Indirect Shaft Power Determination in Gas Turbine Engines
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Solution Overview
Problem
Direct sensing of rotational shaft power in gas turbine engines is often impractical and cost-ineffective, necessitating alternative methods to control engine operation based on shaft power output.
Innovation Solution
A method involving the use of pressure and temperature signals to determine a value indicative of shaft power, utilizing a processing device to calculate a power setting parameter (PSP) through ratios of engine pressures and temperatures, which accounts for engine variations and provides a correction factor for wear, aging, and fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct sensing of shaft power is implemented, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses pressure and temperature sensors as intermediary measurements to indirectly determine shaft power. Instead of directly measuring power, the system measures pressure ratios (P2/P1, P3/P2) and temperature ratios (T2/T1, T3/T2) which serve as mediators to calculate the power setting parameter, thereby avoiding complex direct power sensing while maintaining measurement accuracy
Solution Approach 2:
The patent replaces mechanical/power-based direct measurement systems with thermodynamic parameter measurements. By substituting direct shaft power measurement with measurements of pressure and temperature ratios through the thermodynamic relationships, the system achieves power determination using simpler, more cost-effective sensing technologies
2Reliability
If engine-to-engine variation compensation is added, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent compensates for engine-to-engine variations by dynamically adjusting the power setting parameter calculation based on measured pressure and temperature ratios. The system changes the operational parameters (pressure ratios, temperature ratios) to account for differences in engine wear, aging, and fouling across individual engines, thereby maintaining reliable and accurate control without adding complex hardware
Data Source
AI summary
A gas turbine engine provides mechanical shaft power. Two parameters relating to engine operation are sensed that are representative of two different pressures, two different temperatures, or a pressure and a temperature associated with the engine. A value representative of the shaft power is determined during engine operation as a function of these two parameters. This value may be used for engine monitoring including making one or more adjustments to operational aspects of the engine, regulating/controlling engine function, and/or providing one or more power indicators.