Active tip clearance control system for aircraft engine

The active tip clearance control system in aircraft engines adjusts the radial gap between turbine blades and the shroud using temperature-controlled cooling air, addressing performance losses and enhancing efficiency and thrust generation.

CA3302848A1Pending Publication Date: 2026-09-21PRATT & WHITNEY CANADA CORP
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Patent Information

Application Number
CA3302848
Authority / Receiving Office
CA · CA
Patent Type
Applications
Current Assignee / Owner
Priority Date
2025-02-26
Filing Date
2026-02-24
Publication Date
2026-09-21

AI Technical Summary

Technical Problem

Existing active tip clearance control systems in aircraft engines are limited in their ability to efficiently adjust the radial gap between turbine blades and the surrounding shroud under varying engine operating conditions, leading to performance losses due to leakage and thermal expansion.

Method used

An active tip clearance control system that utilizes two sources of cooling air at different temperatures, controlled by a sensor and valve system, to adjust the clearance between turbine blades and the shroud based on measured clearance values and engine conditions, minimizing or maximizing the gap as needed.

Benefits of technology

The system effectively maintains optimal tip clearance, improving engine performance and efficiency by reducing leakage and thermal growth, while also generating additional thrust by directing cooling air into the low pressure turbine.

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Abstract

An aircraft engine includes an annular gas path extending across a compressor and a turbine with a casing, a shroud and blades, a clearance defined between blade tips and the shroud. An active tip clearance control device directing a cooling airflow to the casing includes a first air source at a first temperature, a second air source at a second temperature greater than the first, a valve having first and second inlets connected to the sources and an outlet selectively connectible with the inlets. The outlet is fluidly connected to the casing to selectively direct the flow of cooling air from the first or second source. A sensor measures the clearance. A controller connected to the sensor receives a signal therefrom of a measured clearance, and generates commands causing the valve to open to the first or second source when the clearance is above or below a predetermined value.
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