Thesis
One-dimensional positive displacement pump description in cavitating conditions
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2019
- Thesis identifier
- T15488
- Person Identifier (Local)
- 201673023
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- The scope of the research contained in this thesis is to develop a new mathematicalalgorithm to model complex pump systems, capturing cavitationand pump behaviour. The approach consists of the solution of the hyperbolicwave equation, including compressibility and multiphase conditions.The second phase contains non-condensable gas and vapour formation, bothimportant in the density and speed of sound variation. The adopted solutionscheme is a finite volume method with a Monotonic Upwind Scheme forConservational Law (MUSCL). This algorithm is second-order accurate intime and space, with a total variation diminishing (TVD) scheme to preventspurious oscillation. In order to introduce a dissipation due to friction at thewall in a quasi-steady formulation, a source term is solved with a splittingmethod. To validate the code, the new simulation methodology was firstapplied to transient flow in a straight pipe with water hammer. The resultswere compared with results from pre-existing methodologies availablein the literature. Thereafter, the algorithm was applied to a single chamberpositive displacement diaphragm pump and then to a triplex diaphragmpump and the results compared with experimental data from an industrialtest rig for both single chamber pump and multiple triplex pump network.The simulations coped with a wide range of working pump conditions andwere capable of giving information on pressure pulsation, mass flow rateand volume fraction of the vapour formation inside the entire domain. Theresults modelled correctly the main pump behaviour especially for low cavitation formation, although cavitation was underestimated in same cases.Moreover, differences were evident out in the case of high pump rotationspeed where the vapour formation also affected the discharge phase. Forthat condition, the algorithm was not able to perform correctly, limiting theuse of the code. The algorithm may be easily extended to different positivedisplacement pump configurations, including a diaphragm pump where differentliquids are on the driven and driving sides of the diaphragm. Such ahydraulically driven diaphragm pump requires an intermediate flow whichtransfers the information from the piston to the membrane. This may beembedded in the algorithm. The capability of the new algorithm to copewith different design layouts to work as a pre-design tool has been highlightedas has its ability to simulate not only the pump behaviour but alsothe system network response to which the pump is attached. From an industrialpoint of view, a reduction in terms of simulation effort with high fidelity results permits a reduction in costs for the design process and animprovement in the knowledge of a pump's operating process. Moreover, itis possible to include the practical operation characteristic, often neglected,permitting a better estimate of the NPSHR by simulation.
- Advisor / supervisor
- Dempster, William
- Stickland, Matthew
- Resource Type
- Note
- Previously held under moratorium from 10 February 2020 until 10 March 2022
- DOI
- Date Created
- 2019
- Former identifier
- 9912812890702996
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