Coupling Quasi-Two-Dimensional Friction Model and Discrete Vapor Cavity Model for Simulation of Transient Cavitating Flows in Pipeline Systems

Qiang Sun,Liang Chen,Ying Xu,Tae Uk Jang,Yuebin Wu

doi:10.1155/2020/8089308

Abstract

Accurate simulation of cavitating flows in pipeline systems is important for cost-effective surge protection. However, this is still a challenge due to the complex nature of the problem. This paper presents a numerical model that combines the discrete vapor cavity model (DVCM) with the quasi-two-dimensional (quasi-2D) friction model to simulate transient cavitating flows in pipeline systems. The proposed model is solved by the method of characteristics (MOC), and the performance is investigated through a numerical case study formulated based on a laboratory pipeline reported in the literature. The results obtained by the proposed model are compared with those calculated by the classic one-dimensional (1D) friction model with the DVCM and the corresponding experimental results provided by the literature, respectively. The comparison shows that the pressure peak, waveform, and phase of pressure pulsations predicted by the proposed model are closer to the experimental results than those obtained by the classic 1D model. This demonstrates that the proposed model that combines the quasi-2D friction model with the DVCM has provided a solution to more accurately simulate transient cavitating flows in pipeline systems.

Highlights

Significant hydraulic transients caused by pump trips or rapid valve closure in a pipeline system can induce pipe failure [1, 2]. ese damaging transient events typically involve very high positive pressure and very low negative pressure
In order to validate the accuracy of the proposed model, the numerical results computed by both the classic 1D model and the proposed quasi-2D model are compared with experimental results obtained by Bergant and Simpson [4]. e experimental system was a typical reservoir-pipe-valve system, which was composed of a copper straight and sloping pipe. e transient flows were caused by a rapid downstream valve closure. e wave speed was 1319 m/s
Experimental results on the pressure oscillation at the valve for the initial mean velocities of V0 0.30 m/s, 0.71 m/s, and 1.40 m/s are used in the current research. rough testing different grid sizes, the Nx value of 16 and the Nr value of 90 are used in the proposed model, which are capable of simulating transient cavitating pipe flows effectively and accurately

Summary

Introduction

Significant hydraulic transients caused by pump trips or rapid valve closure in a pipeline system can induce pipe failure [1, 2]. ese damaging transient events typically involve very high positive pressure and very low negative pressure.

Results

Conclusion