高负荷跨音压气机弯叶片的气动性能研究

通过商用计算流体软件对采用不同叶片弯曲形式设计的跨音压气机动叶进行了数值模拟,分析了叶片弯曲形式和弯曲角度对压气机效率的影响。详细讨论了在设计点弯设计对跨音压气机性能的影响,包括流动结构、负荷径向分布以及效率等。结果表明20°正弯设计将动叶设计点效率提高了0.42个百分点,正弯设计可以改善负荷的径向分布并抑制端壁角隅失速。     

基于数值优化的跨音速压气机动叶三维设计

实验验证了三维粘性流场求解程序,然后采用基于梯度法的数值优化程序对跨音压气机动叶积叠线进行优化设计,得到了弯掠结合的三维叶片,并对其进行了数值模拟及详细的流场分析.结果表明采用弯掠的三维动叶可以有效的改变叶片排内三维激波结构,降低尾迹损失,显著提高动叶的整体绝热效率,并使动叶具有更加良好的变工况性能.     

压气机1.5跨音级内部流动分析

对某轴流式压气机1.5跨音级进行了CFD数值模拟,分析了激波的结构、形状以及激波位置随运行工况变化的规律.研究发现在近失速工况下,动叶通道中出现强激渡,同时在静叶吸力面出现大分离.在近堵塞工况下,静叶根部通道喉部产生了激波,导致流动堵塞,静叶尾缘吸力面出现很强的二次流,使得压气机近堵塞工况损失很大,效率很低.     

动叶正弯对压气机性能影响的数值研究

对某多级高亚音轴流压气机的第七级动叶叶片进行了正弯设计的参数研究,得到了适用于所研究压气机的弯动叶气动性能变化规律,数值研究结果表明:对于正弯叶片,弯角和弯高存在一个最佳数值.动叶正弯改善了压气机级的气动性能,提高了整级的效率和压比.     

跨音轴流压气机气动设计与数值优化

介绍了带有进口导流叶片的三级跨音轴流压气机的气动设计与数值优化过程,气动设计采用准三维体系,包括一维平均流线设计、S2流面通流设计和任意中弧线叶片造型设计,并利用商用软件Numeca进行压气机流场分析.采用遗传算法结合人工神经网络的全局优化方法对第一级跨音动叶在多级环境下进行三维数值优化.结果表明:与优化前相比,优化后跨音级动叶叶尖的激波-边界层干涉损失明显降低,第一级动叶与三级压气机整机近设计点的绝热效率分别提高了0.87%和0.37%,压气机整机的质量流量、总压比、绝热效率和失速裕度均能够满足设计目标.     

弯掠动叶对压气机非定常性能影响的数值研究

对某多级高亚音轴流压气机的第七级原型级和弯掠动叶改型级进行了非定常数值模拟,研究非定常条件对两种压气机级总性能参数的影响,数值研究结果表明:非定常条件下,弯掠动叶级的绝热效率在每一瞬时都高于原型级,弯掠动叶级效率的非定常波动范围和幅值较原型级都有所降低,并且其非定常波动的相位发生了改变。     

进口气流角对某跨音级叶栅影响的数值分析

以某型大流量轴流压气机跨音级叶栅为研究对象,采用三维数值模拟方法分析了进口气流角的变化对跨音级叶栅流量特性及内部流场的影响。结果表明,随着进口气流角的增大,跨音级叶栅流量-效率和流量-压比特性线都向流量减小的方向偏移,并且动叶栅中激波的位置和强度的变化直接决定了跨音级叶栅压比和效率的变化。     

跨音速压气机中展弦比弯掠叶片气动性能影响的分析

将一跨音速静叶栅数值计算结果与实验结果进行了比较,表明计算与实验结果吻合的较好.为了讨论跨音速压气机中弯掠叶片适用的展弦比条件,在0°攻角下,展弦比为1.25、1.50和2.00,对0～30°弯掠叶片流场进行了数值分析,结果表明,当10°弯掠角时,小展弦比弯掠叶片对叶片性能影响较为明显;而在20°弯掠角时,大展弦比弯掠叶片对叶片性能影响较为明显.弯掠叶片使前缘激波转化为斜激波,并减弱了通道激波的强度,因而降低了叶栅激波损失.可以证明,在跨音速条件下展弦比的大小是如何使用弯掠叶片的一个重要的参考因素.     

