容腔泄漏流对环形扩压叶栅性能的影响

为探究容腔泄漏流对环形扩压叶栅气动性能及流场结构的影响,基于验证的数值模拟方法对环形扩压叶栅进行研究,分析泄漏流流量、周向速度大小对角区分离和总压损失的影响。结果表明,随着泄漏流量增加,通道涡PV扩展范围变大,角区分离提前出现,叶栅总压损失系数逐渐增加,当泄漏流量系数增大至1.5%时,总压损失系数增加22.9%;泄漏流周向速度的增加改善了近端壁区域堵塞情况,贴近端壁的流体向吸力面偏转程度减弱,偏移范围减小,当周向速度系数增大至1.1时,总压损失系数降低21.3%。

不同来流附面层厚度下容腔泄漏流对围带式静叶性能影响

基于验证的数值模拟方法,针对带容腔结构的围带式静叶,研究了容腔泄漏流对其性能的影响以及容腔泄漏流与主流的相互干涉作用。在不同的来流附面层厚度下,探讨了叶栅二次流运动和角区分离发展情况,并通过总压损失系数和熵增系数对性能变化进行评判。结果表明:附面层厚度的增加使无容腔扩压叶栅总压损失系数和熵增损失系数增加。容腔泄漏流使叶片前缘出现容腔泄漏涡,并对通道涡的发展和集中脱落涡的大小产生影响;同时容腔泄漏流加强了叶栅通道内的三维流动效应,削弱了近端壁面流体的横向偏转;随着附面层增厚,带容腔的扩压叶栅的总压损失系数和熵增损失系数变化程度不明显。

Influence of Cavity Leakage flow on Corner Separation in a Shrouded Stator Cascade

The impacts of the cavity leakage flow on the shrouded stator aerodynamic performance were investigated by modelling the annular cascade mainstream with the seal cavity flow path based on the validated numerical method.Meanwhile,the interactions between the cavity leakage and the mainstream were also determined in the current study.The development of hub corner separation under the action of leakage was discussed and the total pressure loss coefficient as well as the entropy-based loss coefficient was employed to evaluate the performance changes at different seal clearances and cavity rotational speeds.The results show that the cavity leakage flow induces a new vortex near the blade leading edge and plays an important role in the development of passage vortex and the size of concentrated shedding vortex.By increasing the seal clearance with more cavity leakage flow rate,an increase in the pitchwise extent of the separation region under 15%span is significant and the total pressure loss in the separation core increases.In addition,with the increase of cavity rotating speed,the starting point of corner separation moves backward,reducing the size and depth of the hub corner separation.The mainstream loss reduction in combination with the entropy increase in the seal cavity causes the entropy-based loss coefficient to perform a trend of decreasing first and then increasing with the cavity speed.

旋流和风阻温升下压气机级间篦齿封严空气网络计算模型

以压气机级间篦齿封严结构为研究对象,将封严系统简化为典型元件组成的空气网络,建立相应的元件流动特性计算模型。篦齿封严泄漏特性计算模型中没有考虑旋流和风阻温升影响的问题。特别采用一维流基本方程组进行描述旋转盘腔内的旋流,转子壁面摩阻应用经验关系式计算,方程组采用龙格-库塔法求解。旋转盘腔一维工程计算获得其旋流速度和风阻温升分布。根据旋流速度的大小,采用面积修正法对篦齿封严的泄漏特性计算方法进行了修正,并通过考虑流体物性随沿程温度变化来考虑风阻温升的影响。考虑旋流与温升的泄漏流量计算结果与数值计算结果最大相差1.4%,而不考虑旋流及风阻温升时最小偏差为9.9%,最大偏差为20.1%。一维工程计算结果与实验结果进行了对比,两者吻合良好,相对偏差不超过7%。计算中采用实测的篦齿间隙,该间隙通过在旋转篦齿实验中测量转子的转动变形与受热膨胀,以及机匣的热变形而获得。

Performance Analysis of Inter-Stage Leakage Flows at Rotating Conditions in an Axial Compressor

For the compressor with shrouded stator blades,the stator well is a rotor-stator space between the rotating drum and the stationary shroud.Due to the pressure difference,a reverse leakage flow would travel through the stator well and inject into the main flow path.Although,the labyrinth seal is commonly placed under the shroud,the rotation effect and seal clearance variation in actual operation process have great impact on the characteristics of this inter-stage leakage,as well as the compressor performance.In this paper,experiments were conducted at a compressor inter-stage seal test rig.The leakage flow rates,total temperatures and swirl ratios were obtained at different speeds and working clearances.The proportions of rotation effect and the clearance reduction effect were analyzed by data processing.Comparisons indicate that the working clearance and leakage flow reduce about 43%and 50%respectively,when the rotational speedω=8100 r/min.The proportion of reduction caused by the rotation effect is around 15%,while the influence of working clearance variation is much greater,accounting for about 35%.The windage heating coefficient and swirl ratio in the outlet cavity are almost in exponential relationship with the rotor speed.The increases in total temperature and swirl ratio generated by the rotation effect are found to be about 80%.In addition,the swirl and radial velocity profiles in the cavities were discussed by validated numerical simulations to reveal the typical flow characteristics.The data presented can provide guidance for better leakage conditions prediction as well as the inter-stage seal design enhancement.