Unducted Propulsion Housing Flowpath Curve Design
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Solution Overview
Problem
Existing unducted propulsion systems face inefficiencies in thrust production due to energy losses, swirl, frictional drag, and shockwave-related drag forces, limiting aircraft cruise speeds to below Mach 0.72.
Innovation Solution
The unducted propulsion system incorporates a unique shape for the external surface of housings, featuring a flowpath curve with specific ratios and geometrical parameters, such as bulge and local minimum radii, to minimize drag and maximize thrust efficiency at high subsonic cruise speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional housing shapes are used in unducted propulsion systems, then the system structure is simple, but wave drag and frictional drag increase, limiting cruise speed to below Mach 0.72
Solution Approach 1:
The patent applies curved flowpath surfaces with specific radii of curvature to the housing design. The flowpath curve includes a bulge region with a first radius of curvature and a trough region with a second radius of curvature, where the ratio of these radii is optimized to reduce adverse pressure gradients and minimize wave drag and frictional drag at high subsonic speeds
Solution Approach 2:
The patent optimizes specific geometric parameters including the ratio of the first radius of curvature to the second radius of curvature, the axial location of the bulge, and the radial extent of the flowpath curve. These parameter optimizations are designed to minimize drag forces while enabling cruise speeds above Mach 0.72
2Object-affected harmful factors
If the housing external surface is shaped with optimized flowpath curves to reduce drag, then wave drag and frictional drag are minimized, but the manufacturing complexity increases
Solution Approach 1:
The patent applies different curvature characteristics to different regions of the housing external surface. The flowpath curve includes a bulge region with a first radius of curvature and a trough region with a second radius of curvature, where each region is optimized for its specific function in managing airflow, thereby reducing overall drag while maintaining manufacturability through localized geometric features
3Productivity
If conventional housing shapes are used, then manufacturing is easier, but thrust production efficiency decreases due to energy losses and swirl
Solution Approach 1:
The curved flowpath surfaces with optimized radii of curvature reduce flow separation and minimize swirl and vortices in the air leaving the fan. This improves thrust production efficiency by converting more of the input power into useful thrust while reducing energy losses
Solution Approach 2:
By optimizing the geometric parameters of the flowpath curve including the ratio of radii of curvature and axial locations, the system maximizes thrust production efficiency and minimizes energy losses in the airflow
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 design enables aircraft to achieve high subsonic cruise flight speeds with improved efficiency, reducing wave drag and maintaining low pressure loss and drag, thus enhancing fuel efficiency and performance.
Implementation Method 1
shockwave-related drag forces (e.g., wave drag) on external surfaces of the aircraft propulsion system
Implementation Method 2
frictional drag forces on external surfaces of an aircraft propulsion system
Implementation Method 3
losses in energy in air as it enters and passes through the fan
Implementation Method 4
a fan of an aircraft propulsion system produces thrust by accelerating air passing through the fan
Implementation Method 5
velocity contributions that do not contribute to thrust (such as swirl and vortices in the air leaving the fan)
Data Source
AI summary
Apparatuses and systems are provided herein for unducted propulsion systems. The system includes a forward housing for high efficiency for high subsonic sustained flight. A plurality of blades are affixed to the forward housing, wherein the forward housing defines a flowpath curve extending from the forward-most end of the forward housing through the axial extent of a forward blade root. The flowpath curve is described by an axial direction parallel to an axis of rotation and a radius from the axis of rotation. The flowpath curve includes a first point having a first radius where the radius reaches a maximum forward of the forward blade root and a second point aft of the first point having a second radius where the radius stops decreasing. The ratio of the first radius to the second radius is greater than or equal to 1.029.