THE INFLUENCE OF THERMAL PERFORMANCE OF TWT CATHODE-HEATER ASSEMBLY BY DIFFERENT CONTACT FORM BETWEEN INNER HEAT SHIELD AND SUPPORT CYLINDER

In this paper,the influence of thermal performance of cathode-heater assembly of Traveling Wave Tube(TWT),which has different contact form between inner heat shield and supporting cylinder,is analyzed using the simulation software ANSYS.With both thermal radiation and heat conduction are considered,the temperature and heat flux distribution of structures with different contact form are calculated,and also starting time which is needed before temperature come into steady status.The result of analysis suggests that changing the contact form between inner heat shield and support cylinder can influence the thermal performance of cathode-heater assembly and improve assembly's temperature distribution and promote heater's heating efficiency.The result of this paper provides theoretical guidance in the design of cathode-heater assembly.

某水平井钻杆管体断裂失效机理分析

某水平井在倒划眼起钻过程中频繁发生憋钻现象,解卡过程中位于下部水平段的一钻杆本体处断裂。对断裂钻杆进行了力学性能、显微组织及有限元受力模拟等分析。结果表明,该钻杆在通过硬质岩层时,外壁与井壁发生了严重的摩擦磨损现象,使得钻杆外壁温度急剧升高,加之钻井液的冷却作用,外壁表层发生了二次马氏体相变,产生了硬化层,在井下复合载荷的作用下,在钻杆加厚过渡带应力集中区域的硬化层萌生早期疲劳热裂纹,并最终穿透整个钻杆壁厚导致断裂失效。通过此次疲劳热裂纹失效机理分析,提出了对钻杆外壁采用防磨装置,降低钻杆表面由于摩擦磨损作用产生的热能等改善措施。