Papers by Keyword: Cavitation

Abstract: Cavitation is a critical issue in centrifugal pumps, leading to severe mechanical wear, reduced efficiency, and potential system failure. This study investigates cavitation in a centrifugal pump operating in a Hydrocracking Complex (HCC) using vibration analysis combined with Fast Fourier Transform (FFT) spectral diagnostics. The results reveal characteristic cavitation signatures, including Blade Pass Frequency (BPF) peaks, 1X RPM harmonics, and high-frequency random vibrations exceeding 120k CPM, with overall amplitudes ranging from 5.53 to 9.17 mm/s. Despite component replacement, vibration levels remained elevated, indicating that persistent low-flow conditions, suction-side pressure fluctuations, and deviation from the Best Efficiency Point (BEP) were the root causes of cavitation. The findings demonstrate that vibration spectrum analysis provides a quantitative and reliable tool for diagnosing cavitation severity under real industrial conditions. Unlike many laboratory-based studies, this work contributes an industrial case study from a hydrocracking unit, offering practical insights into predictive maintenance strategies for large-scale pumping systems.

Abstract: In many different industries, cavitation-induced erosion and damage to engineering parts have been a major problem. This is especially true when it comes to fluid systems. Modern materials and welding methods are always being researched to improve the components' resistance to cavitation damage as a way to address this problem. This study examines the cavitation resistance of friction stir welded joints made of high-purity copper alloy Cu99, which has promising mechanical qualities. The project entails the creation of friction stir welded joints made of Cu99 copper, followed by extensive testing to see how well they resist erosion caused by cavitation. A cavitation testing device is used for the testing, simulating the circumstances that can cause cavitation damage to fluid systems in the actual world. The cavitation intensity, exposure time, and temperature changes are the relevant parameters. The performance and longevity of the friction stir welded joints under cavitation conditions are assessed using the experimental results. Investigations are conducted into the effect of post-weld heat treatment, grain boundary features, and microstructural changes in improving cavitation resistance. The goal of the study is to offer important new information on friction stir welding's potential as a method for raising the cavitation resistance of Cu99 copper components.

Abstract: Aluminium alloys are being used more often as a result of industry demands for strong, lightweight materials. Because of its advantages over conventional fusion welding techniques, friction stir welding, or FSW, has become a promising technique for joining aluminium alloys. Nonetheless, there is still cause for concern regarding FSW joints' vulnerability to cavitation erosion, which is a major issue in applications exposed to harsh environments. The cavitation resistance of EN AW 1200 aluminium alloy joints made by the FSW process is the main objective of this study. By utilizing specialized equipment to conduct cavitation tests, the study uses a comprehensive methodology to assess the cavitation erosion behaviour of these joints. A number of variables are investigated in order to determine how they affect the cavitation resistance of the welded joints, including mechanical attributes, welding parameters, and microstructural features. The goal of the study is to shed light on how well FSW joints function and hold up in cavitation scenarios. This information will be useful in improving the dependability and suitability of EN AW 1200 aluminium alloy in sectors where the ability to withstand cavitation erosion is critical. The findings from this study are expected to contribute to the optimization of welding parameters and material selection, ultimately advancing the use of aluminium alloys in critical applications requiring resistance to cavitation-induced damage.

Abstract: This article presents the results of experimental processing of hydrocarbons (petroleum and mixtures based on them) on a laboratory stand. Cavitation treatment was carried out in flow-type rotary-pulsation apparatus with different impeller diameters and rotor rotation frequencies. The aim of the work was to determine the most effective processing mode for oil blends and distillates within the framework of laboratory experiments.

Abstract: Cleaning tests with ultrasound-superposed water jets are performed to explore the optimal injection distance from the jet nozzle to a glass plate spin-coated with small silica particles (as a cleaning sample). The cleaning performance is evaluated based on particle removal efficiency (PRE) that is calculated using the haze method. Visualization of the water jet and liquid film flow over the cleaning target shows that the jet flow with short injection distance tends to be in a steady state, while the water jet shape instability grows for long injection distance, leading to atomization of the jet. The cleaning tests with varying the injection distance suggest that there exists an optimal injection distance at which the PRE becomes maximal.

