Turbofan Variable Exhaust Cooling via Bypass Splitter Shell
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbofan engines emit high-velocity, hot exhaust plumes during ground operations, posing safety risks to personnel and requiring complex and fuel-intensive diverter mechanisms to redirect exhaust away from personnel during Engine Running Operations (ERO).
Innovation Solution
The turbofan engine configuration includes a bypass splitter shell that splits the bypass flow into interstitial and peripheral flows, mixing the interstitial bypass flow with the core exhaust flow to produce a cooler and slower mixed exhaust flow, which is achieved by axially translating the bypass splitter shell between active and idle configurations using an actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional core exhaust diverter mechanisms are used to redirect hot exhaust away from personnel, then safety of ground personnel is improved, but device complexity and fuel consumption increase
Solution Approach 1:
The patent merges the bypass flow with the core exhaust flow in the mixed exhaust duct, combining two separate flow streams to create a cooler, slower mixed exhaust plume. This eliminates the need for separate diverter mechanisms by using the bypass flow itself to cool the hot core exhaust.
Solution Approach 2:
The bypass flow acts as an intermediary cooling medium between the hot core exhaust and the external environment. By introducing the cooler bypass flow into the exhaust stream, it mediates the temperature and velocity reduction without requiring complex mechanical diverters.
2Object-affected harmful factors
If heavy core exhaust diverter mechanisms are employed, then exhaust redirection is achieved, but fuel consumption increases due to added weight
Solution Approach 1:
The engine's own bypass flow, which would otherwise be discharged separately, is redirected to serve a dual purpose: maintaining the required thrust while simultaneously cooling the core exhaust. This self-service approach eliminates the need for additional fuel-consuming diverter mechanisms.
3Object-affected harmful factors
If complex exhaust diverter mechanisms are used, then exhaust safety is improved, but maintenance requirements increase
Solution Approach 1:
The patent extracts and eliminates the complex mechanical diverter mechanisms entirely by using the bypass flow mixing system. This removal of problematic components directly reduces maintenance requirements while maintaining safety through the inherent cooling effect of the bypass flow.
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 configuration reduces the temperature and speed of the exhaust flow, making it safer for ground personnel by producing a mixed exhaust flow that is significantly cooler and slower than the core exhaust flow, thereby eliminating the need for heavy and complex diverter mechanisms.
Implementation Method 1
The interstitial bypass duct is configured to direct the interstitial bypass flow into core exhaust flow from the core engine and into a mixed exhaust duct at least partially defined by an aft portion of the bypass splitter shell
Data Source
AI summary
Disclosed aircraft and turbofan engines have an active configuration (corresponding to flight, etc.) and an idle configuration (corresponding to ground idle). Turbofan engines comprise a core engine, a nacelle, a bypass duct therebetween, and a bypass splitter shell that extends at least partially between the nacelle and the core engine to define peripheral and interstitial bypass ducts. Bypass flow in the bypass duct splits into peripheral bypass flow and interstitial bypass flow. The relatively cool, slow interstitial bypass flow is directed into relatively hot, fast core exhaust flow from the core engine and into a mixed exhaust duct at least partially defined by the bypass splitter shell. The bypass splitter shell may be selectively positioned to increase (in the idle configuration) or to decrease (in the active configuration) the relative flow of the interstitial bypass flow, thereby cooling and/or slowing the mixed exhaust flow in the idle configuration.