[FKFU-B060-00-A] Validation2 : Developments in unsteady pipe flow friction modelling

게시자: Songyi Han, 2017. 12. 5. 오후 6:17
Introduction

This paper compares FloMASTER simulation results with those presented in “Developments in unsteady pipe flow friction modelling” [4] and demonstrates the accuracy of the software. The aforementioned source paper presents pressure traces measured in a water pipeline after rapid valve closure at three velocities. This paper will compare the pressure traces from the source paper with results from FloMASTER at these three velocities. Both FloMASTER Quasi-steady and Unsteady Friction models have been used.



Statement of Problem


The experimental set-up is shown in Figure 15. Water flows upward from Tank 2 to Tank 1and is throttled at the valve to the required fluid velocity. Once a steady state system has been achieved the valve is quickly closed. The induced pressure wave is then recorded by the five pressure sensors along the pipeline. Table 10 includes further details about the system.




FloMASTER Solution
The FloMASTER network used to replicate the above scenario is presented below in Figure 16.






Note that Component 1: Constant Head Reservoir, (The outflow reservoir), ‘Liquid Level above Base’ has been determined through matching between results and is not specified from source paper [4].



Fluid Velocity 0.1 m/s


The resulting pressure traces are obtained from the FloMASTER network from viewing the ‘Pressure’ at Hydraulic Node 3, for results at the Ball Valve, and the ‘Internal Pressure’ halfway along the pipe for Component 4; Pipe: Cylindrical Elastic.



Figure 17 presents the pressure traces for a system steady state velocity of 0.1 m/s. It can be seen that the FloMASTER Unsteady Friction model has a good matching with the experimental results. The Quasi-Steady Friction model matches the initial pressure wave produced from the valve closure, however as the pressure wave deteriorates the discrepancies between the results increase due to the model not being designed for fast transients such as this case. Similar agreements are demonstrated in Figures 18 and 19.


Fluid Velocity 0.2 m/s





Fluid Velocity 0.3 m/s





Conclusions

Using FloMASTER, the experimental results were recreated well using the Unsteady Friction model. The Quasi-Steady Friction model was able to capture the initial pressure surge however the model effectiveness decreased as the pressure wave began to dissipate.
Ċ
Songyi Han,
2017. 12. 5. 오후 6:17
Comments