Experience With Gas Path Analysis for On-Wing Turbofan Condition Monitoring

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Michel L. Verbist ◽  
Wilfried P. J. Visser ◽  
Jos P. van Buijtenen
Keyword(s):  
Path Analysis ◽  
Condition Monitoring ◽  
Operating Conditions ◽  
Performance Data ◽  
Test Rig ◽  
Substantial Cost ◽  
Substantial Cost Saving ◽  
Turbofan Engine ◽  
Monitoring Information

Gas path analysis (GPA) is an effective method for determination of turbofan component condition from measured performance parameters. GPA is widely applied on engine test rig data to isolate components responsible for performance problems, thereby offering substantial cost saving potential. Additional benefits can be obtained from the application of GPA to on-wing engine data. This paper describes the experience with model-based GPA on large volumes of on-wing measured performance data. Critical is the minimization of the GPA results uncertainty in order to maintain reliable diagnostics and condition monitoring information. This is especially challenging given the variable in-flight operating conditions and limited on-wing sensor accuracy. The uncertainty effects can be mitigated by statistical analysis and filtering and postprocessing of the large datasets. By analyzing correlations between measured performance data trends and estimated component condition trends errors can be isolated from the GPA results. The various methods assessed are described and results are demonstrated in a number of case studies on a large turbofan engine fleet.

Experience With Gas Path Analysis for On-Wing Turbofan Condition Monitoring

2013 ◽  
Author(s):  
Michel L. Verbist ◽  
Wilfried P. J. Visser ◽  
Jos P. van Buijtenen
Keyword(s):  
Path Analysis ◽  
Condition Monitoring ◽  
Operating Conditions ◽  
Performance Data ◽  
Test Rig ◽  
Substantial Cost ◽  
Substantial Cost Saving ◽  
Turbofan Engine ◽  
Monitoring Information

Gas path analysis (GPA) is an effective method for determination of turbofan component condition from measured performance parameters. GPA is widely applied on engine test rig data to isolate components responsible for performance problems, thereby offering substantial cost saving potential. Additional benefits can be obtained from the application of GPA to on-wing engine data. This paper describes the experience with model-based GPA on large volumes of on-wing measured performance data. Critical is the minimization of the GPA results uncertainty in order to maintain reliable diagnostics and condition monitoring information. This is especially challenging giving the variable in-flight operating conditions and limited on-wing sensor accuracy. The uncertainty effects can be mitigated by statistical analysis, and filtering and post-processing of the large datasets. By analyzing correlations between measured performance data trends and estimated component condition trends errors can be isolated from the GPA results. The various methods assessed are described and results are demonstrated in a number of case studies on a large turbofan engine fleet.

Gas Path Analysis on KLM In-Flight Engine Data

2011 ◽  
Author(s):  
Michel L. Verbist ◽  
Wilfried P. J. Visser ◽  
Jos P. van Buijtenen ◽  
Rob Duivis
Keyword(s):  
Path Analysis ◽  
Gas Turbine ◽  
Diagnostic Techniques ◽  
Operating Conditions ◽  
Performance Data ◽  
Analysis Tool ◽  
Incorrect Diagnosis ◽  
Wing Performance ◽  
Cell Data ◽  
Acceptance Tests

Gas-path-analysis (GPA) based diagnostic techniques enable health estimation of individual gas turbine components without the need for engine disassembly. Currently, the Gas turbine Simulation Program (GSP) gas path analysis tool is used at KLM Engine Services to assess component conditions of the CF6-50, CF6-80 and CFM56-7B engine families during post-overhaul performance acceptance tests. The engine condition can be much more closely followed if on-wing (i.e., in-flight) performance data are analyzed also. By reducing unnecessary maintenance due to incorrect diagnosis, maintenance costs can be reduced, safety improved and engine availability increased. Gas path analysis of on-wing performance data is different in comparison to gas path analysis with test cell data. Generally fewer performance parameters are recorded on-wing and the available data are more affected by measurement uncertainty including sensor noise, sensor bias and varying operating conditions. Consequently, this reduces the potential and validity of the diagnostic results. In collaboration with KLM Engine Services, the feasibility of gas path analysis with on-wing performance data is assessed. In this paper the results of the feasibility study are presented, together with some applications and case studies of preliminary GPA results with on-wing data.

A Study of Thermal Fatigue Life Prediction of Air-Cooled Turbine Blades

1978 ◽  
Author(s):  
T. Maya ◽  
I. Katsumata ◽  
M. Itoh
Keyword(s):  
Fatigue Life ◽  
Thermal Fatigue ◽  
Life Prediction ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Test Rig ◽  
Emission Method ◽  
Turbofan Engine ◽  
Thermal Fatigue Life ◽  
Bypass Ratio

One of the techniques for estimation of thermal fatigue life of air-cooled turbine blades is assured through coincidence between the results of experimental and analytical works. The actual turbine blades were tested on the test rig utilizing alternating hot and cold jet method under simulated operating conditions of the high-bypass ratio turbofan engine. Acoustic emission method is applied to detect the crack initiation of tested blades. The experimental data were analyzed statistically and the result was well close to the analytical value which was calculated using structural analysis program NASTRAN and universal slope relation.

Design and Experimental Verification of Mistuning of a Supersonic Turbine Blisk

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Pieter Groth ◽  
Hans Mårtensson ◽  
Clas Andersson
Keyword(s):  
Operating Conditions ◽  
Test Rig ◽  
Order Model ◽  
Unstable Region ◽  
Reduced Order ◽  
Flutter Boundary ◽  
Turbine Blisk ◽  
Random Patterns ◽  
System Mode

A rotor blisk of a supersonic space turbine has previously been designed to allow for free flutter to occur in an air test rig (Groth Mårtensson, and Edin, 2010, “Experimental and Computational Fluid Dynamics Based Determination of Flutter Limits in Supersonic Space Turbines,” 132(1), p. 011010). Flutter occurred at several operating conditions, and the flutter boundary for the test turbine was established. In this paper the rotor blisk is redesigned in order to inhibit flutter. The design strategy chosen is to introduce a mistuning concept. Based on aeroelastic analyses using a reduced order model a criterion for the required level of mistuning is established in order to stabilize the lower system modes. Proposals in literature suggest and analyze mistuning by varying blade mode frequencies in random patterns or by modifying blades in an odd-even pattern. Here a modification of sectors of the blisk is introduced in order to bring a sufficient split of the system mode frequencies. To verify that the redesigned blisk efficiently could inhibit flutter, an experiment similar to that in the work of Groth et al. is performed with the mistuned rotor blisk. By running the redesigned blisk at operating conditions deep into the unstable region of the tuned blisk, it is demonstrated that a relative low level of mistuning is sufficient to eliminate rotor flutter.

Determination of Rheological Parameters for Several Lubricants Applied in the High-Speed and High-Pressure Bearings

2011 ◽  
Vol 55-57 ◽  
pp. 1407-1411
Author(s):  
Yan Shuang Wang
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Operating Conditions ◽  
Lubricating Oil ◽  
Rheological Parameters ◽  
Test Rig ◽  
Lubricating Grease ◽  
Shear Elastic Modulus ◽  
Limiting Shear Stress

Traction coefficients of several domestic lubricants in various operating conditions were measured on a self-made test rig. The equations for calculating the average values of limiting shear stress and shear elastic modulus of the lubricants applied in the high-speed and high-pressure bearings were advanced. The example calculations for one lubricating oil and two lubricating grease were then made. The results show that the regression precisions of the equations above are satisfied. The equations also adapt to the other lubricants in the same operating conditions.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

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