[PDF] Modeling Of Vibratory Cavitation Erosion Test Results By A Weibull Distribution eBook
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The rate of mass loss in vibratory cavitation erosion tests varies with time. As a consequence, this process is treated empirically. It is suggested by the author that the cumulative mass loss-time curve test results can be represented accurately by the Weibull cumulative distribution function. This model was verified for 26 tests of nine metals. Among these metals is Ni 200, which is a standard reference material for erosion tests. This model allows treating the results of vibratory cavitation erosion tests analytically, thereby obtaining invaluable information from the test data.
The improved method for determination of cavitation erosion resistance is based on the erosion strength concept and the Weibull cumulative distribution function. Cavitation erosion resistance is the ratio between the erosion intensity, which is the external load, and the erosion rate, which is the response of the eroded material. The time at which this erosion rate is determined is t200, i.e., when the average eroded thickness reaches 200 μm. This time ensures that the cavitation erosion resistance of both the boundary layer and the base material can be determined. The improved method is simple, easy to apply, and overcomes the drawbacks of the normalized erosion method and the erosion strength method. In this case, cavitation erosion resistance is an independent, measurable value with units of stress.
In the report, six scaling laws are derived and used to investigate the feasibility of modeling cavitation erosion. The velocity scale and size scale are studied with regard to six nondimensional ratios, namely. the erosion number, the relative nuclei size, the Weber number, the cavitation number, the cavitation inception number and the degree of cavitation. These scaling laws indicate that it is possible to model erosion in the laboratory and to predict the prototype performance. In addition, these scaling laws may be used to explain many currently available experimental observations.
Corrosion and Corrosion Protection of Wind Power Structures in Marine Environments: Volume 1: Introduction and Corrosive Loads offers the first comprehensive review on corrosion and corrosion protection of offshore wind power structures. The book provides extensive discussion on corrosion phenomena and types in different marine corrosion zones, including the modeling of corrosion processes and interactions between corrosion and structural stability. The book addresses important design issues, namely materials selection relative to performance in marine environments, corrosion allowance, and constructive design. Active and passive corrosion protection measures are emphasized, with special sections on cathodic corrosion protection and the use of protective coatings. Seawater related issues associated with cathodic protection, such as calcareous deposit formation, hydrogen formation and fouling, are discussed. With respect to protective coatings, the book considers for the first time complete loading scenarios, including corrosive loads, mechanical loads, and special loads, and covers a wide range of coating materials. Problems associated with fouling and bacterial-induced corrosion are extensively reviewed. The book closes with a chapter on recent developments in maintenance strategies, inspection techniques, and repair technologies. The book is of special interest to materials scientists, materials developers, corrosion engineers, maintenance engineers, civil engineers, steel work designers, mechanical engineers, marine engineers. Offshore wind power is an emerging renewable technology and a key factor for a cleaner environment. Offshore wind power structures are situated in a demanding and challenging marine environment. The structures are loaded in a complex way, including mechanical loads and corrosive loads. Corrosion is one of the major limiting factors to the reliability and performance of the technology. Maintenance and repair of corrosion protection systems are particularly laborious and costly. Explores the literature between 1950 and 2020 and contains over 2000 references Offers the most complete monograph on the issue Covers all aspects of corrosion protection in detail, including coatings, cathodic protection, corrosion allowance, and constructive design, as well as maintenance and repair Delivers the most complete review on corrosion of metals in marine/offshore environments Focuses on all aspects of offshore wind power structures, including foundations, towers, internal sections, connection flanges, and transformation platforms
In the framework of the International Cavitation Erosion Test (ICET), 119 vibratory cavitation erosion tests were performed. Seventy of these tests were with vibrating specimens (VRV), and forty-nine with stationary specimens (VRS). From these tests, twenty tests of each type were chosen for this study. VRV tests are covered by ASTM G32-10, whereas for VRS, no standard has yet been published. This anomaly stems from the difficulties encountered in both testing and evaluating of VRS tests. All forty cavitation erosion-time curves were analyzed by the Transient Response for Erosion (TRE) method. For each curve, all three parameters were determined, namely: time lag (TL), time constant (?), and the asymptotic value of the mean depth of erosion, mean depth of erosion (MDE) MDEMAX. These parameters were further applied to calculate the scatter of test results as obtained from various specimens tested under identical conditions. This method enables the determination of the absolute and relative scatter values at any time value along the test. Finally, several guidelines are specified for preparation of a future VRS standard.