基于功率管理的动力定位系统推力分配方法研究

以全电力推进船舶为研究对象,针对船上其他用电设备的功耗波动对电力系统的影响这一实际情况,在不影响定位功能的前提下,在原有的推力分配基础上研究具有功率管理功能的推力分配策略,采用基于动态负载控制法的推力分配方法,以达到减小电网总功耗波动和提高船舶电力系统稳定性的目标.仿真验证此方法导致的船舶在速度和位置上的偏差被成功地限制在一定范围内,也证明了如此小的偏差足以实现减小电网功耗波动的目标.     

测井仪器在流体中所受推力的测量方法研究

由于测井仪器在被泵送的过程中,其所受流体的推力难以直接进行测量,因此,本文提出了一种间接的测量方法,即利用密封液体内部压强处处相等的原理,采用盲孔将指定端面处的压力引出到便于观察的仪器尾部,用压力传感器实现动态压力测量.文中通过试验与数值模拟2种手段对该方法进行验证,并在此基础上进行工业应用试验.结果表明,该方法测量结果准确,操作简单方便,节约成本,能够满足工程应用的要求.     

CFD simulation of propeller and rudder performance when using additional thrust fins

To analyse a possible way to improve the propulsion performance of ships,the unstructured grid and the Reynolds Average Navier-Stokes equations were used to calculate the performance of a propeller and rudder fitted with additional thrust fins in the viscous flow field.The computational fluid dynamics software FLUENT was used to simulate the thrust and torque coefficient as a function of the advance coefficient of propeller and the thrust efficiency of additional thrust fins. The pressure and velocity flow behind the propeller was calculated. The geometrical nodes of the propeller were constituted by FORTRAN program and the NUMBS method was used to create a configuration of the propeller,which was then used by GAMMBIT to generate the calculation model. The thrust efficiency of fins was calculated as a function of the number of additional fins and the attack angles. The results of the calculations agree fairly well with experimental data,which shows that the viscous flow solution we present is useful in simulating the performance of propellers and rudders with additional fins.     

环境压强对水下两相冲压式发动机推力影响的数值模拟研究

文章应用CFD商业软件FLUENT6.3模拟了水下两相冲压式发动机的内流场以及分析了环境压强对发动机内推力的影响.假设流动为稳定流动,空气是不可压缩的并且空气和水之间没有热量交换.在航行速度,环境压强和喷气角度不变的条件下,发动机内推力随着空气的质量流量增大而增大;内推力的动态分量随空气的质量流量增大而增大,静态分量几乎保持不变.在航行速度,通气量和喷气角度不变的条件下,发动机内推力随着环境压强增大而增大;内推力的静态分量随环境压强增大而增大,动态分量几乎保持不变.     

隧道管环端面平整偏差自动评估技术研究

为解决当前手段不能实现管环端面平整偏差自动测量的问题，及时为人工补偿平整偏差提供数据依据，基于所建立的模型设计自动测量方案并对测试应用结果进行分析总结。通过分析盾构施工特点，确定可在盾构坐标系内表征测量点坐标，在此基础上推导基于推进油缸行程的管环平整偏差数学模型，证明基点与测量点间距与安装角度关系可由三角函数描述，且可在平面直角坐标系内计算平整偏差。设计基于油缸行程传感器的评估算法、测量方案，实际测试的数据表明，和人工测量结果相比，该系统能以较高精度自动监测管环平整偏差，有效降低测量人员的劳动强度。     

曲轴纵振对连杆大头止推轴肩磨损的影响

针对某内燃机曲轴与连杆大头止推轴肩磨损问题,采用Excite-PU建立机体-曲轴系统动力学模型,对曲轴纵向振动进行仿真研究。在此基础上,进一步研究曲轴纵振对曲柄销位移及曲拐开档尺寸的影响,据此构建磨损比率模型,用以判断曲轴易磨损位置。结果表明,曲轴纵振可导致曲轴与连杆大头止推轴肩间隙减小,进而发生磨损,且理论分析的易磨损位置也与实际磨损位置对应。     

盾构施工参数对土体及单桩的影响

采用对隧道洞室周边及开挖面的土体施加由盾构机引起的各种荷载的方法模拟盾构施工,通过变化注浆压力及推进力研究盾构施工对周边土体及单桩基础的影响.增加注浆压力是减小盾构推进对周围土体影响的最有效的措施.当注浆压力足够大,推进力、盾尾脱离及浆液硬化对土体的影响程度相同.若使隧道顶点的沉降及隧道底部土体的回弹减小相同的数量,底部注浆孔的压力要大于顶部注浆孔的压力.当推进力大于临界值时,推进力对隧道周边土体的影响明显增加.隧道周边及地表处各点的位移变化主要发生在盾构机通过这些点所在位置时,衬砌生成后,随后的开挖步对其影响很小.桩侧隧道洞室衬砌生成后,随后开挖步施加的注浆压力可以明显减小桩顶沉降,注浆压力越大,桩顶最终沉降越小.推进力对桩顶沉降影响不明显.盾构施工引起的桩顶和桩底的沉降始终相同,即桩整体下沉.桩顶无荷载及桩顶施加工作荷载时,开挖引起的桩顶沉降相同;桩顶施加极限荷载时,开挖引起的桩顶沉降明显增加.     

Evaluation of ultimate strength of stiffened panels under longitudinal thrust

A series of collapse analyses is performed applying nonlinear FEM on stiffened panels subjected to longitudinal thrust. MSC.Marc is used. Numbers, types and sizes of stiffeners are varied and so slenderness ratio as well as aspect ratio of local panels partitioned by stiffeners keeping the spacing between adjacent longitudinal stiffeners the same. Initial deflection of a thin-horse mode is imposed on local panels and that of flexural buckling and tripping modes on stiffeners to represent actual initial deflection in stiffened panels in ship structures. On the basis of the calculated results, buckling/plastic collapse behaviour of stiffened panels under longitudinal thrust is investigated. The calculated ultimate strength are compared with those obtained by applying several existing methods such as CSR for bulk carriers and PULS. Simple formulas for stiffened panels, of which collapse is dominated fundamentally by the collapse of local panels between longitudinal stiffeners, are also examined if they accurately estimate the ultimate strength. Through comparison of the estimated results with the FEM results, it has been concluded that PULS and modified FYH formulas fundamentally give good estimation of the ultimate strength of stiffened panels under longitudinal thrust.     

扰流片式推力矢量控制的气动力学研究

文章基于气动力学中激波的相关原理,通过数值模拟研究了扰流片式推力矢量控制的工作原理、燃气流动偏转以及燃气与扰流片之间的相互作用。以减小扰流片侧向引起的推力损失为目的,基于膨胀波及超声速普朗特-迈耶流动的基本原理,获得了减小扰流片对燃气核心射流影响的基本方法,并通过数值模拟验证了R-73扰流片式推力矢量控制气动设计的合理性,获得了其扰流片、致偏装置的基本设计原则。     

重型工程车推力杆的设计匹配

以某重型工程车为基础,通过建立平衡悬挂受力分析模型,计算出推力杆在各极限工况下受力值的大小。结合常见推力杆实际使用故障,通过CAE辅助分析手段对推力杆结构进行了优化设计,并对优化后的结构进行了扭转、拉伸、弯曲和疲劳试验。试验结果表明,优化设计后的推力杆完全满足重型工程车在恶劣工况下的使用要求。