Thermal behavior of marine lip seals: A pathway towards condition monitoring
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Insinööritieteiden korkeakoulu |
Master's thesis
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Language
en
Pages
77 + 11
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Abstract
Marine lip seals are commonly used in a variety of marine propulsion systems. Predicting marine lip seal behavior, however, is difficult: the harsh conditions in which the seals operate increase the likelihood of malfunction, wear, and failure. Moreover, published literature pertaining to the matter is exceedingly scarce. Condition monitoring addresses the main shortcomings associated with the use of marine lip seals, such as operational oil spillage and costly unscheduled maintenance. This thesis examines the behavior of marine thruster lip seals in a full-scale, fully flooded environment with a view to developing a condition monitoring system. Lip contact temperature was identified as a suitable variable to characterize the condition of the seal. A custom measurement device was built to measure the sub-surface contact temperature of multiple seals in a commercial thruster seal package operating fully submerged. In addition, a literature survey was performed, whereby the most widely accepted theories and experimental results pertaining to the fundamental mechanisms of lip seal function, the influence of thermal effects on lip seal operation, lip seal behavior in marine applications, and the condition monitoring of lip seals were reviewed and summarized. The studied seal package consisted of three similar seals, each having a 300 mm nominal diameter. A tungsten carbide coated stainless steel shaft liner was used as the counter-face. The liner was drilled to accommodate thermocouples situated 0.5 mm beneath the contact, thus facilitating the sub-surface measurement of lip seal contact temperature. Sub-surface contact temperature was measured at five points across each seal. Seals were tested under conditions that simulated normal running, and conditions that precipitated seal failure. Shaft rotational speed was varied during the tests. Water and lubricating oil temperatures, as well as shaft rotational speed, were measured. Pressure differentials across each seal were also measured. Experimental results were found to be in agreement with the literature. The results from this thesis validated the viability of the proposed concept as a suitable basis for a condition monitoring system for marine thrusters. In addition, they highlighted the interdependent nature of seal thermal behavior in a package configuration.Description
Supervisor
Viitala, RaineThesis advisor
Saikko, VesaMorad, Omar