a b s t r a c tIn view of the limitations of the existing Newton fluid effects on the vortex flow mechanism study, numerical analysis of non Newton fluid effects was presented. Using Reynolds stress turbulence model (RSM) and mixed multiphase flow model (Mixture) of FLUENT (fluid calculation software) and combined with the constitutive equation of apparent viscosity of non-Newtonian fluid, the typical non-Newtonian fluid (drilling fluid, polymer flooding sewage and crude oil as medium) and Newton flow field (water as medium) were compared by quantitative analysis. Based on the research results of water, the effects of non-Newtonian rheology on the key parameters including the combined vortex motion index n and tangential velocity were analyzed. The study shows that: non-Newtonian rheology has a great effect on tangential velocity and n value, and tangential velocity decreases with non-Newtonian increasing. The three kinds of n values (constant segment) are: 0.564(water), 0.769(polymer flooding sewage), 0.708(drilling fluid) and their variation amplitudes are larger than Newtonian fluid. The same time, non-Newtonian rheology will lead to the phenomenon of turbulent drag reduction in the vortex flow field. Compared with the existing formula calculation results shown, the calculation result of non-Newtonian rheology is most consistent with the simulation result, and the original theory has large deviations. The study provides reference for theory research of non-Newtonian cyclone separation flow field.
Due to some deficiencies in the existing researches of cutting element wear of polycrystalline diamond compact (PDC) drill bit and to reduce the wear rate of cutting element of PDC bit, accurately illustrate the effect of tooth-distributing angle on cutting element, and improve the service life of PDC drill bit, we use the geometry knowledge of PDC drill bit and establish the torsion vibration model of PDC drill bit, solve and analyze the model, and at last analyze the effect of tooth-distributing angle on the rule of cutting element wear by using the wear theory.
A self-propelled rotary cutting tool (SPRT) can be used in metal machining at higher cutting speeds with much longer tool life than conventional cutting tools because of the continuous rotation of its round tool insert driven by cutting force. The paper presents a theoretical calculation of cutting speed and feed rate for the SPRT together with practical concerns. Based on the research results and industrial experience the principles for choosing depth of cut in turning and face milling and general considerations concerning the application of the tools are detailed.
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