CFD理论黏性流场中三维振动水翼的非定常水动力性能(英文)

The motion of the fins and control surfaces of underwater vehicles in a fluid is an interesting and challenging research subject. Typically the effect of fin oscillations on the fluid flow around such a body is highly unsteady, generating vortices and requiring detailed analysis of fluid-structure interactions. An understanding of the complexities of such flows is of interest to engineers developing vehicles capable of high dynamic performance in their propulsion and maneuvering. In the present study, a CFD based RANS simulation of a 3-D fin body moving in a viscous fluid was developed. It investigated hydrodynamic performance by evaluating the hydrodynamic coefficients (lift, drag and moment) at two different oscillating frequencies. A parametric analysis of the factors that affect the hydrodynamic performance of the fin body was done, along with a comparison of results from experiments. The results of the simulation were found in close agreement with experimental results and this validated the simulation as an effective tool for evaluation of the unsteady hydrodynamic coefficients of 3-D fins. This work can be further be used for analysis of the stability and maneuverability of fin actuated underwater vehicles.     

两维翼水动力振动和流场显示的粒子图像测速实验

在小型循环水槽中进行两维翼水致振荡显示实验。流场显示以ＰＩＶ技术为主,辅以染料示踪技术。试验证明了ＰＩＶ技术可以应用于被动振动非定常复杂流场的测量中,并对两维翼流体旋涡诱发振动响应进行了分析。     

抗坏血酸对CH2（COOH）2-BrO3^--Mn^2＋-H2SO4体系化学振荡反应的影响

研究了抗坏血酸对CH2（COOH）2-BrO3^--Mn^2＋-H2SO4体系化学振荡反应的影响,考察了该体系中各反应物的初始浓度范围及主要影响因素．结果表明：在5．7×10^-4～8．5×10^-2mol／L的范围内,抗坏血酸对振荡反应的诱导期有较大影响,且抗坏血酸的浓度与振幅及抗坏血酸浓度的对数与诱导期倒数的对数均存在良好线形关系．诱导期和周期的表观活化参数分别为56．63kJ／mol,73．81kJ／mol;同时还对抗坏血酸参与下可能振荡反应机理进行了探讨．     

三角翼破裂涡流的非定常特性

为了研究飞机的三角翼前缘涡破裂后,破裂涡流的非定常特性,在风洞中进行了75°后掠三角翼的动态测压实验.实验结果表明:三角翼翼面的压力脉动强度变化和翼面上前缘涡的流态是正相关的,在前缘涡破裂迎角区,上翼面的压力脉动强度最高达到33 Pa,抖振强度随迎角的变化趋势与上翼面的压力脉动随迎角的变化趋势相同.通过对压力信号的分析得出,三角翼翼面上的压力脉动主要是由破裂涡流中的螺旋波引起的,螺旋波产生了三角翼机翼抖振.      

圆弧型风帆的阻力研究与计算

利用湍流基本定理，导出了圆弧型风帆的计算公式，计算结果与实验相符。     

航母关键系统对架次率的影响研究

航母舰载机的出动架次率是衡量航母及其航空联队作战能力的基本标准,是航母重要的战技指标。本文着重探讨了航母关键系统对架次率的影响,分析了弹射装置、着舰引导系统、飞机升降机、航空弹药贮运系统的能力对舰载机出动架次率的直接影响,对比了常规动力航母和核动力航母的加速性能对架次率的间接作用。     

散货船甲板室翼桥结构设计和振动分析

以某散货船甲板室的翼桥结构为研究目标,针对船型升级要求,提出4种不同的翼桥结构设计方案,采用有限元法计算不同方案下翼桥结构的固有频率与振动响应,与SMCR转速下主机缸频、螺旋桨叶频比较,验证是否避开机械设备工作频率,并从结构重量、固有频率,以及振动响应3个方面比较4个方案的性能参数,方案四比原方案重量有所减轻,结构固有频率躲避设备工作频率且留有较大频率余度,具有较好避振效果,最终选定方案四。     

Exact Solution of Unsteady Flow of Viscoelastic Fluid in a Pipe with Fractional Maxwell Model

The unsteady flow of viscoelastic fluid in a cylindrical pipe was investigated using the fractional Maxwell model. Two special cases of unsteady pipe flow were expressed. The first is start-up flow, and the second is oscillating flow. The exact solution of start-up flow under a constant pressure gradient was obtained by using the theories of Laplace transform and Fourier-Bessel series for fractional derivatives. The exact solution of oscillating flow was obtained by utilizing the separation of variables.