减阻剂对微胶囊相变悬浮液稳定性及粘度的影响

为了获得稳定性较高的微胶囊相变悬浮液,同时减少其流动阻力损失,配制了以异丙醇/水混合溶液为基液的微胶囊相变悬浮液,加入不同种类的减阻剂(PAM和CTAC),并采用旋转流变仪测试其粘度.结果表明:在实验温度为20℃,旋转流变仪剪切速率为0~100 L/s时,PAM减阻剂对微胶囊相变悬浮液的稳定性影响甚微,但会显著增大其粘度;CTAC减阻剂不能作为低浓度微胶囊相变悬浮液的减阻剂,质量浓度为10 w t.%的微胶囊相变悬浮液对应的CTAC最佳减阻浓度为200 mg/L.     

非流线型航行体超空泡减阻的实验分析和数值模拟

针对某水下航行体模型,在水洞内进行了自然状态和通气产生超空泡状态下的阻力试验,并用FLUENT6.0进行了数值模拟,依据比较结果分析和处理了实验数据,得到了自然和通气状态下非流线型水下航行体的阻力变化规律.结果表明,自然状态下非流线型航行体的阻力比流线型的大3倍多,但通气形成超空泡后可以大大降低航行体的阻力,并使减阻效果超过流线型航行体,从而达到更高的航速.     

超低界面张力驱油用表面活性剂的研究及应用

以十二烷基甜菜碱和脂肪酸酰胺两种表面活性剂为主要原料,研发了一种高活性、耐温、抗盐、超低界面张力的表面活性剂CS-6.实验结果表明:在40℃~80℃、矿化度10 000~100 000mg/L、表面活性剂溶液浓度0.3%~0.6%的情况下,油水间的界面张力均可达10-4mN/m数量级.同时该表面活性剂体系具有较好的乳化能力,且抗吸附性强,驱替实验效果良好.     

次氯酸钙溶液对磷化氢的吸收效果

研究了不同质量浓度的磷化氢以0.1 L/min的流速匀速通过次氯酸钙吸收液的吸收效果.研究结果表明,磷化氢经次氯酸钙吸收液吸收后浓度显著降低,磷化氢通过次氯酸钙吸收液的吸收效果与磷化氢在吸收液中有无搅拌、吸收液量和吸收液浓度有直接关系.随着磷化氢质量浓度的增大,次氯酸钙吸收液对磷化氢的吸收率逐渐降低,其中磷化氢质量浓度为0 mg/m L至500 mg/m L时,吸收率降低较快,由100%降低至93.1%,质量浓度为500 mg/m L至1 000 mg/m L时,吸收率变化较小,维持在93.1%和92.5%之间.增加搅拌、提高次氯酸钙溶液量和提高次氯酸钙溶液浓度均可以降低出气口磷化氢质量浓度,提高磷化氢的吸收率.     

等离子体控制翼型流动分离实验

为了提高等离子体的流动控制能力,在常规大气环境,来流风速分别为20m/s、30m/s、40m/s条件下进行了介质阻挡放电抑制NACA0015翼型流动分离实验研究。结果表明:等离子体能有效的抑制分离,实现增升减阻,但随着来流风速增加,有效控制的起始和终止攻角均变大,攻角区域却逐渐变小;可以通过在翼型分离点附近布置等离子体激励器,在允许的范围内尽量提高输入功率,使控制效果达到最佳。     

超空泡航行体加速段通气规律设计

利用高速射弹试验对超空泡的形态特性进行了研究,获得了空泡数与超空泡形态参数之间的拟合公式.以此为基础,结合相关文献中的空泡数与通气系数之间的经验公式等,对水下超空泡航行体加速段通气规律进行了系统研究,并给出了算例设计.设计结果表明,加速段速度从25 m/s增长到95 m/s的过程中,要求通气量在0.002~0.17 m3/s,而超空泡长度从0.57 m增长到2.24 m,覆盖模型的95%表面积,具有很好的理论减阻效果.     

尾翼楔角对通气超空泡特性影响试验研究

为优化通气超空泡航行体流体动力布局,通过水洞试验,研究了航行体尾翼对通气超空泡航行体流体动力的影响.细致分析了通气超空泡的生成和发展过程,给出了尾翼、尾翼楔角对通气超空泡航行体流体动力的影响规律.试验结果表明:航行体尾翼增大了通气超空泡航行体阻力系数与升力系数.通气超空泡航行体阻力系数与升力系数分别随自然空化数减小而减小.通气超空泡航行体阻力系数与升力系数随通气率增大先小幅增加后减小.尾翼楔角越大,通气超空泡航行体升力系数越大.     

