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  • 1
    Electronic Resource
    Electronic Resource
    High-frequency response heat-flux gauge (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 639-649 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A double-sided, high-frequency response heat-flux gauge has been developed which allows measurement of heat flux from dc to 100 kHz. The instrument is designed for heat-flux magnitudes ranging from one to several hundred kW/m2 at temperatures up to 400 °C and is independent of the test article material. The gauges consist of a metal film (1500 A(ring)) resistance thermometers sputtered on both sides of a thin (25 μm) polyimide sheet. The sheet, which can contain many gauges, is then adhesively bonded to a test article. The temperature difference across the polyimide is a direct measure of the heat flux at low frequencies, while a quasi-1D analysis is used to infer the high-frequency heat flux from the upper surface temperature history. The design criteria, construction and application techniques, and a novel, ratiometric calibration procedure are discussed in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138882
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    Paper (German National Licenses)
    Fulltext
  • 2
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    High‐frequency response heat‐flux gauge (1986)
    American Institute of Physics
    Details
    Publication Date: 1986-04-01
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by American Institute of Physics
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    PAPER CURRENT
  • 3
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    Optical Instrumentation for Temperature and Velocity Measurements in Rig Turbines (1998)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: Non-intrusive optical measurement techniques have been examined in the context of developing robust instruments which can routinely yield data of engineering utility in high speed turbomachinery test rigs. The engineering requirements of such a measurement are presented. Of particular interest were approaches that provide both velocity and state-variable information in order to be able to completely characterize transonic flowfields. Consideration of all of the requirements lead to the selection of particle image velocimetry (PIV) for the approach to velocity measurement while laser induced fluorescence of oxygen (O2 LIF) appeared to offer the most promise for gas temperature measurement. A PIV system was developed and demonstrated on a transonic turbine stage in the MIT blowdown turbine facility. A comprehensive data set has been taken at one flow condition. Extensive calibration established the absolute accuracy of the velocity measurements to be 3-5 %. The O2 LIF proved less successful. Although accurate for low speed flows, vibrational freezing of O2 prevented useful measurements in the transonic, 300-600 K operating range of interest here.
    Keywords: Optics
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Dynamic Control of Aerodynamic Instabilities in Gas Turbine Engines (1992)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: This lecture discusses the use of closed loop control at the component level to enhance the performance of gas turbine engines. The general theme is the suppression of flow instabilities (rotating stall and surge) through use of feedback, either actively or by means of the aeromechanical coupling provided by tailored structures. The basic concepts that underlie active control of turbomachinery instability, and their experimental demonstration, are first described for a centrifugal compressor. It is shown that the mechanism for stabilization is associated with damping of unsteady perturbations in the compression system, and the steady-state performance can thus remain virtually unaltered. Control of instability using a tailored structure is then discussed, along with experimental results illustrating the flow range extension achievable using this technique. A considerably more complex problem is presented by active control or rotating stall where the multi-dimensional features mean that distributed sensing and actuation are required. In addition, there are basic questions concerning unsteady fluid mechanics; these imply the need to resolve issues connected with identification of suitable signals as well as with definition of appropriate wave launchers for implementing the feedback. These issues are discussed and the results of initial successful demonstrations of active control of rotating stall in a single-stage and a three-stage axial compressor are presented. The lecture concludes with suggestions for future research on dynamic control of gas turbine engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AGARD, Steady and Transient Performance Prediction of Gas Turbine Engines; 20 p
    Format: text
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    NASA TECHNICAL REPORTS
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