Gas Turbine Engine Area Ratio for Drag Reduction
Solution Overview
Problem
Scaling up gas turbine engine components without proportionally scaling other parameters can lead to increased drag and installation difficulties, affecting aircraft performance and requiring adjustments to engine dimensions to reduce drag and fit under the wing.
Innovation Solution
A gas turbine engine design with specific relative component dimensions, including a fan face area to turbine diameter ratio between 1.7 and 3, and a bypass to core exhaust nozzle pressure ratio between 1.1 and 2, optimized for reduced drag and improved installation, featuring a gearbox to drive the fan at a lower rotational speed than the core shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the overall size of a gas turbine engine is increased, then power output and thrust are improved, but the drag produced by the larger nacelle increases
Solution Approach 1:
The patent applies parameter changes by optimizing the engine area ratio (fan face area to turbine diameter ratio) to a specific range of 1.7 to 3. This dimensional parameter optimization allows the engine to achieve higher power output while controlling the nacelle size and drag characteristics, resolving the contradiction between power increase and drag reduction
2Power
If the overall size of a gas turbine engine is increased, then power output and thrust are improved, but installation difficulty increases
Solution Approach 1:
The patent optimizes the engine area ratio parameter to balance power output with installation feasibility. By constraining the ratio of fan face area to turbine diameter within 1.7 to 3, the engine achieves high power while maintaining compact proportions that facilitate installation under aircraft wings
Solution Approach 2:
The patent introduces a new dimensional relationship (engine area ratio) that connects fan size to turbine size, creating a scaling law that allows power increase while maintaining installation compatibility. This dimensional constraint enables the engine to scale up without proportionally increasing all dimensions
3Productivity
If the fan size is increased, then propulsive efficiency is improved, but the engine core dimensions become relatively smaller
Solution Approach 1:
The patent establishes an optimal engine area ratio range of 1.7 to 3, which defines the appropriate relationship between fan face area and turbine diameter. This parameter optimization allows the fan to be sufficiently large for high propulsive efficiency while ensuring the core dimensions remain appropriate for power generation
Data Source
AI summary
A gas turbine engine of an aircraft includes: an engine core having a turbine including a lowest pressure rotor stage, a turbine diameter, a fan including a plurality of fan blades extending from a hub, an annular fan face at a leading edge of the fan defining a fan tip radius at the fan face; wherein a downstream blockage ratio is defined as:theturbinediameteratanaxiallocationofthelowestpressurerotorstageadistancefromagroundplanetothewingand wherein an engine blockage ratio of:(2× the fan tip radius/the engine length)thedownstreamblockageratiois in the range from 2.5 to 4.