Investigation on hydrodynamic lubrication effect of micro groove seal in pharmaceutical kettle
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Abstract:
To improve the lubrication conditions of the seal in the pharmaceutical kettles, a specific shape groove with micrometer level on the sealing end face is set up to fully utilize the fluid dynamic pressure effect under given working conditions. A numerical model is developed to solve the pressure distribution in the micro groove, where any groove shape can be used. The numerical form of the model is derived using the principle of mass conservation without considering the film thickness derivative term, and the coordinate transformation is introduced to adapt to the curved shape of the groove. The cavitation phenomenon is taken into account in the flow field of the seal, and the JFO cavitation model is introduced to modify the Reynolds equation. The diversity of groove shapes is considered, and the node adsorption method is adopted to approximate the groove shape. The model is established based on the principle of mass conservation, which can adapt to any different groove shapes and has a strong scalability. By mathematical modeling and solving, the performances of the micro groove seal under different groove shapes are analyzed, providing a basis for the micro groove design of seal in pharmaceutical kettles.Keywords:
Groove (engineering)
Conservation of mass
본 연구는 타원형 노즐과 원형 노즐 내부에서 발생되는 cavitation의 발생 및 성장을 실험적으로 관찰하였다. 원형 노즐과 타원형 노즐의 cavitation 특성을 가시화 하기위해 투명한 아크릴로 노즐을 제작하였다. 실험에 사용된 노즐들은 같은 단면적으로 제작되었으며, 타원형 노즐의 경우 형상비(a/b)를 다르게 하였다. 분사압력의 증가에 따라 노즐내부 유동은 no cavitation, cavitation, hydraulic flip 영역으로 나뉘어졌다. 노즐의 형상에 상관없이 no cavitation과 cavitation 영역에서는 분사압력의 증가에 따라 유량은 증가하며, 유출계수는 감소하는 경향을 나타냈다. 그러나 hydraulic flip 영역에서의 유량계수는 일정한 값을 나타냈다. 타원형 노즐은 원형 노즐에 비해 높은 cavitation number에서 cavitation이 성장, 발달하였다. 특히 타원형 노즐에서는 장축의 cavitation length가 단축보다 길게 나타났다.
Discharge coefficient
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The present report describes about the effects of the amount of the alternate cutting back of the leading edges on the steady cavitation, its stability and the onset region of rotating cavitation. It was found that, by increasing the amount of cutting back, we can increase the range of cavitation number with stable cavitation and diminish the onset region of rotating cavitation.
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본 연구는 타원형 노즐과 원형 노즐 내부에서 발생되는 cavitation의 발생 및 성장을 실험적으로 관찰하였다. 원형 노즐과 타원형 노즐의 cavitation 특성을 가시화 하기위해 투명한 아크릴로 노즐을 제작하였다. 실험에 사용된 노즐들은 같은 단면적으로 제작되었으며, 타원형 노즐의 경우 형상비(a/b)를 다르게 하였다. 분사압력의 증가에 따라 노즐내부 유동은 no cavitation, cavitation, hydraulic flip 영역으로 나뉘어졌다. 노즐의 형상에 상관없이 no cavitation과 cavitation 영역에서는 분사압력의 증가에 따라 유량은 증가하며, 유출계수는 감소하는 경향을 나타냈다. 그러나 hydraulic flip 영역에서의 유량계수는 일정한 값을 나타냈다. 타원형 노즐은 원형 노즐에 비해 높은 cavitation number에서 cavitation이 성장, 발달하였다. 특히 타원형 노즐에서는 장축의 cavitation length가 단축보다 길게 나타났다.
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Surface texturing has been successfully applied to industry fields as a means for enhancing tribological properties of mechanical components.A computational fluid dynamics(CFD)model is developed to study the hydrodynamic capability of partially surface groove texturing on fully lubricated sliding.The effects of location parameter L,which is used to characterize a pattern of array on the friction pair surface,groove width D and Reynolds number Re on load bearing capacity of oil film are discussed in detail.The results show that location parameter Lhas a significant effect on load bearing capacity with low Reynolds number Re.When Lvaries from 0.4 to 0.05,e.g.,the load bearing capacity has an increase of 58.99% at Re=3 and D=0.2.However,an increase in Reynolds number Re may reduce this effect.Additionally,an optimal groove width Dfor the maximum load bearing capacity exists at a special depth of groove.
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