Experimental Research With PIV On The Flow Field In Valve Play Of Drilling Pump Valve

The failure of the drilling pump is always due to the break of the drilling pump valve which is one of the most important but also the weakest parts of the drilling pump, seriously affecting the normal operation of petroleum production. Over the decades, the degradation of drilling pump valves has been investigated extensively and various failure mechanisms have been proposed. However, no experimental test on the fluid has been successfully performed to support some of these mechanisms. In this thesis, tests on the flow within the valve play are carried out to investigate the factors resulting in the failure of the valve. With the designed experimental apparatus, the particle image velocimetry technology (PIV) is employed to perform the experimental research on the flow characteristics of the valve play. During the testing, particle images of the valve play are captured separately under 9 working conditions of different valve angles and different valve lifts, and states of the flow field are derived after image processing. With the results, the general features of the flow are analyzed and summarized from the perspectives of velocity profiles, vorticity distributions and trend charts of velocity. A PIV test with fluorescent particles is also conducted, presenting a clear parabolic layered profile of velocity and a distribution of the velocity fluctuation. The PIV results shows good agreement with previous numerical simulations of the flow. The measuring accuracy of PIV tests is discussed from aspects of precision of PIV system, following behavior of tracing particles and light refraction. Based on the variation of maximal velocity, a mathematical model of velocity in the valve play is established in the last part of the thesis, and according to the flow features and theories of material wear, the thesis gives a comprehensive evaluation of valve failure caused by erosion and abrasion in a practical valve working with drilling slurries and makes suggestions on the improvement of the pump valve.