Turbojet Temperature Probe in Intermediate Casing
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Solution Overview
Problem
Existing temperature probes in two-spool bypass turbojets for measuring the temperature T25 at the inlet to the high-pressure compressor are complex, costly, and create flow disturbances due to their design, require de-icing functions and external power, and are susceptible to aerodynamic stresses.
Innovation Solution
A device with a temperature probe housed within a connection arm of the intermediate casing, which directs the primary stream gas into the secondary stream, eliminating the need for a casting, de-icing function, and reducing aerodynamic stress, while maintaining accurate temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature probe with inertial separator and casting is used in the primary stream flow passage, then the probe is protected against moisture, water, ice, sand and other foreign bodies, but the casting becomes complex to fabricate and the probe cost increases
Solution Approach 1:
The invention extracts the temperature probe from direct exposure to the primary stream by housing it within the protected environment of the intermediate casing. The probe remains inside the casing while still measuring the primary stream temperature through the casing wall, eliminating the need for complex protective castings.
Solution Approach 2:
The intermediate casing serves multiple functions: it provides structural support for the turbojet engine, houses the temperature probe, and acts as a protective enclosure. This multi-functionality eliminates the need for separate protective castings around the probe.
2Measurement precision
If a temperature probe with inertial separator is placed in the primary stream flow passage, then temperature measurement is enabled, but the probe creates a wake that disturbs the flow into the high-pressure compressor
Solution Approach 1:
The invention extracts the temperature probe from the primary stream flow path by housing it within the intermediate casing. The probe measures temperature through the casing wall without protruding into the flow, thereby eliminating wake formation and flow disturbance to the high-pressure compressor.
3Reliability
If a temperature probe with de-icing function is used, then ice formation is prevented, but external electrical power supply and switch relay are required
Solution Approach 1:
The invention extracts the temperature probe from the harsh primary stream environment by housing it within the intermediate casing, which provides a more benign environment that reduces ice formation risk. This eliminates the need for active de-icing systems and their associated electrical components.
4Measurement precision
If a temperature probe is placed directly in the primary stream flow passage, then temperature measurement is achieved, but the probe is subjected to aerodynamic stresses at high frequencies
Solution Approach 1:
The invention extracts the temperature probe from direct exposure to high-frequency aerodynamic stresses by housing it within the intermediate casing. The probe remains in a protected environment while still measuring temperature through the casing wall, eliminating the need for the probe to withstand extreme aerodynamic loads.
5Reliability
If a temperature probe with heater resistance is used, then ice formation is prevented, but the casting becomes complex and cost increases
Solution Approach 1:
The invention extracts the temperature probe from direct exposure to icing conditions by housing it within the intermediate casing. This protected environment eliminates the need for heater resistance and complex manufacturing processes, simplifying production while maintaining reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution simplifies the probe design, reduces costs, minimizes flow disturbances, eliminates the need for external power, and protects the probe from aerodynamic stresses, enabling reliable and efficient temperature T25 measurement.
Implementation Method 1
at least one air outlet orifice for leading to a zone of the turbojet in which the surrounding pressure is less than the pressure in the primary stream flow passage at the inlet of the compressor
Data Source
AI summary
A device for measuring a compressor inlet temperature in a primary stream flow passage of a bypass turbojet. The device includes an airtight hollow structure forming a connection arm of an intermediate casing of the turbojet and configured to pass radially through a flow passage for the primary stream and a flow passage for a secondary stream of the turbojet, the connection arm including at least one inlet air orifice opening out into the primary stream flow passage at an inlet of a compressor and at least one air outlet orifice leading to a zone of the turbojet in which surrounding pressure is less than pressure in the primary stream flow passage at the inlet of the compressor; and a temperature probe having its sensitive element arranged inside the connection arm.