伴随空化现象的细长体倾斜穿透水体过程研究

在自制的水下高速细长体发射装置上,进行了带攻角的细长体穿透水体的实验。利用高速摄影仪拍摄了细长体周围产生的空泡流以及细长体对自由液面的扰动,并且利用CFD数值模拟软件,模拟了细长体倾斜出水时与自由液面的相互作用。研究结果表明:当细长体以足够高的速度(37m/s)在水中航行时,会诱导产生超空泡;细长体在倾斜出水前后,速度会发生突增;细长体的平钝的尾部对自由液面隆起程度影响较大,尖锐头部对自由液面隆起程度影响较小。模拟结果与实验结果较为一致。     

生活污水与铜和铅对黄瓜种子萌发及其幼苗生长的影响

通过水培实验研究生活污水及铜和铅污染对黄瓜种子萌发及幼苗生长的影响.实验所设Cu2+质量浓度范围为25~300 mg/L,Pb2+质量浓度范围为100~500 mg/L.结果表明:低质量浓度的Cu2+、Pb2+溶液对种子生长无明显抑制效果,生活污水对黄瓜种子株高具有一定的促进作用,对根长则呈抑制作用.其中,低质量浓度(≤50 mg/L)的Cu2+溶液以及低质量浓度(≤200 mg/L)的Pb2+溶液均对黄瓜种子的萌发无明显抑制作用,黄瓜种子的发芽率、发芽势、发芽指数、活力指数、植株鲜质量均高于其他质量浓度.但随着Cu2+、Pb2+质量浓度的增加,对各项生长指标的抑制作用增强,且呈负相关.     

基于SST湍流模型的圆盘空化器超空泡特性仿真分析

基于全空化模型和SST k-ω湍流模型,对圆盘空化器的空化流动进行了仿真。首先,分析了平头回转体表面的压力分布,所得结果与Rouse和Mc Nown的试验结果符合良好,验证了文中数值方法的有效性。其次,计算得到了不同空化数下无攻角圆盘空化器的超空泡形态特性和阻力特性,并与经验公式进行比较,二者具有良好的一致性。最后,对带攻角圆盘空化器进行了仿真,分析了攻角对超空泡形态特性和流体动力特性的影响。研究表明空化数和攻角都对超空泡的主要尺寸有影响,而攻角还会对超空泡的对称性和回射流现象产生显著的影响,此外攻角对圆盘空化器的流体动力特性也有比较大的影响,尤其是对升力系数有着直接的影响。研究结果为圆盘空化器在水下航行体上的应用提供了参考。     

Effect of attack angle change on hydrodynamic character of supercavitating bodies

A series of experiments has been done in a moderate-velocity cavitation tunnel to investigate the effects of attack angle change on hydrodynamic characters of supercavitation. Hydrodynamic characters of the aft section at various attack angles were compared. The investigation shows that hydrodynamic forces of the aft section are dependent of supercavity shapes at different attack angles,and the magnitude of hydrodynamic forces of the aft section varies with the change of attack angle. When the aft section is in the fully wetted case,the drag coefficient changes little. Lift and moment coefficients both increase with the increased attack angle,and the increase magnitude is not large. When the aft body planing is on the cavity boundary,the drag coefficient of nonzero attack angle is larger than that of zero attack angle,and the maximal lift and moment coefficients both vary obviously with the increased attack angle. In the case that the body is fully enveloped by cavity,the drag coefficient,lift coefficient and moment coefficient are nearly constant with the change of attack angles.     

飞翼式碟形水下滑翔机流动与运动特性分析

为提高碟形水下滑翔机的水动力性能和滑翔经济性,提出一种新型飞翼式碟形自主水下滑翔机,采用计算流体力学中SST(shear stress transmission)湍流模型对其流体动力特性进行分析,得到其在0°~21°小攻角范围内升力系数、阻力系数、俯仰力矩系数以及升阻比的变化规律.并与模型实验结果进行对比,得出数值模拟结果与实验结果具有良好的一致性,验证了数值计算方法的有效性,且与传统水下滑翔机相比,飞翼式碟形自主水下滑翔机具有更优的综合水动力性能和滑翔经济性能.对于其运动特性,则基于多体动力学理论建立了该型水下滑翔机的动力学与运动学模型,并考虑了其内部纵向、横向调位滑块移动速度以及浮力驱动系统压载质量变化速度等调节变化的影响,代入数值仿真所得水动力系数,对该型水下滑翔机锯齿滑翔和螺旋滑翔等两种典型水下滑翔运动进行运动仿真.结果表明,该型水下滑翔机具有一定的运动稳定性,从理论上验证了其水下滑翔的可能.     

低渗透油藏驱油用耐温抗盐型表面活性剂研究

针对大庆油田M区块储层低孔、低渗、高温以及高矿化度的特点,采用常规表面活性剂往往不能取得较好的驱油效果。因此,以顺丁烯二酸酐、乙二胺和长链溴代烷为单体合成了一种新型双子表面活性剂SZ?11,并复配非离子型表面活性剂AEO?3,形成了一种适合低渗透油藏驱油用的耐温抗盐型表面活性剂驱油体系,并对其综合性能进行了评价。结果表明,该驱油体系具有良好的耐温性能和抗盐性能,在140 ℃下老化后,界面张力仍能达到0.008^{mN/m,体系在较高质量浓度的NaCl（150 000 mg/L）、CaCl₂（9 000 mg/L）和MgCl₂（2 500 mg/L）盐水中仍具有较低的界面张力;该驱油体系具有良好的乳化性能和润湿性能,可以通过乳化原油和改变岩石表面润湿性来提高驱油效率;储层天然岩心在水驱后注入0.4 PV表面活性剂驱油体系,能使岩心的采收率提高19.5%,具有良好的驱油效果。现场应用结果表明,实施表面活性剂驱油措施后,M区块内5口生产井日产油量明显提高,含水率下降,取得了良好的增油效果。}     

