Engineering

Publication Search Results

Now showing 1 - 3 of 3
  • (2010) Alshroof, Osama; Forbes, Gareth Llewellyn; Randall, Robert Bond
    Conference Paper
    A recent research program has identified the possibility of using the analysis of casing wall pressures in the indirect measurement of gas turbine rotor blade vibration amplitudes. Analytical modelling of the casing wall pressures and reconstruction of rotor blade vibration amplitudes from the analysis of these simulated pressure signals have shown potential advantages over current non-contact rotor blade vibration measurement methods. However, the modelling made some fundamental assumptions about the casing wall pressure. One of the assumptions made was that the pressure at the blade tip is not significantly different from that measured across the clearance gap at the casing wall. This fluid-structure hypothesis is investigated in this paper. Unsteady computational fluid dynamic modelling of the flow conditions around the blade surface, combined with the blade structural motion, is performed numerically, and the distributions of the pressure across the rotor blade tip and casing clearance gap are investigated and reported.

  • (2010) Forbes, Gareth Llewellyn; Alshroof, Osama; Randall, Robert Bond
    Conference Paper
    A recent research program has identified the possibility of using the analysis of casing wall pressures in the direct measurement of gas turbine rotor blade vibration amplitudes. Currently the dominant method of non-contact measurement of gas turbine blade vibrations employs the use of a number of proximity probes located around the engine periphery measuring the blade tip (arrival) time (BTT). Despite the increasing ability of this method there still exist some limitations, viz: the requirement of a large number of sensors for each engine stage, sensitivity to sensor location, difficulties in dealing with multiple excitation frequencies and sensors being located in the gas path. Analytical modelling of the casing wall pressures and reconstruction of rotor blade vibration amplitudes from the analysis of these simulated pressure signals has shown significant improvement over current non-contact rotor blade vibration measurement limitations by requiring only a limited number of sensors and providing robust rotor blade vibration amplitude estimates in the presence of simulated measurement noise. However, this modelling was conducted with some fundamental assumptions about the casing wall pressures being made. One of these assumptions presumed that during blade motion the pressure profile around the rotor blades follows the blade’s motion while it oscillates around its equilibrium position. This assumption is investigated in this paper through the numerical modelling of the fully coupled two-way rotor blade motion and fluid pressure interaction.

  • (2010) Willems van Beveren, Laurens; Huebl, H.; Starrett, Robert; Morello, Andrea
    Conference Paper
    We demonstrate radio frequency (RF) readout of electrically detected magnetic resonance in phosphorus-doped silicon metal-oxide field-effecttransistors (MOSFETs), operated at liquid helium temperatures. For the first time, the Si:P hyperfine lines have been observed using radio frequency reflectometry, which is promising for high-bandwidth operation and possibly time-resolved detection of spin resonance in donor-based semiconductor devices. Here we present the effect of microwave (MW) power and MOSFET biasing conditions on the EDMR signals.