Investigating fluid flow through a choke valve*

Flow within a control valve is complex, particularly for choke types with multiple fluid entries. Despite their abundant use in industry, there is lack of fundamental fluid dynamics understanding of such valves. Failure through e.g. flow-induced vibration remains a common problem. Through academia-industry collaboration, fluid flow through an actual choke valve is investigated. Integrated Computational Fluid Dynamics (CFD) simulations and Particle Image Velocimetry (PIV) experiments have been used to study valve current under various flow rates and choking conditions. Close agreement is found between the two methods. Velocity, vorticity, pressure, temperature, and density contours are presented across different three-dimensional planes inside the valve. At low valve opening with few contributing flow streams, the analysis points to the formation of a specific, consistent structure established upon head-on collision of the incoming jets within the valve, becoming more complex at higher valve openings where multiple flow streams are engaged. Signal processing in the form of Fast Fourier Transform (FFT), autocorrelation, and continuous wavelet transform is conducted to identify dominant modes of vortex shedding frequency leading to potentially destructive vibration.