Abstract: During cavitation investigations with manganese-aluminum-bronzes (MAB) in seawater using ultrasound (US), it was found that the microstructure of the bronze was developed by etching. To investigate this phenomenon in more detail, metallographically polished MAB samples were US-treated in synthetic seawater. On the one hand, pulsed ultrasound was used with a sonotrode in order to be able to observe the effects of cavitation. On the other hand, an ultrasonic bath with less power than the sonotrode was used to investigate the influence of ultrasound on the electrochemical response of the MAB. It was found that the k-phase is attacked most severely by cavitation, followed by β-phase and the α-phase. Potentiostatic measurements indicated that the transport of oxygen to, and of metal ions from the metal surface is enhanced by the ultrasound, which then leads to increased corrosion rates.

Abstract: The authors investigated the effect of ultrasonic cavitation on the surface of St3, 20, 45 steels. It was found that cavitation causes a change in the structure and properties of the surface layer of the samples. A refinement of the grain and an increase in the microhardness of the surface layer similar for the investigated materials were revealed. The dependences of dynamics of the increase in microhardness under the action of ultrasound were given, which show that there was a steady state, characterized by an indicator of relative microhardness of 1.3...1.5. The results of changes in the parameters of roughness and sub-roughness were given. Studies showed that cavitation erosion leads to an increase in altitude and step parameters of the surface microgeometry. The research results can be used for development and creation of ultrasonic technological processes carried out in liquid media.

Abstract: The current view on the determination of the abrasion resistance of a cement composite is mainly focused on the resistance of the composite to the effects of mechanical abrasion. However, many concrete structures are exposed to the abrasive effects of flowing liquids. One of the test procedures simulating this principle of abrasion is based on the creation of a very fast flow of liquids, often including abrasive media. Based on worldwide published research on the given topic, the use of the action of ultrasonic waves in a liquid, leading to the simulation of the cavitation stress of a composite, which is a very dangerous phenomenon, is considered a suitable method for creating the mentioned abrasion effects. The following article discusses new possibilities for simulating and evaluating the abrasive effects of cavitation on cement composites using the action of ultrasonic waves in a liquid. These effects will be monitored on cement pastes, which will be modified with several types of commonly used admixtures. Furthermore, the connection between the effects of the mentioned abrasive action and several physical-mechanical parameters will be monitored.

Abstract: Unlike traditional materials, the development of high-performance foamed concrete with a compressive strength of up to 20 MPa and a density of up to 1400 kg/m³ allows the use of foamed concrete as a constructive material with additional functions including good thermal insulation properties, sound insulation and capillary porosity needed to ensure hydrothermal conditions. Unlike autoclaved aerated concrete, foamed concrete can also be used in monolithic construction.The studies of high strength foamed concrete were performed by using mostly local mineral components and mixing technology by using planetary activator which provides a fundamentally new mixing mode that combines intensive mixing, foaming and activation of components. To realize the experimental part of the research, turbulence type foamed concrete mixer SPBU-LUKS was used.

Abstract: Thus far, axial flow pumps remain a significant hydrodynamic unit. These pumps have common applications for various systems that require a high flow rate and a lower head. They tend to be less efficient and consume excessive power when operating at low flow conditions. Most of the studies focus on improving the hydraulic performance of these pumps based on the best efficiency point (BEP) flow conditions. This approach is mostly based on the assumption that the pump will always operate at BEP. However, this is not always the case, because the operational condition of the pump may require an adjustment to meet certain system demands. Hence, it is necessary to emphasize the need to improve the hydraulic performance of these pumps for multiple flow conditions. This means that in addition to BEP, the lowest, and the highest operational conditions need to be considered when improving the pump performance. Also, it is important to review the phenomenon of cavitation in every design optimization investigation, given its significance to pump performance and some misrepresentation which are sometimes associated with its assessment. Therefore. the main contribution of this article is to briefly discuss the successful and unsuccessful design optimization methods of an axial flow pump. Furthermore, it highlights the significance of improving the pump performance at multiple flow conditions and also to incorporate the analysis of using CFD methods to analyze the results of cavitation performance in every pump performance improvement investigation.