Gas Turbine Speed Control via Temperature-Corrected Spool Regulation

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Solution Overview

Problem

Conventional gas turbine engines face challenges in maintaining consistent rotational speed of low and high pressure spools across varying power demands, leading to inefficient power control and response times.

Innovation Solution

A control system that uses a single controller to independently manage fuel flow for the low pressure spool and inlet guide vane angle for the high pressure spool, maintaining the rotational speed of the low pressure spool constant and temperature-correcting the high pressure spool's speed to ensure consistent operation across power demand variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the rotational speed of the high pressure spool is allowed to vary with power demand, then the engine can deliver variable power output, but the rotational speed becomes unstable and response time deteriorates

Engineering Contradiction:

Improvepower outputVSAvoidrotational speed stability

Core Design Contradiction:

PowerVSSpeed

Solution Approach 1:

The patent applies parameter changes by temperature-correcting the high pressure spool rotational speed using inlet temperature measurements. The controller adjusts the corrected speed parameter Ng' based on actual temperature conditions, allowing the engine to maintain stable operation across varying power demands while compensating for thermal effects on rotational speed.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the rotational speed of the low pressure spool is allowed to vary with power demand, then the engine can adapt to different power requirements, but the power control becomes inefficient and response time increases

Engineering Contradiction:

Improvepower demand adaptationVSAvoidresponse time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent implements feedback control by continuously monitoring the low pressure spool rotational speed Np and comparing it against a desired constant value. The controller modulates fuel flow based on the speed difference, creating a closed-loop system that maintains constant Np regardless of power demand variations, thereby improving response time and control efficiency.

Inventive Principle:

Principle #23Feedback

3Power

If fuel flow is modulated to control the high pressure spool speed, then the power output can be adjusted, but the rotational speed stability and temperature control deteriorate

Engineering Contradiction:

Improvepower output controlVSAvoidinlet temperature control

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The patent applies segmentation by separating the control of high pressure spool speed and inlet guide vane angle into independent control loops. The controller independently manages fuel flow for speed control and inlet guide vane positioning for temperature control, allowing both parameters to be optimized simultaneously without interfering with each other's stability.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP2489859B1Free gas turbine with constant temperature-corrected gas generator speed

Publication Date: 2020.11.25 PRATT & WHITNEY CANADA CORP

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AI summary

A method of controlling a speed of a gas turbine engine (10,110) including a gas generator or high pressure spool (24,124) and a power turbine or low pressure spool (20,120) rotating independently from one another, including controlling a rotational speed of the gas generator spool according to a fixed relationship with respect to an outside air temperature throughout a variation of output power.