Split Flow Thrust Reverser Clamshell Doors
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Solution Overview
Problem
Current thrust reverser systems for jet engines suffer from inefficiencies in reverse thrust generation and noise attenuation, leading to reduced deceleration capabilities and rudder blanking issues for tail-mounted engines, which impairs directional control during reverse thrust.
Innovation Solution
The ULTRA QUIET SPLIT FLOW THRUST REVERSER system employs geometrically shaped clamshell doors with independent stiffening and longitudinal supports to divert exhaust flow, a mixer nozzle with perforations for noise reduction, and a mechanical linkage with high-strength compression springs and electric locking mechanisms to prevent inadvertent deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional clamshell doors are used with exhaust gases bouncing off at 83° angle, then the结构简单 (structure is simple), but the reverse thrust efficiency is low
Solution Approach 1:
The exhaust flow is segmented into two separate paths: one portion flows along the inner skin surface at 83° angle, while another portion is diverted through the duct channel between inner and outer skins. This segmentation of flow paths enables the system to achieve both the traditional bounce-off effect and the improved directional control for higher reverse thrust efficiency.
Solution Approach 2:
The invention adds a third dimension to the exhaust flow by creating a duct channel between the inner and outer door skins. This channel directs a portion of the exhaust flow in a different spatial direction (through the door structure itself) rather than just along the surface, thereby increasing the resultant reverse thrust vector.
2Force
If exhaust flow is directed at 83° angle for reverse thrust, then the reverse thrust component is maximized, but rudder blanking occurs reducing directional control
Solution Approach 1:
The exhaust flow is divided into two segments with different directions: one segment maintains the 83° angle for maximum reverse thrust, while the other segment is diverted through the duct channel to exit at a different angle. This segmentation allows the system to provide both strong reverse thrust and reduced rudder blanking simultaneously.
Solution Approach 2:
Different portions of the exhaust flow are given different directional qualities - the portion along the inner skin maintains high reverse thrust characteristics, while the portion through the duct channel provides directional control by exiting at a different angle. This local differentiation of flow properties resolves the contradiction between thrust and control.
3Object-affected harmful factors
If solid door surfaces are used for exhaust gas deflection, then the structural strength is sufficient, but noise attenuation is poor
Solution Approach 1:
The door structure incorporates a duct channel that allows exhaust gases to pass through the door structure itself rather than just deflecting off a solid surface. This porous-like flow path through the door increases turbulence and mixing, which enhances noise attenuation while the outer skin and stiffeners maintain structural integrity.
4Object-affected harmful factors
If exhaust gases are contained within a continuous tailpipe, then thrust leakage is prevented, but noise attenuation is reduced
Solution Approach 1:
The exhaust flow is segmented into contained and uncontained paths: one portion remains within the continuous tailpipe to prevent thrust leakage, while another portion is diverted through the duct channel in the door structure to increase noise attenuation through turbulence and mixing with ambient air.
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 enhances reverse thrust efficiency by up to three to six folds, reduces noise through increased airflow mixing, and minimizes rudder blanking, ensuring safer directional control during reverse thrust operations.
Implementation Method 1
The ULTRA QUIET SPLIT FLOW THRUST REVERSER SYSTEM clamshell doors are shaped to split and divert a portion of the engine exhaust flow upward in the duct channel formed between the inner and outer door skins while the remaining portion of the engine exhaust flow, flows upward along the outer surface of the inner skin at an angle of around 83°
Implementation Method 2
The ULTRA QUIET SPLIT FLOW THRUST REVERSER SYSTEM noise attenuation improvements aim at increasing the mixing and line of contact between the engine exhaust flow and surrounding ambient air
Implementation Method 3
Adding perforations to the wall of the tailpipe mixer can further enhance noise attenuation by eductor action between low static pressure engine exhaust gases and ambient air
Implementation Method 4
The fixed and movable fairings are also improved for noise abatement by increasing the contact line at the trailing edge between the engine exhaust gases and ambient surrounding air using scallops or chevrons
Implementation Method 5
The forward frame of the clamshell door can be machined as one solid piece or can be assembled from detailed parts joined together and can have some lightening holes for weight reduction. One of the lightening holes engages with a rolling wheel as described in the text or rolling body shape to lock the door in the stowed position
Data Source
AI summary
A thrust reverser system for jet aircraft comprising an exhaust tailpipe mounted to the turbine engine aft turbine flange and two clamshell doors, actuators and a locking system to prevent inadvertent deployment of the clamshell doors in-flight. Two improved design clamshell doors configurations, either one or a combination of both, mounted on either side of the top and bottom of the exhaust tailpipe, fitted with two patented design actuators mounted one on each side of the external sides of the tailpipe between the clamshell doors and the tailpipe, possibly in a depression in the tailpipe called blister, assuming them to be hydraulic actuators for discussion purposes. The actuators drive the clamshell doors using improved floating linkages loosely pivoted to the exterior of the exhaust tailpipe. The actuators are connected to the doors through mechanical linkages, to deploy the doors aft of the tailpipe exhaust area during deceleration after landing, diverting the exhaust gases forward to slow down the aircraft, and the actuators also drive two movable fairings during thrust reverser operation to enclose the reversed exhaust flow forward to prevent its impingement on the skin of the aircraft and provide a ram inlet area with the sides of the clamshell doors allowing ram air from the surrounding free stream to be scooped through the gap between the movable fairing and clamshell doors thereby provide cooling of the door surface in contact with the exhaust gases and mix with the engine exhaust gases in reverse thrust mode thereby augmenting reverse thrust mass flow and energy. The exhaust tailpipe can have a circular or any geometric exhaust section or in other configuration can be fitted in with a flow mixer with the surrounding ambient air to reduce shear noise resulting from the high velocity exhaust gases for noise attenuation. The flow mixer can also be perforated to allow for suction of ambient air by the lower static pressure engine exhaust gases to reduce shear noise and increase mixing and thrust. Two fixed fairings, above and below the tailpipe at the exit section can have perforations and also perforations on the movable fairings to educt surrounding air also to reduce shear noise between surrounding air and the engine exhaust flow during forward thrust based on SAE Aerospace Information Report AIR-1191 and method of calculation. Other configurations for the trailing edges of the fixed and movable fairings can have wavy contour lines to increase the contact area between the engine exhaust gases and the surrounding air to reduce shear noise as well. Fixed circular shape or rolling bodies, depicted as wheels for discussion purpose, but they can be of any shape, mounted on the top and bottom of the tailpipe at the forward end which get lodged in the upper and lower forward frames of the clamshell doors in the stow position to provide one of the mechanical locking systems. A second mechanical locking system is a high strength compression steel spring which is part of the linkages used to deploy and stow the clamshell doors, which at the end of the stow stroke is buckled to prevent the clamshell doors deploy mechanism from moving, thereby keeping the doors securely stowed. A third locking mechanism consisting of electrically actuated locks which engage the clamshell doors in the stow position and lock the movable fairings to prevent them from being entrained by the free stream during flight.