离心泵蜗壳内压力脉动特性数值分析

为揭示离心泵蜗壳流道内的压力脉动变化规律,采用雷诺时均方法(RANS),对3种工况下的离心泵内部三维非定常湍流流场进行数值计算,分析同一蜗壳断面不同位置以及沿蜗壳周向不同点的压力脉动特性。结果表明:蜗壳流道内具有非常明显的压力脉动,在各种工况下压力脉动的主频均是叶片通过频率;同一蜗壳断面上的压力脉动从蜗壳底部到蜗壳背面先减小后增大,蜗壳底部监测点的高频脉动成分较多;沿蜗壳周向,随着圆周角的增大,压力脉动减弱,隔舌附近压力脉动幅度最大,且高频脉动成分明显增加。     

探索打造特色协会 推动内部审计双转型

近三年来,武汉市内部审计师协会（以下简称协会）依靠省内审协会、市审计机关和会员单位,按照《审计署关于内部审计工作规定》和《中国内部审计准则》要求,围绕服务武汉经济社会改革发展总目标和会员单位的需求．以推动协会工作转型、内审业务转型为主线．     

新形势下企业审计的转型

当前武汉正处在“十二五”计划实施之年。复兴“大武汉”的冲锋号已经吹响。审计机关如何更好地服务于市委、市政府提出的“工业强市”战略目标，为实现我市“工业倍增”计划做出贡献，审计人员应该认真思考企业审计如何更好地适应新形势的客观要求，加快审计思路转变，创新企业审计方法，不断深化企业审计工作，使其更好地服务于经济跨越式发展。     

从服务国家治理角度谈企业审计信息化

本文从新时期企业审计所面临的新形势、新任务入手,指出现阶段企业审计要发挥国家治理的作用,就必须紧密关注信息化条件下企业生产经营和内控管理状况,加快推进企业审计信息化,全面掌握信息化条件下企业审计的方法和手段,加大数据分析应用力度,逐步探索开展企业信息系统审计。同时要加强"人、法、技"建设,为企业审计信息化提供人才、技术和法律保障。     

新形势下企业审计的转型

当前武汉正处在十二五计划实施之年,复兴大武汉的冲锋号已经吹响。审计机关如何更好地服务于市委、市政府提出的工业强市战略目标,为实现我市工业倍增计划做出贡献,审计人员应该认真思考企业审计如何更好地适应新形势的客观要求,加快审计思路转变,创新企业审计方法,不断深化企业审计工作,使其更好地服务于经济跨越式发展。     

Experimental investigation and numerical analysis of unsteady attached sheet- cavitating flows in a centrifugal pump

This paper studies the attached sheet cavitation in centrifugal pumps. A pump casted from Perspex is used as the test subject. The cavitation bubbles were observed in the entrance of the impeller and the drops of the head coefficients were measured under different operating conditions. A Filter-Based Model (FBM), derived from the RNG k – ? model, and a modified Zwart model are adopted in the numerical predictions of the unsteady cavitating flows in the pump. The simulations are carried out and the results are compared with experimental results for 3 different flow coefficients, from 0.077 to 0.114. Under four operating conditions, qualitative comparisons are made between experimental and numerical cavitation patterns, as visualized by a high-speed camera and described as isosurfaces of the vapour volume fraction α_v = 0.1. It is shown that the simulation can truly represent the development of the attached sheet cavitation in the impeller. At the same time, the curves for the drops of the head coefficients obtained from experiments and calculations are also quantitatively compared, which shows that the decline of the head coefficients at every flow coefficient is correctly captured, and the prediction accuracy is high. In addition, the detailed analysis is made on the vapour volume fraction contours on the plane of span is 0.5 and the loading distributions around the blade section at the midspan. It is shown that the FBM model and the modified Zwart model are effective for the numerical simulation of the cavitating flow in centrifugal pumps. The analysis results can also be used as the basis for the further research of the attached sheet cavitation and the improvement of centrifugal pumps.     

澳大利亚内部审计的经验和启示

最近，笔者随武汉市内部审计监督培训团赴澳大利亚进行了为期22天的内部审计专业培训和访问。在澳培训、访问期间，学习了澳大利亚内审理论、内审工作程序、内审技术和方法，了解了澳内审协会工作情况、政府部门内部审计工作开展以及内审机构开展风险评估和绩效审计的情况等。我们感到这次培训收获很大，开阔了视野，更新了观念，了解了先进的内部审计技术和方法，对今后进一步拓展内审工作思路，