Unusual vibration levels in rotating equipment usually result from unbalance, misalignment, mechanical looseness, propagating cracks and other sources of malfunctions. Appearance of these damages often excites destructive vibration amplitudes in rotor systems. Here, we focus on the induced vibration by propagating cracks in a rotating shaft. Detecting crack in its early phase of propagation might help in preventing further damage in the equipment as well as avoiding economic and human losses. The proper orthogonal decomposition (POD) is employed here as a crack detection technique for early damage detection and to identify the vibration signature of the cracked rotor response.
Anode baking is a critical step in production good quality of carbon anodes which are needed for aluminum production. The operational and geometrical parameters have significant influence on the anode baking furnace (ABF) performance and the resulting carbon anode quality. Numerical modelling is an imperative tool to investigate the effect of different parameters on the anode baking process. This study provides an overview of two different approaches employed in ABF modelling namely process modelling, and design modelling. Using process modelling, in a simplified manner, effect of several operational parameters on anode baking process are investigated. ABF design modelling concentrates on effect of different furnace design on baking process.
The current numerical study was necessitated because of a noninjuryproducing incident which occurred in a laboratory, where an autoclave exploded during an experiment titled: "AutoclaveAssisted Thermal Decomposition of Ammonium Tetrathiomolybdate and Carbon Nano Tubes Impregnation". The explosion was believed to have occurred because dimethyl sulfoxide (DMSO) was used in excess in the experiment and heated beyond its decomposition temperature. The aim of this current study therefore, is to investigate the effect of internal blast load on a pressure vessel made of stainless steel AISI 316L through finite element analysis. Numerical simulation using FEA was performed to better understand the true cause of failure of the pressure vessel. The result of the finite elementbased analysis that reasonably predicts the structural response and subsequent failure of the pressure vessel that was observed in the postincident investigation was presented.
Studying the dynamic behavior of cracked rotor systems has gained great interest in the literature. The extensive applications of heavyduty rotor dynamic systems in different industrial and aerospace rotating equipment could lead to crack catastrophic crackbased damages. Early detection of cracks in a cracked rotor in engineering practice is of significant importance to the safety, reliability and durability of large rotating machinery in service. The proposed backwardwhirl approach could help in detecting early crack damages in rotor system, by identifying a unique crack signature based on backward whirling analysis.
Trickle Bed Reactors used in the industry are significant to many processes. Understanding the hydrodynamics of the reactor allows a more efficient design and operation of the reactor. A smart sensor can provide a deeper knowledge of the operation in a reactor. This work investigates the flow regime and structure by analyzing the pressure fluctuation in the reactor. The method used involves using COMSOL as a software simulation. The simulation applies the Level Set Method and will track locally the wettability and pressure fluctuation. Eventually this data is to be validated with the smart sensor, hence the data to be measured by the smart sensors will provide a direct implication based on the analysis in this work.
This paper reports the simulation results of a guyedwire telecommunication tower located in a high flash density region and subjected to lightning strikes. This study is a response to incidents which occurred within few guyed towers in several locations in the region, and which resulted in severe damage to the electronics connected to the tower. This study intends to develop new protection measures for the guyed tower. The aim is to elucidate the possible reasons that led to such damage and recommend protection measures to improve LPS performance. Frequencydomain computations are carried out using frequencies representative of the typical lightning current. Hybrid approach is used to compute the GPR at the surface of conductors and inductively induced potentials and currents on adjacent coaxial cable. The results show that, large potential differences in excess of the maximum withstand level of the insulation may occur between the cable core and sheath.
Commercial earth resistivity test equipment have relatively narrow ranges of test frequency and magnitude of the injected current. A research program has been initiated to investigate the effect of varying the frequency and magnitude of the injected current on the measured apparent resistivity. Firstly, a conventional 'rollalong' soil resistivity survey was carried out over 6 survey lines at a designated test site at the Petroleum Institute using an ABEM Terrameter LS. A '2.5D' visual model was generated using VOXLER software. The results are analyzed and indicate clearly the presence of the water table. The proposed future work consisting of a systematic field test investigation into the effects of varying current magnitude and frequency is described and the associated computer simulations using numericalbased grounding software. The work is expected to lead to recommendations on optimized test parameters for commercial soil resistivity testers possible alternative improved test setups/techniques.
The power transformer is an expensive component in the power network and its failure can lead to power outages and significant financial loss, particularly at higher voltage levels. Frequency response analysis (FRA) is a recommended technique to diagnose transformer faults and particularly so for detecting mechanical displacements in windings and core. However, due to the complex way in which transformer electric parameters (inductance, capacitance, and resistance) are affected by such distortion, challenges remain in the correlation of FRA signature and fault type. Furthermore, FRA is influenced significantly by the adopted measurement method and practical test setup. This paper aims to investigate FRA responses of small laboratory test transformers measured using a standard 'IEEE' recommended method and with a proposed new generic test setup having additional current measurement points and using precision lockin amplifiers. The paper also presents results showing the effect of change in the magnitude of applied voltage levels.
Reliable operation of highvoltage power system equipment depends on the integrity of its insulation. During operation, the insulation is exposed to electrical, thermal, chemical and mechanical stresses. Electrical stress is the main factor. This occurs as partial discharges (PD) generated as a result of high electric field stress. Monitoring the insulation of electrical equipment in the highvoltage system is essential for maintenance purposes and for improving the reliability of the system. In this paper, an experimental study on the characteristics of surface discharge is presented. A test setup using a solid dielectric sample in a pointplane configuration was used to generate surface PD and the effect of voltage amplitude are examined. The results are analyzed using signal processing. Also, the electromagnetic fields radiated by this type of discharge were computed using the FDTD method. These may help in evaluating the sensor characteristics required for detecting surface discharges in practice.
A new model to describe the dynamics of the artificial gas lift systems based on PDEs, fluid equations of state and the plastic bag method of discretizing the PDEs with respect to time and space is proposed. This model shows high fidelity and accurate results in comparison to the Original Plastic Bag model due to its ability to properly and accurately describe the behavior of oil and gas based on wellknown correlations that define their properties. Operating points map is present to show the behavior of the oil and gas in the AGL systems. Comparison between the proposed model and the Original Plastic Bag model is shown.
