Mechanical Iris Tip Clearance Control for Gas Turbines
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Solution Overview
Problem
Existing tip clearance control systems in gas turbine engines suffer from inefficiencies due to the use of bleed or bypass air, leading to reduced engine efficiency and worse specific fuel consumption.
Innovation Solution
A mechanical iris tip clearance control system utilizing an adjustable opening with a ring of abradable material, where the distance between the blade tip and the inner surface is adjusted by changing the diameter of the opening, allowing for real-time control without the need for bleed or bypass air, using a mechanical iris with iris leaves that pivot to adjust the opening size and an actuator to control the tip clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cooling air is piped from other engine stations to control thermal expansion and contraction of the engine shroud, then tip clearance is controlled, but engine efficiency is reduced and specific fuel consumption worsens
Solution Approach 1:
The invention extracts the harmful dependency on cooling air piping by introducing a mechanical iris device that directly mechanically adjusts the engine shroud position. This eliminates the need to pipe cooling air from other engine stations, thereby removing the associated energy losses while maintaining tip clearance control capability.
Solution Approach 2:
The invention replaces the thermal-based control system (using cooling air to induce thermal expansion/contraction) with a direct mechanical control system (the mechanical iris device). This substitution eliminates the inefficiencies of the thermal approach while achieving the same tip clearance control objective.
2Manufacturing precision
If cooling air is piped from other engine stations to control tip clearance, then tip clearance is adjusted, but specific fuel consumption increases
Solution Approach 1:
The invention removes the energy-consuming cooling air piping system and replaces it with a mechanical iris device that uses minimal energy for actuation. This extraction of the harmful thermal control mechanism directly improves specific fuel consumption while preserving tip clearance adjustment capability.
Solution Approach 2:
By substituting the thermal control mechanism with a mechanical iris device, the system eliminates the continuous energy consumption associated with piping cooling air through the engine. The mechanical system requires energy only for actuation, significantly reducing overall energy use and improving specific fuel consumption.
3Loss of energy
If a mechanical iris system is used for tip clearance control, then engine efficiency is improved, but device complexity increases
Solution Approach 1:
The mechanical iris device is segmented into multiple adjustable elements (iris leaves or segments) that can be independently positioned. This segmentation allows for precise control of the engine shroud position while keeping each individual segment relatively simple in design, thereby managing overall system complexity.
Solution Approach 2:
The mechanical iris device serves multiple functions: it controls tip clearance, provides real-time adjustment capability, and eliminates the need for complex cooling air piping systems. By consolidating these functions into a single device, the overall system complexity is managed despite the added mechanical components.
Data Source
AI summary
Systems and methods are provided that use a tip clearance control apparatus comprising a mechanical iris, where the tip clearance control apparatus controls a distance between a tip of a blade and a ring of abradable material positioned in an adjustable opening of the mechanical iris.