升力式再入飞行器全程三维自主制导方法

为增强升力式再入飞行器任务的灵活性,减少射前准备,实现快速发射和精确打击,研究一种升力式再入飞行器全程三维自主制导方法.首先,再入段制导提出通过再入走廊上下边界内插得到阻力加速度剖面,倾侧角采用两次反转的设计方法,通过调节阻力加速度剖面的内插值系数和倾侧角的反转点来满足约束和精度的要求;然后,下压段仅依靠飞行器当前信息和目标点位置采用比例导引的形式来设计导引律,并通过对导引系数的实时更新实现以一定的弹道倾角对目标的精度打击;最后通过对再入段和下压段衔接点处控制指令的平滑过渡,得到全程三维自主制导方法.蒙特卡洛打靶仿真结果表明,该制导方法能够导引飞行器在满足再入约束的情况下以规定的弹道倾角对目标实施精确打击,其中打击偏差小于10 m,弹道倾角偏差小于1.3°.     

Numerical exploration on jet oscillation mechanism of counterflowing jet ahead of a hypersonic lifting-body vehicle

Numerical investigation of a supersonic jet from the nose of a lifting-body vehicle opposing a hypersonic flow with the freestream Mach number being 8.0 at 40 km altitude was carried out by solving the three-dimensional, time-accurate Navier-Stokes equations with a hybrid meshes approach. Based on the analysis of the flow field structures and aerodynamic characteristics, the behaviours relevant to the LPM jet were discussed in detail, including the drag reduction effect, the periodic oscillation and the feedback loop. The obtained results show that the flow oscillation characteristic of the LPM jet is low-frequency and high-amplitude while that of the SPM jet is high-frequency and low-amplitude. Compared with the clearly dominant frequencies of the LPM jet, the SPM jet exhibits a broad-band structure. The LPM jet can sustain drag reduction effect until the angle of attack is 8°, and the lift-to-drag ratio of the vehicle is effectively improved by 6.95% at angle of attack of 6°. The self-sustained oscillation process was studied by a typical oscillating cycle of the drag force coefficient and the variation of the instantaneous pressure distribution,which reveals an off-axial flapping motion of the conical shear layer. The variation of the subsonic recirculation zone ahead of the vehicle nose strengthens the understanding of the jet behavior including the source of instability in the long penetration mode and the mechanism of the feedback loop. The aim of this paper is to advance the technology readiness level for the counterflowing jet applied as an active control technology in hypersonic flows by gaining a better insight of the flow physics.     

附加气动措施后箱梁断面三分力系数试验研究

通过节段模型风洞试验,研究某大桥各种抗风气动措施对静力三分力系数的影响,以期改善结构受力特性.以导流板位置、中央槽开孔率、栏杆透风率、检修车轨道位置、风障、车辆作为分析三分力系数的影响因素.研究表明:三分力系数的改变直接影响到静风荷载,这些参数的变化对主梁静风荷载的影响不容忽视.其中风障对主梁阻力系数的影响最为明显,在大攻角时主梁阻力系数在成桥有风障状态显著增大.     

变攻角火箭深弹空泡形态及阻力特性研究

利用Fluent软件对火箭深弹在不同攻角状态下的空泡形态及阻力特性进行研究。通过数值模拟的方式分析空化数及攻角对火箭深弹超空泡形态以及阻力特性的影响。研究结果表明,攻角越大,空泡的不对称性越明显,空泡的稳定性越差;火箭深弹的阻力系数、升力系数及力矩系数均随攻角增加而增大。火箭深弹攻角变化的仿真结果与水洞实验结果基本一致。     

Aerodynamic drag reduction of heavy vehicles using append devices by CFD analysis

Improving vehicle fuel consumption,performance and aerodynamic efficiency by drag reduction especially in heavy vehicles is one of the indispensable issues of automotive industry.In this work,the effects of adding append devices like deflector and cab vane corner on heavy commercial vehicle drag reduction were investigated.For this purpose,the vehicle body structure was modeled with various supplementary parts at the first stage.Then,computational fluid dynamic(CFD) analysis was utilized for each case to enhance the optimal aerodynamic structure at different longitudinal speeds for heavy commercial vehicles.The results show that the most effective supplementary part is deflector,and by adding this part,the drag coefficient is decreased considerably at an optimum angle.By adding two cab vane corners at both frontal edges of cab,a significant drag reduction is noticed.Back vanes and base flaps are simple plates which can be added at the top and side end of container and at the bottom with specific angle respectively to direct the flow and prevent the turbulence.Through the analysis of airflow and pressure distribution,the results reveal that the cab vane reduces fuel consumption and drag coefficient by up to 20 % receptively using proper deflector angle.Finally,by adding all supplementary parts at their optimized positions,41% drag reduction is obtained compared to the simple model.