关于对称翼型气动特性数值模拟的研究

针对NACA0012、NACA0015、NACA0018这3种翼型的绕流流动,建立二维湍流模型,利用Fluent软件对翼型不同来流攻角下的气动特性进行数值模拟计算。湍流模型采用SST k-ω模型处理,得出雷诺数在0.82×106时翼型的升阻系数、升阻比随来流攻角的变化关系,并与相对应的翼型试验数据对比,验证了数值模拟的可靠性。结果表明,NACA0018翼型与其他2种翼型相比,具有较高的升力系数、升阻比和更好的失速性能。

某型无人机全机气动力数值计算

使用三维造型软件和计算流体力学软件对某型无人机进行了气动力数值模拟,得到小迎角范围内的升、阻力系数和力矩系数以及无人机表面的压力、密度和来流速度分布情况,同时,对该无人机进行了气动力的工程经验估算,并将估算结果与数值计算结果进行对比分析.研究表明,数值计算能够较好的模拟小尺度低速流场流动,对无人机的研制能起到重要的作用.计算结果为下一步无人机的气动外形优化设计提供了理论依据和重要参考.

头端整流雷体绕流数值模拟

低速不可压绕流中,头部形状明显影响鱼雷或UUV的流体动力特性。针对头部平端面上装设小整流锥的钝头形状雷体,采用Fluent流体分析软件,数值模拟雷体低速绕流流场特性。在0°~5°迎角范围内计算获得雷体压强分布和速度分布及运动阻力和升力系数,讨论分析结果并给出了详细模拟计算过程。

叶片翼型结冰形态及其气动特性

针对风力机叶片翼型形状对结冰过程的影响及其导致的气动特性变化问题,采用欧拉法及热传质原理构建叶片结冰过程的数学模型并进行数值模拟分析。以NH02系列翼型族为例,建立翼型曲率特征模型,研究叶片关键参数如最大厚度对结冰量的影响机制,预测了某翼型在不同工况下的冰形及位置,探究了干净与结冰翼型的升、阻力特性变化规律。结果表明,结冰量与叶片的相对厚度及最大相对厚度所在位置呈正相关性;结冰导致升力系数变化范围为5%~20%,阻力系数为干净翼型的1.4~2.45倍;结冰致使翼型失速迎角变小,翼型提前进入失速状态。

Relevance of zero lift drag coefficient and lift coefficient to Mach number for large aspect ratio winged rigid body

Synthetic analysis is conducted to the wind tunnel experiment results of zero lift drag coefficient and lift coefficient for large aspect ratio winged rigid body.By means of wind tunnel experiment data,the dynamics model of the zero lift drag coefficient and lift coefficient for the large aspect ratio winged rigid body is amended.The research indicates that the change trends of zero lift drag coefficient and lift coefficient to Mach number are similar.The calculation result and wind tunnel experiment data all verify the validity of the amended dynamics model by which to estimate the zero lift drag coefficient and lift coefficient for the large aspect ratio winged rigid body,and thus providing some technical reference to aerodynamics character analysis of the same types of winged rigid body.

绿色无动力渡船设计及参数优化研究

在所设计的绿色无动力船的基础上,对动力板截面进行了修型,并数值模拟了水流速为5m/s、船以各级速度行驶时的受力情况;结果表明,经平底修型后增大了翼型的弯度,明显改善了压力面分布,增大了升力系数以及船以各级速度行驶时对应的升阻组合系数。

Flow Characteristics in an External-Loop Airlift Slurry Reactor

The local flow characteristics in an external-loop airlift slurry reactor were investigated.The axial profiles of the local gas holdup,the Sauter mean diameter and the rise velocity were obtained.It was found that the bubble size and rise velocity were influenced by the solid holdup,and the bubble coalescence was enhanced by the increase of the solid holdup.A new correlation was used to predict the slip velocity between the gas phase and the slurry phase by taking into account the local gas holdup,the bubble size,and the physical properties of the experimental system.By using this correlation,the local drag coefficient can be calculated in the bubble swarm.

微孔对翼型水力特性影响探讨

应用ICEM、FLUENT、CFX(通过ISO认证的CFD模型)等软件,采用标准的k-ε模型,制成水力机械对称翼型叶片,并在其叶片的几何模型低压区断面上,布置种类为全通Ф28、Ф36、Ф63多微孔、半通单孔和全通单孔,进行绕流数值模拟分析。根据压强分布、升力系数、阻力系数和升阻比系数等变化因素判断了孔的数量及深度对翼型的空化性能和水力性能的影响关系。研究结果表明:在翼型的低压高速区工作面布置一定数量的微孔能有效增加压强,从而减小空化,且36孔翼型低压区范围最小、升阻比系数最大;在低压区打孔能够明显减小阻力,且1孔半、1孔全通模型阻力是无孔翼型阻力的39%和44%;微孔模型翼型升力有所下降;半通孔的阻力系数低于全通孔,且升力系数略高于全通孔。半通孔和全通孔的升阻比相对于无孔提高了2倍和1.7倍,进而改善翼型的水力特性,因此,孔采用半通方式优于全通方式。