Approximate solution of the internal problem for a turbulent boundary layer

The development of a turbulent boundary layer in an axisymmetric channel is analyzed with an an account of the mutual effects of the boundary layer and the core of the flow. The coordinates of the separation point, the coordinates of the junction, and other characteristics are found as functions of the Reynolds number and the channel geometry. A simple approximate method is proposed for calculating the boundary layer in a channel with an arbitrary curvilinear generatrix.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 18, No. 2, pp. 224–232, February, 1970.     

High-resolution alignment of sampled waveforms

Waveforms are often sampled faster than the Nyquist rate to obtain desired temporal resolution, even though, theoretically, oversampling adds no information and should not be necessary. This paper shows how high resolution can be achieved efficiently from data sampled at the Nyquist rate by working with coefficients of the Fourier-series expansion of the continuous interpolating waveform. Practical algorithms are presented for aligning and comparing waveforms, locating peaks, resolving superimpositions, and averaging overlapping waveforms. The algorithms prove to be more accurate, and to require fewer computations and less storage than techniques which employ continuous oversampling in many signal-processing applications, particularly template matching.     

Next Generation Thermal Barrier Coatings for the Gas Turbine Industry

The aim of this study is to develop the next generation of production ready air plasma sprayed thermal barrier coating with a low conductivity and long lifetime. A number of coating architectures were produced using commercially available plasma spray guns. Modifications were made to powder chemistry, including high purity powders, dysprosia stabilized zirconia powders, and powders containing porosity formers. Agglomerated & sintered and homogenized oven spheroidized powder morphologies were used to attain beneficial microstructures. Dual layer coatings were produced using the two powders. Laser flash technique was used to evaluate the thermal conductivity of the coating systems from room temperature to 1200 °C. Tests were performed on as-sprayed samples and samples were heat treated for 100 h at 1150 °C. Thermal conductivity results were correlated to the coating microstructure using image analysis of porosity and cracks. The results show the influence of beneficial porosity on reducing the thermal conductivity of the produced coatings.