scholarly journals Transient temperature measurements and modeling of IGBT's under short circuit

1998 ◽  
Vol 13 (1) ◽  
pp. 12-25 ◽  
Author(s):  
A. Ammous ◽  
B. Allard ◽  
H. Morel
Keyword(s):  
Short Circuit ◽  
Temperature Measurements ◽  
Transient Temperature

scholarly journals Wall Temperature Measurements in Gas Turbine Combustors With Thermographic Phosphors

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Patrick Nau ◽  
Zhiyao Yin ◽  
Oliver Lammel ◽  
Wolfgang Meier
Keyword(s):  
Gas Turbine ◽  
Wall Temperature ◽  
Gas Turbines ◽  
High Speed ◽  
Bluff Body ◽  
Temperature Measurements ◽  
Transient Temperature ◽  
High Time Resolution ◽  
Ceramic Surface ◽  
Precessing Vortex Core

Phosphor thermometry has been developed for wall temperature measurements in gas turbines and gas turbine model combustors. An array of phosphors has been examined in detail for spatially and temporally resolved surface temperature measurements. Two examples are provided, one at high pressure (8 bar) and high temperature and one at atmospheric pressure with high time resolution. To study the feasibility of this technique for full-scale gas turbine applications, a high momentum confined jet combustor at 8 bar was used. Successful measurements up to 1700 K on a ceramic surface are shown with good accuracy. In the same combustor, temperatures on the combustor quartz walls were measured, which can be used as boundary conditions for numerical simulations. An atmospheric swirl-stabilized flame was used to study transient temperature changes on the bluff body. For this purpose, a high-speed setup (1 kHz) was used to measure the wall temperatures at an operating condition where the flame switches between being attached (M-flame) and being lifted (V-flame) (bistable). The influence of a precessing vortex core (PVC) present during M-flame periods is identified on the bluff body tip, but not at positions further inside the nozzle.

scholarly journals Dynamic Identification of Thermodynamic Parameters for Turbocharger Compressor Models

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
R. D. Burke ◽  
P. Olmeda ◽  
J. R. Serrano
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer Coefficient ◽  
Sensitivity Study ◽  
Temperature Measurements ◽  
Transient Condition ◽  
Transient Temperature ◽  
Dynamic Identification ◽  
Industry Standard

A novel experimental procedure is presented which allows simultaneous identification of heat and work transfer parameters for turbocharger compressor models. The method introduces a thermally transient condition and uses temperature measurements to extract the adiabatic efficiency and internal convective heat transfer coefficient simultaneously, thus capturing the aerodynamic and thermal performance. The procedure has been implemented both in simulation and experimentally on a typical turbocharger gas stand facility. Under ideal conditions, the new identification predicted adiabatic efficiency to within 1% point1 and heat transfer coefficient to within 1%. A sensitivity study subsequently showed that the method is particularly sensitive to the assumptions of heat transfer distribution pre- and postcompression. If 20% of the internal area of the compressor housing is exposed to the low pressure intake gas, and this is not correctly assumed in the identification process, errors of 7–15% points were observed for compressor efficiency. This distribution in heat transfer also affected the accuracy of heat transfer coefficient which increased to 20%. Thermocouple sensors affect the transient temperature measurements and in order to maintain efficiency errors below 1%, probes with diameter of less than 1.5 mm should be used. Experimentally, the method was shown to reduce the adiabatic efficiency error at 90 krpm and 110 krpm compared to industry-standard approach from 6% to 3%. However at low speeds, where temperature differences during the identification are small, the method showed much larger errors.

scholarly journals Dynamic Identification of Thermodynamic Parameters for Turbocharger Compressor Models

2014 ◽  
Author(s):  
Richard Burke ◽  
Pablo Olmeda ◽  
José Ramón Serrano
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer Coefficient ◽  
Sensitivity Study ◽  
Temperature Measurements ◽  
Transient Condition ◽  
Transient Temperature ◽  
Dynamic Identification ◽  
Industry Standard

