Jeffreys S, di Mare L, Liu X, Morgan N, Wong J S S
Department of Mechanical Engineering, Imperial College London SW7 2AZ UK
Oxford Thermofluids Institute, Department of Engineering Science, St John's College, University of Oxford OX2 0ES UK.
RSC Adv. 2019 Jan 11;9(3):1441-1450. doi: 10.1039/c8ra09396b. eCollection 2019 Jan 9.
Lubricants operating in elastohydrodynamic (EHD) contacts exhibit local variations in rheological properties when the contact pressure rises. Direct evidence of this behaviour has only been obtained by examining through-thickness velocity profiles () of lubricants in a contact using luminescence-based imaging velocimetry. In the present study, nanoparticles (NPs) are added to polybutene (PB) as tracers to investigate the effect of pressure on the flow of PB in an EHD contact. By tracking NPs in the contact, particle velocity distributions () under various pressures are obtained and found to be pressure dependent. Results show quantitatively that () and () are correlated and thus confirm that () of PB changes from Couette flow to partial plug flow above a critical pressure. This confirmation highlights the complexity of lubricant rheology in a high pressure contact.
在弹性流体动力（EHD）接触中运行的润滑剂，当接触压力升高时，其流变特性会出现局部变化。这种行为的直接证据仅通过使用基于发光的成像测速技术检查接触中润滑剂的全厚度速度分布（）获得。在本研究中，将纳米颗粒（NPs）作为示踪剂添加到聚丁烯（PB）中，以研究压力对EHD接触中PB流动的影响。通过跟踪接触中的NPs，获得了不同压力下的颗粒速度分布（），发现其与压力有关。结果定量地表明（）和（）是相关的，从而证实PB的（）在临界压力以上从库埃特流转变为部分柱塞流。这一证实突出了高压接触中润滑剂流变学的复杂性。
