Turbojet Temperature Sensor Signal Correction
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Solution Overview
Problem
Temperature sensors in turbojet engines face challenges due to inertia-induced time lags, leading to malfunctions during rapid temperature variations, and existing correction techniques are costly and inaccurate, especially when time constants vary significantly.
Innovation Solution
A method for real-time estimation and correction of temperature measurement signals using digital modeling, error signal estimation, and adaptive filtering, which adjusts to the specific time constant of each sensor, eliminating the need for expensive wind tunnel testing and additional estimators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If temperature sensors with fixed time constants are used based on standard charts, then manufacturing cost is reduced, but measurement precision deteriorates when sensor time constants deviate from chart values
Solution Approach 1:
The patent implements a dynamic estimation method that continuously adapts the time constant value during engine operation based on actual sensor response characteristics. This allows the system to accommodate sensors with varying time constants without requiring expensive wind tunnel testing for each sensor, thus maintaining measurement precision while avoiding increased manufacturing costs.
Solution Approach 2:
The system performs self-calibration by estimating the sensor's time constant from its own measurement signal during normal operation. The estimation process uses the sensor's response to temperature changes to automatically determine its characteristic time constant, eliminating the need for external testing facilities and enabling the system to adapt to any sensor within the acceptable range.
2Measurement precision
If wind tunnel testing is performed for each sensor to determine time constant, then measurement precision is improved, but manufacturing cost increases significantly
Solution Approach 1:
Instead of physically testing each sensor in expensive wind tunnel facilities, the patent creates a virtual model of sensor behavior through mathematical estimation. The system copies the essential dynamic characteristics of the sensor by estimating its time constant from operational data, providing sufficient accuracy without requiring physical testing infrastructure.
Solution Approach 2:
The patent replaces the mechanical wind tunnel testing system with a computational estimation algorithm. Rather than using physical facilities to measure sensor characteristics, the system uses signal processing and mathematical models to extract time constant information from the sensor's operational response, dramatically reducing testing costs.
3Measurement precision
If additional estimators are added to estimate fluid flow rate for time constant calculation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing temperature measurement system multi-functional by enabling it to simultaneously perform both temperature measurement and time constant estimation using the same signal processing chain. The system extracts multiple pieces of information (temperature and dynamic characteristics) from the same sensor signal, eliminating the need for separate flow rate estimators or additional sensing devices.
Data Source
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AI summary
A method including digitally modelling a temperature measured by a sensor by using a modeled signal and estimating a lag error signal for the sensor from the modeled signal and a signal obtained by filtering the modeled signal, the filter having as a parameter an estimate of a time constant of the sensor, and correcting the measurement signal delivered by the sensor by the estimated lag error signal. The time constant of the sensor is estimated as a function of time from the measurement signal and the modeled signal.