scholarly journals Closure to “Discussion of ‘Theoretical Basis for Extrapolation of Calibration Data of PTC 6 Throat Tap Nozzles’ and ‘A Method for the Extrapolation of Calibration Data of PTC 6 Throat Tap Nozzles’” (1991, ASME J. Eng. Gas Turbines Power, 113, pp. 239–240)

1991 ◽  
Vol 113 (2) ◽  
pp. 240-241
Author(s):  
J. W. Murdock ◽  
D. R. Keyser
Keyword(s):  
Gas Turbines ◽  
Theoretical Basis ◽  
Calibration Data

Theoretical Basis for Extrapolation of Calibration Data of PTC 6 Throat Tap Nozzles

1991 ◽  
Vol 113 (2) ◽  
pp. 228-232 ◽  
Author(s):  
J. W. Murdock ◽  
D. R. Keyser
Keyword(s):  
Boundary Layer ◽  
Theoretical Basis ◽  
Reynolds Numbers ◽  
Boundary Layer Theory ◽  
Calibration Data ◽  
Maximum Difference ◽  
Calibration Laboratory

Equations for the extrapolation of calibration data for ASME/PTC 6 throat tap nozzles are derived from boundary layer theory. The results match published coefficients with a maximum difference of +0.03 percent. It is also shown that the effects of transition in the boundary layer extend to throat Reynolds numbers in excess of 10,000,000, far beyond the capacity of any known calibration laboratory. The present PTC 6 requirement that calibration data must be in the fully turbulent range cannot be met with current facilities.

CTV: A New Method for Mapping a Full Scale Prototype of an Axial Compressor

1996 ◽  
Author(s):  
Vasco Mezzedimi ◽  
Pierluigi Nava ◽  
Dave Hamilla
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Theoretical Basis ◽  
Axial Compressor ◽  
Heavy Duty ◽  
Test Vehicle ◽  
Testing Method ◽  
Area Reduction ◽  
Speed Range ◽  
Compressor Inlet

The full mapping of a new gas turbine axial compressor at different speeds, IGV settings and pressure ratios (from choking to surge) has been performed utilizing a complete gas turbine with a suitable set of modifications. The main additions and modifications, necessary to transform the turbine into the Compressor Test Vehicle (CTV), are: - Compressor inlet throttling valve addition - Compressor discharge bleed valve addition - Turbine 1st stage nozzle area reduction - Starting engine change (increase in output and speed range). This method has been successfully employed on two different single shaft heavy-duty gas turbines (with a power rating of 11MW and 170 MW respectively). The paper describes the theoretical basis of this testing method and a specific application with the above mentioned 170 MW machine.

Thermal History Coatings: Part I — Influence of Atmospheric Plasma Spray Parameters on Performance

2020 ◽  
Author(s):  
Silvia Araguás-Rodríguez ◽  
Marta Ferran-Marqués ◽  
Christopher C. Pilgrim ◽  
Spyros Kamnis ◽  
Jörg P. Feist ◽  
...  
Keyword(s):  
Thermal History ◽  
Gas Turbines ◽  
Gas Flow ◽  
Measurement Techniques ◽  
Luminescent Properties ◽  
Atmospheric Plasma ◽  
Steady Increase ◽  
Spray Parameters ◽  
Calibration Data ◽  
Particle Exposure

Abstract Firing temperatures in gas turbines have seen a steady increase over the years to allow for higher engine efficiencies and a decrease in hazardous emission levels. Conversely, these harsh conditions severely challenge the component lifetime, requiring a trade-off during the design process. Thus, it is crucial to understand temperature distribution across the majority of a component surface (>80%) to verify the design and component durability. While a range of temperature measurement techniques are available, these are primarily focused on lower temperatures, exhibit low durability (thermal paints), require line of sight (pyrometers), are destructive (thermal crystals) and only provide point measurements (thermocouples, thermal crystals). To overcome this challenge, Sensor Coating Systems (SCS) have developed Thermal History Coatings (THCs) to measure temperature profiles in the 900–1600°C range. This new temperature profiling capability records the past maximum exposure temperature in such a way that it can be determined once the component has already cooled down. THCs are comprised of oxide ceramics deposited via Atmospheric Plasma Spraying (APS) to create a robust coating. APS deposition employs several variable parameters; spray settings such as gun power, gas flow or scan rate can affect the particle exposure and thus, the microstructure of the coating and its temperature sensing performance. This two-part paper covers the THCs principles and demonstrates their capabilities for high-temperature applications. This first part shows, for the first time, the influence of APS parameters on luminescent measurements due to changes in the material microstructure. Extensive calibration data was used to develop a new model to relate the APS spray parameters to the luminescent properties in the as-deposited condition and consequent performance as a temperature sensor. The powder composition and the power and gas flow used during deposition were found to be the most influential parameters. The model identified the optimum spray parameters and was used to demonstrate THCs can achieve measurements in excess of 1600°C.

A Method for the Extrapolation of Calibration Data of PTC 6 Throat Tap Nozzles

1991 ◽  
Vol 113 (2) ◽  
pp. 233-239 ◽  
Author(s):  
J. W. Murdock ◽  
D. R. Keyser
Keyword(s):  
Theoretical Basis ◽  
Single Point ◽  
Reynolds Numbers ◽  
Calibration Data ◽  
Precise Method ◽  
Numerical Examples ◽  
Coefficient Of Discharge

This paper describes a precise method for extrapolating the coefficient of discharge of PTC 6 throat tap nozzles using all or most of the calibration data. The theoretical basis for this method is described in a parallel paper [3]. Numerical examples are given using actual calibration data to describe this method. Because this method permits the use of all calibration data at or above Reynolds numbers of 1,000,000, it is a clear improvement over the PTC 6-1976 method, which permits only the highest single point.

