GE Energy Infrastructure

About: GE Energy Infrastructure is a based out in . It is known for research contribution in the topics: Wind power & Turbine. The organization has 1954 authors who have published 1781 publications receiving 20200 citations.

Fracture Parameters for Natural Rubber under Dynamic Loading

Abstract: An experimental study was conducted to evaluate the tear energy of unfilled and 25 phr carbon black-filled natural rubber with varying loading rates. The variation of the tear energy with far-field sample strain rate between 0.01 to 10 s−1 was found to be different from tensile strip and pure shear specimens. Above a sample strain rate of 10 s−1, the tear energy calculated from either specimen was comparable. The differences in the tear energy derived from the tensile strip and pure shear specimens were attributed to differences in the local crack tip stress state and strengthening of the material due to strain-induced crystallisation. Both of these factors resulted in crack speeds 3–4 times higher in the pure shear specimen as compared to the tensile strip specimen. Finite element analysis (FEA) indicated that fracture would initiate at the crack tip either when the strain energy density approached the material toughness or when the maximum principal stress and strain approached the material tensile strength and fracture strain, respectively. It was concluded that these parameters would be better than the tear energy in predicting fracture of natural rubber under dynamic loading.

Efficient Uncertainty Quantification of Centrifugal Compressor Performance Using Polynomial Chaos

Abstract: This paper presents a fully automated procedure to estimate the uncertainty of compressor stage performance, due to impeller manufacturing variability. The methodology was originally developed for 2D stages, i.e., stages for which the impeller blade angle and thickness distribution are only defined at the hub end-wall. Here, we extend the procedure to general 3D stages, for which blade angle and thickness distributions can be prescribed independently at the shroud and hub endwalls. Starting from the probability distribution of the impeller geometrical parameters, 3D sample geometries are generated and 1D/2D aerodynamic models are created, which are used to predict the performance of each sample geometry. The original procedure used the Monte Carlo method to propagate uncertainty. However, this requires a large number of samples to compute accurate performance statistics. Here we compare the results from Monte Carlo, with those obtained using Sparse Grid Polynomial Chaos Expansion (PCE) and a Multidimensional Cubature Rule for uncertainty propagation. PCE has exponential convergence in the stochastic space for smooth functions, and the use of sparse grids mitigates the increase of sample points due to the increase in the number of uncertain parameters. The cubature rule has accuracy limitations, but sample points increase only linearly with the number of parameters. For a 3D stage, the probability distributions of the performance characteristics are computed, as well as the sensitivity to the design parameters. The results show that PCE and Multidimensional Cubature give similar results to MC computations, with a much lower computational effort.Copyright © 2014 by ASME

Control methods for power converters

Abstract: A method of operating a power converter arrangement, the power converter arrangement includes a dc link and a dc load/source, an active rectifier/inverter having dc terminals connected to the dc link and is adapted to provide a variable dc link voltage between a maximum and a minimum limits, an interleaved buck converter having a plurality of converter circuits connected between the dc link and the dc load/source, wherein each converter circuit includes a first switch, a second switch, and a reactor, the method including determining one or more null values of dc link voltage with reference to the voltage across the dc load/source, and if a null value of dc link voltage is between the maximum and the minimum limits, controlling the active rectifier/inverter to provide a dc link voltage that is substantially the same as the null value of dc link voltage.

High Frequency Life Testing of Stator Coil Insulation

Abstract: This paper focuses on the development of insulation systems for high-speed and hence high-frequency electric motors with multi-MW ratings. With the growing demand for variable speed applications, an increasing number of medium and high voltage (4-13.8 kV) motors are being powered by adjustable speed drives (ASD's). One aspect that must be understood during the design of the motor is the impact that the voltage waveform from the ASD may have on the stator insulation. Both high fundamental frequency components (300- 600 Hz), switching frequency components (low kHz range) and fast rise time transient voltages (in the mus range) from the ASD's can increase the thermal and electrical stresses on the insulation resulting in a reduction of the service life. To study the effect of these ASD's on an epoxy-mica based insulation system, accelerated life tests were performed at 60 Hz, 418 Hz and 10 KHz. The main purpose of this study was to determine if the number of 'electrical cycles' to failure was constant for a given system over the range of voltages and frequencies tested and to explore if low frequency testing could be used as a predictor of insulation system life at higher frequencies. This paper will present the test setup and procedure, as well as the analysis and interpretation of the data. An examination of the resulting relationship between applied voltage, frequency and life of the insulation system will include a discussion of the ageing mechanisms at the various test voltages and frequencies.