A novel experimental procedure is presented which allows simultaneous identification of heat and work transfer parameters for turbocharger compressor models. The method introduces a thermally transient condition and uses temperature measurements to extract the adiabatic efficiency and internal convective heat transfer coefficient simultaneously, thus capturing the aerodynamic and thermal performance. The procedure has been implemented both in simulation and experimentally on a typical turbocharger gas stand facility. Under ideal conditions, the new identification predicted adiabatic efficiency to within 1%point and heat transfer coefficient to within 1%. A sensitivity study subsequently showed that the method is particularly sensitive to the assumptions of heat transfer distribution pre and post compression. If 20% of the internal area of the compressor housing is exposed to the low pressure intake gas, and this is not correctly assumed in the identification process, errors of 7–15%points were observed for compressor efficiency. This distribution in heat transfer also affected the accuracy of heat transfer coefficient which increased to 20%. Thermocouple sensors affect the transient temperature measurements and in order to maintain efficiency errors below 1%, probes with diameter of less than 1.5mm should be used. Experimentally, the method was shown to reduce the adiabatic efficiency error at 90krpm and 110krpm compared to industry standard approach from 6% to 3%. However at low speeds, where temperature differences during the identification are small, the method showed much larger errors.

Time-Resolved Micro-Raman Thermometry for Microsystems in Motion

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
Justin R. Serrano ◽  
Sean P. Kearney
Keyword(s):  
Microelectromechanical Systems ◽  
Diagnostic Technique ◽  
Temperature Measurements ◽  
Transient Temperature ◽  
Raman Signal ◽  
Periodic Signal ◽  
Fast Time ◽  
Time Resolved ◽  
Microelectromechanical Devices ◽  
Reliable Temperature

Micro-Raman thermometry has been demonstrated to be a feasible technique for obtaining surface temperatures with micron-scale spatial resolution for microelectronic and microelectromechanical systems (MEMSs). However, the intensity of the Raman signal emerging from the probed device is very low and imposes a requirement of prolonged data collection times in order to obtain reliable temperature information. This characteristic currently limits Raman thermometry to steady-state conditions and thereby prevents temperature measurements of transient and fast time-scale events. In this paper, we discuss the extension of the micro-Raman thermometry diagnostic technique to obtain transient temperature measurements on microelectromechanical devices with 100 μs temporal resolution. Through the use of a phase-locked technique we are able to obtain temperature measurements on electrically powered MEMS actuators powered with a periodic signal. Furthermore, we demonstrate a way of obtaining reliable temperature measurements on micron-scale devices that undergo mechanical movement during the device operation.

Transient Temperature Measurement Errors in Heated Slabs for Thermocouples Located at the Insulated Surface

1961 ◽  
Vol 83 (4) ◽  
pp. 505-506 ◽  
Author(s):  
D. R. Burnett
Keyword(s):  
Temperature Measurement ◽  
Measurement Errors ◽  
Wire Diameter ◽  
Temperature Measurements ◽  
Transient Temperature ◽  
Slab Thickness ◽  
Cold Side ◽  
Thermocouple Wire

A method is developed for estimating the error in “cold side” transient temperature measurements of slabs heated at one surface which is due to conduction of heat away from the junction through a thermocouple wire. Results are presented for a range of slab thickness/wire diameter ratios.

