Non-axisymmetric diffuser pipe design to suppress the eccentric jet flow characteristic in a high-pressure angle valve

Angle valves are common flow control devices used in various industrial fields. However, under harsh conditions such as high pressure difference, severe eccentric jet flow phenomenon will occur in the diffuser pipe section, leading to significant erosion and wear on the valve walls. This ultimately results in a short service life for the valves and even safety hazards. Traditionally, some axisymmetric design methods are tried to be employed to suppress the eccentric jet flow. Even though they can play active roles, the control effect is usually limited. To better eliminate the eccentric jet flow characteristic, this paper has proposed a non-axisymmetric diffuser pipe design strategy in a high-pressure angle valve. The main purpose is to use a non-axisymmetric diffuser structure to control the non-uniform pressure distribution in the valve diffuser section. As is known, the asymmetrical structure of an angle valve leads to a non-uniform inflow at the diffuser inlet, resulting in distinct pressure recovery abilities on the two sidewalls and notable eccentric jet flow impacting a single sidewall. Results show that a non-axisymmetric diffuser pipe can improve the non-uniform pressure distribution and help suppress the eccentric jet flow. Specifically, a 2.5° diffuser pipe inclination design has the greatest effect on reducing the degree of eccentricity compared to the prototype valve. Moreover, the pressure recovery rate on the left sidewall becomes higher than that on the right sidewall, and a more uniform pressure distribution across the pipe can be obtained. In the meanwhile, the separation regions on both sidewalls of the diffuser present a similar size. A more uniform distribution of turbulence intensity is also noted near both sidewalls. As a consequence, the eccentric jet flow has been well suppressed in the first diffuser section, which is beneficial for reducing the erosion and wear on the single sidewall and improving the valve service life. In addition, cavitation is produced and developed in the throttle region and collapses in the diffuser pipe. As the turbulent kinetic energy is high in the cavitation zone, it is closely related to cavitation production and collapse. The non-axisymmetric diffuser design has decreased the volume of the cavitation zone on the right sidewall and reduced the hazard of cavitation wear in the local region. The research work might provide useful guidelines for designing reliable and long service-life high-pressure angle valves.