Optical Nondestructive Condition Monitoring of Thermal Barrier Coatings

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
A. L. Heyes ◽  
J. P. Feist ◽  
X. Chen ◽  
Z. Mutasim ◽  
J. R. Nicholls
Keyword(s):  
Rare Earth ◽  
Thermal Barrier Coatings ◽  
Condition Monitoring ◽  
Gas Turbines ◽  
Thermal Protection ◽  
Uv Light ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Calibration Data ◽  
Barrier Coatings

This paper describes recent developments of the thermal barrier sensor concept for nondestructive evaluation (NDE) of thermal barrier coatings (TBCs) and online condition monitoring in gas turbines. Increases in turbine inlet temperature in the pursuit of higher efficiency will make it necessary to improve or upgrade current thermal protection systems in gas turbines. As these become critical to safe operation, it will also be necessary to devise techniques for online condition monitoring and NDE. The authors have proposed thermal barrier sensor coatings (TBSCs) as a possible means of achieving NDE for TBCs. TBSCs are made by doping the ceramic material (currently yttria-stabilized zirconia (YSZ)) with a rare-earth activator to provide the coating with luminescence when excited with UV light. This paper describes the physics of the thermoluminescent response of such coatings and shows how this can be used to measure temperature. Calibration data are presented along with the results of comparative thermal cycle testing of TBSCs, produced using a production standard air plasma spray system. The latter show the durability of TBSCs to be similar to that of standard YSZ TBCs and indicate that the addition of the rare-earth dopant is not detrimental to the coating. Also discussed is the manufacture of functionally structured coatings with discreet doped layers. The temperature at the bond coat interface is important with respect to the life of the coating since it influences the growth rate of the thermally grown oxide layer, which in turn destabilizes the coating system as it becomes thicker. Experimental data are presented, indicating that dual-layered TBSCs can be used to detect luminescence from, and thereby the temperature within, subsurface layers covered by as much as 500 μm of standard TBC material. A theoretical analysis of the data has allowed some preliminary calculations of the transmission properties of the overcoat to be made, and these suggest that it might be possible to observe phosphorescence and measure temperature through an overcoat layer of up to approximately 1.56 mm thickness.

Optical Non-Destructive Condition Monitoring of TBC’s

2007 ◽  
Author(s):  
A. L. Heyes ◽  
J. P. Feist ◽  
X. Chen ◽  
Z. Mutasim ◽  
J. R. Nicholls
Keyword(s):  
Rare Earth ◽  
Thermal Barrier Coatings ◽  
Condition Monitoring ◽  
Gas Turbines ◽  
Thermal Protection ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Calibration Data ◽  
Barrier Coatings ◽  
Non Destructive

The paper describes recent developments of the thermal barrier sensor concept for non-destructive evaluation (NDE) of thermal barrier coatings and on-line condition monitoring in gas turbines. Increases in turbine inlet temperature in pursuit of higher efficiency will make it necessary improve or upgrade current thermal protection systems in gas turbines. As these become critical to safe operation it will also be necessary to devise techniques for online conditions monitoring and NDE. The authors have proposed thermal barrier sensor coatings (TBSC) as a possible means of achieving NDE for thermal barrier coatings. TBSC’s are made by doping the ceramic material (currently yttria stabilised zirconia) with a rare earth activator to provide the coating with luminescence when excited with UV light. The paper describes the physics of the thermo-luminescent response of such coatings and shows how this can be used to measure temperature. Calibration data is presented along with the results of comparative thermal cycle testing of TBSC’s, produced using a production standard APS system. The latter show the durability of TBSC’s to be similar to that of standard YSZ TBC’s and indicate that the addition of the rare-earth dopant is not detrimental to the coating. Also discussed is the manufacture of functionally structured coatings with discreet doped layers. The temperature at the bond coat interface is important with respect to the life of the coating since it influences the growth rate of the thermally grown oxide layer which in turn destabilises the coating system as it becomes thicker. Experimental data is presented indicating that duallayered TBSC’s can be used to detect luminescence from, and thereby the temperature within, sub surface layers covered by as much as 500μm of standard TBC material. A theoretical analysis of the data has allowed some preliminary calculations of the transmission properties of the overcoat to be made and these suggest that it might be possible to observe phosphorescence and measure temperature through an overcoat layer of up to approximately 1.56mm thickness.

Video-Enhanced Microscopy--Better Visibility of Plant Cell Structures

1982 ◽  
Vol 40 ◽  
pp. 182-185
Author(s):  
N.S. Allen ◽  
R.D. Allen
Keyword(s):  
Diffraction Pattern ◽  
Theoretical Basis ◽  
Numerical Aperture ◽  
Gain Control ◽  
Control Unit ◽  
Camera Control ◽  
Variable Gain ◽  
Contrast Method ◽  
Fine Detail ◽  
Cell Structures

Various methods of video-enhanced microscopy combine TV cameras with light microscopes creating images with improved resolution, contrast and visibility of fine detail, which can be recorded rapidly and relatively inexpensively. The AVEC (Allen Video-enhanced Contrast) method avoids polarizing rectifiers, since the microscope is operated at retardations of λ/9- λ/4, where no anomaly is seen in the Airy diffraction pattern. The iris diaphram is opened fully to match the numerical aperture of the condenser to that of the objective. Under these conditions, no image can be realized either by eye or photographically. Yet the image becomes visible using the Hamamatsu C-1000-01 binary camera, if the camera control unit is equipped with variable gain control and an offset knob (which sets a clamp voltage of a D.C. restoration circuit). The theoretical basis for these improvements has been described.

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