Transient Temperature Measurements in the Contact Zone Between Brush Seals of Kevlar and Metallic Type for Bearing Chamber Sealing Using a Pyrometric Technique

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Michael Flouros ◽  
Martin Stadlbauer ◽  
Francois Cottier ◽  
Stephan Proestler ◽  
Stefan Beichl
Keyword(s):  
Contact Zone ◽  
Operating Conditions ◽  
Temperature Measurements ◽  
Transient Temperature ◽  
Labyrinth Seals ◽  
Brush Seal ◽  
Aero Engine ◽  
Rotating Surface ◽  
Brush Seals ◽  
Engine Bearing

For the past 25 years brush seal technologies have evolved into the aero engine designs and, more generally, into the gas turbine world, not only for sealing gas areas at different pressure levels but also for sealing gas/liquid environments. This is the case in an aero engine where the bearing chambers are sealed. Aero engine bearing chambers enclose oil lubricated components such bearings and gears. In order to avoid contamination of the turbo machinery through oil loss, air blown seals are used to retain the oil into the bearing chamber. Oil loss may cause coking or ignition with the probability of an uncontained destruction of rotating parts such as disks or blades. It may also cause contamination of the air conditioning system with oil fumes thus causing health problems to the passengers and crew from such exposure. The most widely known seals for bearing chamber sealing are the labyrinth seals, however, in recent years brush seals and carbon seals have also been used. The latter are contact seals; that is, they may be installed having zero clearance to the rotating part and lift during operation when their air side is pressurized. During this survey an actual aero engine bearing chamber was modified to run with brush seals in a simulating rig. Two types of brush seals were used: (a) with bristles made of Kevlar, and (b) bristles made of a metallic material. Both types were installed with an overlap to the rotor. The targets set were twofold: (a) to measure the transient temperatures in the rotor and particularly in the contact zone between the bristles and the rotor, and (b) to measure the air leakage through the seals at different operating conditions. In order to obtain the transient temperature measurements with high fidelity, a new pyrometric technique was developed and was applied for the first time in brush seals. This technique has enabled placement of the pyrometer into the bristle's pack of the seal adjacent to the rotating surface and it could record the frictional temperature evolution in the bristles/rotor contact zone during acceleration or deceleration of the rotor. Additionally, the air consumption of the seals was measured and was compared to the air consumption through the labyrinth seals. For the metallic brush seal, up to 80% of the required sealing air can be saved, which can result, in turn, into a reduction in fuel burned by up to 1%. Furthermore, a design simplification of the bearing chamber architecture can be achieved by taking into account the reduced air flow. Even though the rotor was accelerated to high speeds up to 19,500 rpm, the produced temperature overshoots in the seal/rotor contact zone have caused no deterioration in either the materials or the oil.

Bismuth magnetoresistive thermometry for transient temperature measurements in liquid helium

1981 ◽  
Vol 52 (11) ◽  
pp. 1697-1704 ◽  
Author(s):  
L. C. Brodie ◽  
Dipen N. Sinha ◽  
C. E. Sanford ◽  
J. S. Semura
Keyword(s):  
Liquid Helium ◽  
Temperature Measurements ◽  
Transient Temperature

Time-Resolved Micro-Raman Thermometry for Microsystems

2007 ◽  
Author(s):  
Justin R. Serrano ◽  
Sean P. Kearney
Keyword(s):  
Diagnostic Technique ◽  
Temperature Measurements ◽  
Transient Temperature ◽  
Periodic Signal ◽  
Fast Time ◽  
Time Resolved ◽  
Microelectromechanical Devices ◽  
Scale Temperature ◽  
Reliable Temperature ◽  
Micro Electromechanical System

Micro-Raman thermometry has demonstrated to be a feasible technique for obtaining micron-scale spatial resolution of microelectronic and micro-electromechanical system (MEMS) temperatures. However, the low intensities of the Raman signals emerging from the device under study force the need for prolonged data collection times in order to obtain reliable temperature information. This characteristic currently limits Raman thermometry to steady state conditions, and thereby prevents temperature measurements of transient and fast time-scale events. In this paper we discuss the extension of the micro-Raman thermometry diagnostic technique to obtain transient temperature measurements on microelectromechanical devices with 100 μs temporal resolution. Through the use of a phase-locked technique we are able to obtain temperature measurements on electrically-powered MEMS actuators powered with a periodic signal. Furthermore, we demonstrate a way of obtaining reliable micro-scale temperature measurements on devices that undergo mechanical movement during the device operation.

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