Axially Split Nozzle Liner for Gas Turbine Engines
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Solution Overview
Problem
Existing gas turbine engine nozzle liners face thermal and external stress challenges due to thermal gradients and external loads, with rivets typically loaded in tension and requiring additional structure for flow blocking, which is undesirable.
Innovation Solution
The liner is formed of two split plates along an axial span-wise flange, with rivets loaded in shear and abutting faces forming a flow blocker, eliminating the need for a separate flow blocker plate and reducing stress transfer between plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single liner plate is used to face combustion products, then the liner can provide continuous thermal protection, but thermal stresses and external loads concentrate on the same structure causing high stress transfer
Solution Approach 1:
The liner is divided into two separate plates (first liner plate and second liner plate) positioned at different axial locations. The first liner plate faces combustion products in the forward portion, while the second liner plate faces combustion products in the aft portion. This segmentation separates thermal stress zones from external load zones, reducing stress concentration and improving overall structural strength while maintaining continuous thermal protection through proper positioning and overlapping of the two plates.
2Reliability
If rivets are used to attach the liner to the flap structure, then secure attachment is achieved, but rivets are loaded in tension which is undesirable
Solution Approach 1:
Instead of using rivets in tension to attach the liner to the flap structure, the invention inverts the loading approach by using rivets in shear. The first and second liner plates are attached to the flap structure such that the rivets experience shear loads rather than tensile loads. This inversion of the typical rivet loading mode eliminates the undesirable tension loading while maintaining secure attachment, as shear loading is more favorable for rivet performance.
3Reliability
If a separate flow blocker plate is added to maintain pressure differential, then flow control is improved, but device complexity increases
Solution Approach 1:
The invention merges the flow blocker function with the liner structure itself. The first and second liner plates are configured to work together as an integrated flow blocking system. The liner plates maintain the pressure differential between forward and aft portions of the nozzle by their positioning and configuration, eliminating the need for a separate flow blocker plate. This integration reduces device complexity while maintaining the necessary flow control and pressure differential functions.
Data Source
AI summary
A convergent/divergent nozzle for a gas turbine engine includes liners that are attached to the convergent flaps and seals. The liner is formed of two separate plates. By splitting the liner into two separate plates, a thermal break is provided between the two. Thermal stresses on a downstream plate are not as readily transferred to an upstream plate. External stresses on the upstream plate are not transferred as readily to the downstream plate. The two liner plate portions, and a separate backing plate all have faces that abut and are riveted together. These faces provide a flow blocker to maintain a lower pressure downstream of the flow blocker.