaped turns and transitions that minimize turbulence and swirl, creating locally optimized flow conditions that maintain overall engine performance during reverse thrust operations.
3Productivity
If existing engines are designed for normal forward airflow, then forward thrust performance is optimized, but reverse thrust operations cause swirl and flow distortion
Solution Approach 1:
The engine is segmented into distinct flow paths: a normal forward flow path that maintains optimized streamlined geometry for forward thrust performance, and a separate reverse flow path with dedicated inlet and passage designed specifically for reverse thrust operations. This segmentation allows each path to be independently optimized for its flow direction.
Solution Approach 2:
The reverse flow inlet and passage serve as intermediary structures that intercept rearward airflow and guide it through a controlled pathway to the compressor inlet. These intermediaries prevent the unstreamlined airflow that would otherwise cause swirl and flow distortion, while allowing the main forward flow path to remain optimized for normal operations.
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 design significantly reduces flow distortion and enhances engine performance during reverse thrust operations by stabilizing airflow and maintaining efficient compressor performance, even when reversing thrust direction.
Implementation Method 1
a plurality of variable pitch fan blades for generating a forward thrust and a reverse thrust
Implementation Method 2
a reverse flow passage extending from an outer surface entrance to an inner surface exit
Implementation Method 3
strategically positioned stator vanes and struts to reduce distortion
Data Source
AI summary
A propulsion device that defines a central axis and a circumferential direction is provided. The propulsion device may include a core engine and a core casing. The core engine may include an engine shaft extending along the central axis. The core casing may have an inner surface and an outer surface. The core casing may extend along the circumferential direction about the propulsion device, as well as along the central axis from a forward end to an aft end. The core casing may define a primary air flowpath having an annular inlet at the forward end and an exhaust at the aft end. The core casing may further define a reverse flow passage extending from an outer surface entrance to an inner surface exit.