Fuselage Divot Geometry for Unducted Engine Inlet Airflow Control
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Solution Overview
Problem
Unducted turbine engines experience undesirable fuel consumption due to accelerated inlet airflow, leading to increased Thrust Specific Fuel Consumption (TSFC), which is not efficiently addressed by extending the pylon or using iterative design processes.
Innovation Solution
Incorporating a divot in the fuselage near the unducted turbine engine to control the inlet airflow speed, optimizing its geometric shape and location to match or reduce it to the freestream airflow speed, thereby reducing TSFC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pylon is extended to move the unducted turbine engine farther from the fuselage, then the inlet airflow acceleration is reduced, but the structural complexity and weight increase
Solution Approach 1:
The fuselage surface is modified locally by adding a divot at the specific location where the engine interfaces with the fuselage. This local geometric change alters the airflow characteristics in the gap between the engine and fuselage without requiring global structural changes or pylon extension, thereby reducing TSFC while maintaining structural simplicity.
2Loss of energy
If an iterative design process is used to optimize engine placement, then the TSFC is reduced, but the design time and complexity increase
Solution Approach 1:
The divot geometry is pre-designed and incorporated into the fuselage structure before engine installation. This preliminary design approach establishes the optimal airflow management configuration in advance, eliminating the need for iterative adjustments and reducing design time while achieving the desired TSFC reduction.
3Device complexity
If the engine is mounted closer to the fuselage to reduce structural issues, then the structural complexity decreases, but the inlet airflow acceleration increases leading to higher TSFC
Solution Approach 1:
The divot modifies the geometric parameters of the fuselage surface at the engine interface, changing the airflow path and velocity distribution in the gap region. This parameter change allows the engine to be mounted closer to the fuselage with reduced pylon structure while compensating for the increased airflow acceleration through geometric optimization, thereby maintaining acceptable TSFC levels.
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 divot effectively manages inlet airflow speed, improving engine performance by reducing TSFC and minimizing structural issues associated with extended pylons, thus enhancing overall aircraft efficiency.
Implementation Method 1
Unducted turbine engines experience undesirable fuel consumption due to accelerated inlet airflow
Data Source
AI summary
An aircraft comprising a fuselage and an unducted turbine engine. The fuselage having a divot with an upstream edge and a downstream edge. The divot is defined by a straight reference line having a length (L) and a maximum depth (h) relative to the straight reference line. The unducted turbine engine having an engine core, a nacelle, and a set of blades. A first flow ratio (FR1) is equal to:hL.