Acoustic emission (AE) can be generated by a number of different fault conditions in pipes, including localized fluid-mechanical disturbances, such as local impingement or erosion, growing fatigue cracks or crack face rubbing, external impacts and leaks, each of which may have its own temporal and frequency characteristics. In this paper, a linear array of sensors is applied with the ultimate aim of locating and reconstituting the time-domain and frequency-domain signatures of AE sources in pipes. Experiments have been carried out with a simulated source on sections of line pipe and process pipe using a linear array. The acquired signals have two identifiable components and methods are demonstrated for separating these components automatically and determining their group velocities. A range of techniques, including a wavelet transform technique, a cross-correlation technique, and a filtering and thresholding technique are applied to obtain arrival times for various modes of the signal. Finally, methods are proposed for giving automatic source location in large length-diameter ratios with an accuracy of better than 5 per cent.

Scaled down models are widely used for experimental investigations of large structures due to the limitation in the capacities of testing facilities along with the expenses of the experimentation. The modeling accuracy depends upon the model material properties, fabrication accuracy and loading techniques. In the present work the Buckingham π theorem is used to develop the relations (i.e. geometry, loading and properties) between the model and a large structural element as that is present in the huge existing petroleum oil drilling rigs. The model is to be designed, loaded and treated according to a set of similitude requirements that relate the model to the large structural element. Three independent scale factors which represent three fundamental dimensions, namely mass, length and time need to be selected for designing the scaled down model. Numerical prediction of the stress distribution within the model and its elastic deformation under steady loading is to be made. The results are compared with those obtained from the full scale structure numerical computations. The effect of scaled down model size and material on the accuracy of the modeling technique is thoroughly examined

The present work analyzes, through a rigorous numerical investigation, the entropy generation due to viscous dissipation around a Wells turbine blade. Two-dimensional numerical models for four NACA airfoils were built and validated against experimental measurements under steady flow conditions. The models were used to assess the entropy generation for flows achieving 10o angle of attack. It was found that the entropy generation around the NACA0015 airfoil blade is less by approximately 12% than the entropy generation around NACA0012, NACA0020 and NACA0021 airfoils. Then, the NACA0015 and NACA0021 airfoils were simulated under different flow conditions (i.e. Reynolds number and angle of attack). The results were discussed in the light of Wells turbine performance objectives

In arid regions, such as the North African desert, sandstorms impose considerable restrictions on horizontal axis wind turbines (HAWTs), which have not been thoroughly investigated. This paper examines the effects of debris flow on the power generation of the HAWT. Computational Fluid Dynamics (CFD) models were established and validated to provide novel insight into the effects of debris on the aerodynamic characteristics of NACA 63415. To account for the change in the chord length and Reynolds number along the span of the blade and the 3D flow patterns, the power curves for a wind turbine were obtained using the Blade Element Momentum (BEM) method. We present a novel coupled application of the neural network, CFD, and BEM to investigate the erosion rates of the blade due to different sandstorm conditions. The proposed model can be scaled and developed to assist in monitoring and prediction of HAWT blade conditions. This work shows that HAWT performance can be significantly diminished due to the aerodynamic losses under sandstorm conditions. The power generated under debris flow conditions can decrease from 10 to 30% compared to clean conditions.