A simple method for high-precision evaluation of valve flow coefficient by computational fluid dynamics simulation

Abstract

Flow coefficient is an important performance index associated with the energy efficiency of a valve, and an effective method to evaluate valve flow coefficient is necessary for valve industry. However, theoretical estimation often results in poor accuracy, while experimental measurements involve significant costs in time and equipment. In this article, a computational fluid dynamics method is proposed to achieve simple and accurate evaluation of valve flow coefficient. For each valve, a computational fluid dynamics model is established containing a valve section, an upstream section, and a downstream section. A grid-adaptation strategy is then applied to improve the accuracy of simulation. To calculate flow coefficient, the most important issue is to determine the net pressure loss induced by valve (Δ P v ). Herein, the overall pressure drop (Δ P o ) is obtained first, and the pipe-induced pressure drop (Δ P p ) is estimated by linear fitting. Then, Δ P v is calculated as the difference between Δ P o and Δ P p . To ensure accurate estimation of the pressure losses, a length of 26 times of pipe diameter is preferred for the upstream section. The experiments demonstrated that the presented method can accurately predict flow coefficient for various types of valves and thus has great potential to be widely used in the valve industry.