摘要
叶顶采用双凹槽结构是一种通过有效阻碍叶顶泄漏流进而改善叶轮性能的措施之一。基于FLUENT数值模拟软件,以OB-84型动叶可调式轴流风机为研究对象,模拟风机在原叶顶及三种不同开槽深度的双凹槽叶顶下的性能,探讨间隙内部及其附近泄漏流场变化及损失分布特征;并利用ANSYS有限元动态分析模块校核原叶顶及双凹槽叶顶时叶片的振动特性。研究表明:双凹槽叶顶结构改善了泄漏流场的分布,阻碍了泄漏流的发展,削弱了泄漏流与主流的掺混;采用双凹槽叶顶结构后风机性能发生显著变化,设计工况下风机全压有所下降,同时效率得到一定程度的提高;开槽深度对风机性能的影响在设计流量附近较为显著,而在大流量下对风机性能影响较小;设计工况下叶顶开槽深度为3 mm时风机具有最优的性能,效率较原风机提高了1.05%,喘振裕度也有所改善。叶片振动特性的校核结果表明双凹槽叶顶下叶片各阶固有频率较原叶顶时均有所增加且避开了叶片通过频率,即采用双凹槽叶顶结构不会引发叶片共振。
Adopting double grooved blade tip structure is one of the measures to improve the impeller performance by blocking the tip clearance leakage flow effectively. Basing on a variable pitch axial flow fan of OB-84 type, the performance of the fan with original blade tip and three double grooved blade tips with different groove depth are simulated by using numerical software FLUENT. Both the leakage flow field and loss distribution in and near the tip clearance are discussed. The vibration characteristics of original blade and double grooved blade tips are also checked with ANSYS finite element dynamic analysis module. The results reveal that double-grooved blade tip structure improves the distribution of leakage flow which hinders the development of leakage flow and thus impairs the mixing of the leakage flow and passage flow. The performance of the fan with double grooved blade tips varies significantly with a decrease in total pressure and an increase of efficiency to some extent under the designed operating condition. The impact of groove depth on fan performance is prominent in the vicinity of design flow rate while little influence in large flow rate. The double groove blade tip with a depth of 3mm obtains the optimal performance with an improvement of efficiency by 1.05 percent greater than the original fan at design condition and an improvement of surge margin. The characteristics of blade vibration show that each order natural frequency of double grooved blade is increased compared with the original blade and is out of step with the blade passing frequency, so the resonance will not occur by adopting double grooved blade tip.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2015年第4期167-174,共8页
Journal of Mechanical Engineering
基金
河北省自然科学基金(E2012502016)
中央高校基本科研业务费专项基金(13MS98)资助项目
关键词
轴流风机
双凹槽
开槽深度
气动性能
振动特性
axial flow fan
double groove
groove depth
aerodynamic performance
vibration characteristic
