Gas Turbine Speed Sensor Probe Aft Positioning
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Solution Overview
Problem
In gas turbine engines, particularly in two-spool designs, the challenge lies in accurately locating a speed sensor probe to detect over-speed conditions while addressing packaging concerns and ensuring proper detection of engine events that may cause decoupling of the compressor or fan drive gear system from the spool, which existing solutions fail to mitigate effectively.
Innovation Solution
The speed sensor probe is positioned axially aft of the compressor and fan drive gear system input coupling, fixed relative to the first spool, allowing it to detect rotational speed accurately and prevent over-speed conditions by communicating with a controller to adjust fuel supply, and includes a sensor target that rotates with the spool for precise speed measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the speed sensor probe is positioned forward of the first compressor to simplify packaging, then packaging concerns are addressed, but the probe cannot detect over-speed conditions caused by decoupling of the compressor or fan drive gear system from the spool
Solution Approach 1:
The speed sensor probe is positioned axially aft of the first compressor rather than forward, utilizing the axial dimension to achieve proper detection capability. This dimensional repositioning allows the probe to detect rotational speed of the spool assembly while avoiding the decoupling zone, resolving the contradiction between packaging constraints and detection reliability.
Solution Approach 2:
The probe position is strategically placed in an intermediate zone axially aft of the first compressor but forward of the second compressor, where it can monitor spool speed without being affected by decoupling events at the compressor or fan drive gear system interfaces.
2Reliability
If the speed sensor probe is positioned axially aft of the first compressor to detect over-speed conditions, then over-speed detection reliability is improved, but packaging space and assembly complexity are reduced
Solution Approach 1:
The probe mounting location on the spool assembly serves multiple functions: it enables over-speed detection, maintains proper alignment with the rotational axis, and facilitates assembly through standardized mounting interfaces. This multi-functional design reduces overall device complexity despite the aft positioning.
3Ease of manufacture
If the speed sensor probe is mounted stationary relative to the engine rather than the spool, then packaging and assembly are simplified, but the probe cannot accurately detect spool rotational speed
Solution Approach 1:
The speed sensor probe is mounted to rotate with the spool assembly, merging the probe's motion with the spool's rotation. This ensures the probe maintains a constant radial position relative to the spool while rotating at the same speed, enabling accurate speed detection. The merged motion eliminates measurement errors that would occur with a stationary mounting.
Solution Approach 2:
Instead of using a complex mechanical linkage to transmit rotational speed information to a stationary sensor, the probe itself is made to rotate with the spool, replacing the need for mechanical transmission mechanisms and simplifying the overall system while maintaining measurement accuracy.
Data Source
Figure 1~2
Figure 3
AI summary
A gas turbine engine includes a fan, a fan drive gear system coupled to drive the fan, a compressor section including a first compressor and a second compressor and a turbine section. The turbine section includes a first turbine coupled to drive a first spool, which is coupled at a first axial position to a compressor hub that is coupled to drive the first compressor. The first spool is also coupled at a second axial position to a fan drive input shaft that is coupled to drive the fan drive gear system. A second turbine is coupled through a second spool to drive the second compressor. A speed sensor probe is operable to determine a rotational speed of the first spool. The speed sensor probe is located axially aft of the first axial position and the second axial position.