Turbomachine blade monitoring system

1. A turbomachine blade monitoring system, comprising:

an eddy current proximity probe assembly, comprising:

an eddy current proximity probe having a probe tip;

a probe case disposed at least partially about the eddy current proximity probe;

a probe sheath at least partially disposed about the probe case, wherein the probe sheath is coupled to the probe case by a first threaded connection; and

a probe tip shroud disposed about a circumference of the probe tip, wherein the probe tip shroud is coupled to the probe case by a second threaded connection, the probe tip shroud is configured to fill a gap between the probe tip and a turbomachine casing when the eddy current proximity probe assembly is coupled to the turbomachine casing, and the probe tip shroud comprises a non-metallic material; and

a monitor coupled to the eddy current proximity probe assembly, wherein the monitor is configured to monitor an interval of elapsed time between passing of a first turbomachine blade and a second turbomachine blade based on a signal provided by the eddy current proximity probe, wherein the signal is indicative of a presence of the first turbomachine blade or the second turbomachine blade.

2. The system of claim 1 , comprising a signal driver coupled to the eddy current proximity probe with a probe cable, wherein the signal driver is configured to provide excitation signals to the eddy current proximity probe.

3. The system of claim 2 , comprising data acquisition circuitry coupled to the signal driver, where the data acquisition circuitry is configured to monitor an amplitude of a return signal generated by the eddy current proximity probe and associate each peak of the amplitude with a time stamp indicating a time of each peak.

4. The system of claim 1 , wherein the probe tip shroud abuts the probe sheath disposed about the eddy current proximity probe, wherein the probe tip shroud is configured to extend from the probe sheath to an inner wall of the turbomachine casing when the eddy current proximity probe is disposed within the turbomachine casing.

5. The system of claim 1 , wherein the non-metallic material comprises a composite material.

6. The system of claim 1 , wherein the eddy current proximity probe is configured to detect an arrival or a departure of the first turbomachine blade.

7. The system of claim 1 , wherein the eddy current proximity probe is configured to detect a clearance between an outer radial end of the first turbomachine blade and an inner wall of the turbomachine casing.

8. The system of claim 1 , comprising a controller configured to control at least one function of a turbomachine based on the interval of elapsed time, wherein the controller comprises the monitor configured to monitor the interval of elapsed time between passing of the first turbomachine blade and the second turbomachine blade based on the signal.

9. A system, comprising:

a turbomachine having a first blade and a second blade that rotate along a surface;

an eddy current proximity probe assembly, comprising:

an eddy current proximity probe having a probe tip configured to provide a signal indicative of an interval of elapsed time between passing of the first blade along the surface and passing of the second blade along the surface;

a probe case disposed at least partially about the eddy current proximity probe;

a probe sheath at least partially disposed about the probe case, wherein the probe sheath is coupled to the probe case by a first threaded connection; and

a probe tip shroud disposed about a circumference of the probe tip, wherein the probe tip shroud is coupled to the probe case by a second threaded connection, the probe tip shroud is configured to fill a gap between the probe tip and a turbomachine casing when the eddy current proximity probe assembly is coupled to the turbomachine casing, and the probe tip shroud comprises a non-metallic material; and

a controller configured to control at least one function of the turbomachine based on the interval of elapsed time.

10. The system of claim 9 , wherein turbomachine comprises a turbine or a compressor, and the first and second blades are turbine blades or compressor blades.

11. The system of claim 9 , wherein the non-metallic material comprises a composite material.

12. The system of claim 9 , wherein the probe tip shroud is a removable annular shroud.

13. A system, comprising:

an eddy current proximity probe assembly, comprising:

an eddy current proximity probe having a probe tip;

a probe case disposed at least partially about the eddy current proximity probe;

a probe sheath at least partially disposed about the probe case, wherein the probe sheath is coupled to the probe case by a first threaded connection; and

a probe tip shroud disposed about a circumference of the probe tip, wherein the probe tip shroud is coupled to the probe case by a second threaded connection, the probe tip shroud is configured to fill a gap between the probe tip and a turbomachine casing when the eddy current proximity probe assembly is coupled to the turbomachine casing, and the probe tip shroud comprises a non-metallic material.

14. The system of claim 13 , wherein a radial end of the probe tip shroud is generally flush with an inner wall of the turbomachine casing when the eddy current proximity probe assembly is disposed within an aperture of the turbomachine casing.

15. The system of claim 13 , comprising a blade monitoring system having the eddy current proximity probe assembly, wherein the blade monitoring system is configured to monitor a clearance between a rotary blade and a casing and/or the blade monitoring system is configured to monitor a health of a tip portion of the rotary blade.

16. The system of claim 9 , comprising a controller monitoring system configured to detect a deviation in the interval of elapsed time.