Under certain conditions, cavitation may occur within a pipe system. This can result in excessive wear of the pipe’s inner walls and valves which may compromis the structural integrity and function of the system. Computational fluid dynamics (CFD) software is a useful tool in determining if cavitation exists in systems with varying pressures and high fluid velocities. The scientific community has extensively studied the physical mechanics of cavitation; however, there is a shortage on experimental case studies where cavitation occurs in large industrial pipe networks.

In this study, a water conveyance system in chemical manufacturing facility is investigated. The pipe network is responsible for conveying approximately five million gallons of water per day (MGD) from a river adjacent to the facility to a storage basin located approximately 3,000 feet away. The exact age of the pipe system is unknown- limited construction or maintenance information exists. Of specific concern is an segment near the storage basin where three flow restrictions exist over a distance of approximately 30 feet.  These restrictions include two butterfly valves and an orifice plate on a 18-inch diameter steel pipe, buried approximately three feet bgs. Vibrations can be felt at the ground surface when standing in this area.

A computational model of the pipe network, based on limited engineering and operational data, was developed in the AFT Fathom software. The Fathom software was calibrated using flow and pressure data from the facility.  The model indicated that cavitation existed at the end of the system, where two butterfly valves and an orifice plate are used to control flowrate and reduce pressure from 80 PSI to 45PSI. While Fathom model cannot predict cavitiation, the kinematic parameters produced by the Fathom model indicate conditions that are similar to those during cavitation.

A reduced scale (4-inch diameter pipe) physical model of this segment of the pipe network was created to attempt to replicate this phenomenon and evaluate solutions. The physical model achieves geometric similitude with proportionate pipe diameters and pipe lengths and achieves kinematic similitude through use of a variable speed pump to model flow rate and velocity. A Fathom model of the reduced scale physical model was also created to assist in similitude evaluation. In this study, the control variables will be the pressure and fluid velocity between the two valves and orifice plate in the AFT Model; and the independent variables are the fluid velocity and pressure between the two valves and orifice plate in the physical model.

 


Vibration Analysis in Multiple Close Proximity Flow Restrictions

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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