# US 8,543,341 B2 · System and method for monitoring health of airfoils > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,543,341 B2 - Document ID: US8543341B2 - Status: Granted - Kind: B2 - Application number: 12/825,763 - Filed: 2010-06-29 - Published: 2011-12-29 - Granted: 2013-09-24 - Earliest claimed: 2010-06-29 - Assignees: General Electric Company - Applicants: Venkatesh Rajagopalan; Vivek Venugopal Badami; Rahul Srinivas Prabhu; Ajay Kumar Behera; Aninda Bhattacharya - Inventors: Venkatesh Rajagopalan; Vivek Venugopal Badami; Rahul Srinivas Prabhu; Ajay Kumar Behera; Aninda Bhattacharya - Web page: https://patentgrep.com/patent/US8543341B2 ## CPC - F01D 21/003: {Arrangements for testing or measuring (for measuring vibrations G01H)} - F05D 2260/80: Diagnostics - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A method for monitoring the health of one or more blades is presented. The method includes the steps of determining a delta TOA corresponding to each of the one or more blades based upon respective actual time of arrival (TOA) of the one or more blades, determining a normalized delta TOA corresponding to each of the one or more blades by removing effects of one or more operational data from the delta TOA, and determining a corrected delta TOA corresponding to each of the one or more blades by removing effects of reseating of the one or more blades from the normalized delta TOA. ## Claims ### Claim 1 A method for monitoring the health of one or more blades, comprising: determining a delta TOA corresponding to each of the one or more blades based upon respective actual time of arrival (TOA) of the one or more blades by a processing subsystem; determining one or more coefficients based upon one or more operational data by the processing subsystem; determining effects of the one or more operational data on the respective actual TOA by utilizing the one or more coefficients and the one or more operational data; determining a normalized delta TOA corresponding to each of the one or more blades by removing the effects of the one or more operational data from the delta TOA by the processing subsystem; and determining a corrected delta TOA corresponding to each of the one or more blades by removing effects of reseating of the one or more blades from the normalized delta TOA by the processing subsystem. ### Claim 2 (depends on 1) The method of claim 1, wherein determining the delta TOA comprises subtracting the respective actual TOA corresponding to the one or more blades from a respective expected TOA of the one or more blades. ### Claim 3 (depends on 2) The method of claim 2, wherein the respective expected TOA of the one or more blades is a mean of respective actual TOA of the one or more blades. ### Claim 4 (depends on 1) The method of claim 1, wherein removing the effects of the one or more operational data from the delta TOA comprises: subtracting the effects of the one or more operational data from the delta TOA resulting in the normalized delta TOA. ### Claim 5 (depends on 1) The method of claim 1, wherein determining the one or more coefficients based upon the one or more operational data comprises utilizing the following equation: ΔTOAk= AD where ΔTOAk is a delta TOA of a blade k, D is one or more portions of operational data and Ā is a coefficient. ### Claim 6 (depends on 4) The method of claim 4, wherein the one or more coefficients are determined when the one or more blades are operating for the first time after a start up. ### Claim 7 (depends on 1) The method of claim 1, further comprising determining a static deflection corresponding to each of the one or more blades by filtering the corrected delta TOA corresponding to each of the one or more blades. ### Claim 8 (depends on 1) The method of claim 1, wherein determining the corrected delta TOA comprises: determining a reseating offset corresponding to each of the one or more blades; and subtracting the reseating offset from the normalized delta TOA resulting in the corrected delta TOA. ### Claim 9 (depends on 8) The method of claim 8, wherein the reseating offset is determined when the one or more blades are operating at base load. ### Claim 10 (depends on 8) The method of claim 8, wherein the reseating offset is determined when the one or more blades are operating for the first time after a start up. ### Claim 11 (depends on 8) The method of claim 8, wherein determining the reseating offset comprises: retrieving one or more normalized delta TOA corresponding to each of the one or more blades; determining one or more corrected delta TOA utilizing the one or more normalized delta TOA; determining a first mean of the one or more normalized delta TOA; determining a second mean of the one or more corrected delta TOA; and subtracting the second mean from the first mean resulting in the reseating offset. ### Claim 12 (depends on 11) The method of claim 11, wherein the one or more normalized delta TOA is determined when the one or more blades are not operating in a transient state. ### Claim 13 (depends on 1) The method of claim 1, wherein the one or more operational data comprises an inlet guide vane (IGV) angle, an inlet temperature (CTIM), load, mass flow, discharge pressure, or combinations thereof. ### Claim 14 A system, comprising a processing subsystem that: determines a delta TOA corresponding to each of the one or more blades based upon respective actual time of arrival (TOA) of the one or more blades; determines one or more coefficients based upon one or more operational data; determines effects of the one or more operational data on the respective actual TOA by utilizing the one or more coefficients and the one or more operational data; determines a normalized delta TOA corresponding to each of the one or more blades by removing the effects of the one or more operational data from the delta TOA by the processing subsystem; and determines a corrected delta TOA corresponding to each of the one or more blades by removing effects of reseating of the one or more blades from the normalized delta TOA. ### Claim 15 (depends on 14) The system of claim 14 further comprising one or more sensors to generate signals that are representative of the respective actual TOA of the one or more blades. ### Claim 16 (depends on 14) The system of claim 14, further comprising an onsite monitor to generate the one or more operational data. ### Claim 17 (depends on 14) The system of claim 14, further comprising at least one data repository that stores static deflection, delta TOA, actual TOA, intermediate results, or combinations thereof. ### Claim 18 (depends on 1) The method of claim 1, further comprising: generating static deflection corresponding to the one or more blades based upon the corrected delta TOA; and determining the health of the one or more blades based upon the static deflection. ### Claim 19 (depends on 18) The method of claim 18, wherein determining the health comprises detecting one or more defects or cracks in the one or more blades.