弯掠动叶对压气机级静压系数的影响

对某多级高亚音轴流压气机的第七级原型级和弯掠动叶改型级进行了非定常数值模拟,数值研究结果表明:流动的非定常性对动叶尾缘和下游静叶前缘位置处的气动参数影响较为强烈,其中对静叶的影响要比对动叶的影响大.弯掠动叶减轻了非定常效应对动叶根部和顶部的影响,同时也减小了对下游静叶气动参数的非定常扰动.     

基于弯曲叶片的氦气轴流压气机优化设计

针对高负荷氦气压气机中角区分离、叶顶泄漏严重带来的效率损失问题，以单级氦气压缩机为研究对象，利用CFD方法，分析了不同弯曲角度下氦气压气机内部的角区损失和叶顶泄漏损失，并优化了现有五级轴流氦气压气机。结果表明：叶片正弯会增加端区处的静压，减少角区分离，进而降低角区损失；对动叶而言，在设计攻角下正弯也会增加前缘损失；动叶叶顶反弯使泄漏流远离下一个叶片的压力面，而合适的反弯角度可以降低叶顶泄漏量；选取合适的弯曲角度使五级轴流压气机设计点效率提高1.85%。     

跨声速压气机转子前缘积叠线的数值优化设计

采用数值优化方法对跨声速压气机转子NASA rotor37前缘积叠线进行了数值优化设计.本优化设计以绝热效率为目标函数,总压比与质量流量为约束条件,进行单目标有约束的优化设计.详细地分析对比了几何形状、总体性能及流场的变化.结果表明,叶片后掠并且加入弯曲,其激波的波形变得倾斜.在中部,强度有所削弱;在底部区域,激波有所后掠.同时指出,单一工况点的设计对变工况性能的控制能力不足.     

跨音速压气机叶栅中稠度对弯掠叶栅流场影响的数值分析

将一跨音速静叶栅数值计算结果与实验结果进行了比较,结果表明计算与实验结果吻合较好。为了讨论跨音速压气机中弯掠叶片的适用条件,在0°攻角下,稠度为1.75、1.50和1.25,对0~30°弯掠叶流场进行了数值分析,结果表明大稠度弯掠叶片的效果较为明显。弯掠叶片使前缘激波转化为斜激波,并减弱了通道激波的强度,因而降低了叶栅激波损失。可以验证在跨音速条件下稠度的大小是否在静叶栅中使用弯叶片的一个重要的参考因素。     

Aerodynamic sweeping study and design for transonic compressor rotor blades

<正>The objective of the present paper is to study the sweep effect on the blade design performance of a transonic compressor rotor.The baseline to be modified and swept is a designed well efficient transonic single rotor compressor. The first part of the present study is concerning the sweep effect with straight leading edge.In this case fixing the hub section the swept blade is formed by tilting the leading edge with whole blade forwards and backwards axially.The second part is to use an optimization strategy with simple gradient-based optimum-searching method and multi-section blade parameterization technique to search and generate an optimal swept rotor with curved arbitrary leading edge.Its adiabatic efficiency is a little bit greater than that of the reference un-swept rotor.     

Modeling and numerical investigation of the inlet circumferential fluctuations of swept and bowed blades

The circumferential fluctuation (CF) source terms induced by the inviscid blade force can affect the inlet distribution of flow parameters and radial equilibrium of swept and bowed blades. However, these phenomena cannot be adequately described by throughflow methods based on the axisymmetric assumption. A transport model for the CF stresses is proposed and correlated to the distribution of circulation to reflect the effect of the inviscid blade force. To investigate the effect of the inlet CFs on swept and bowed blades, the model is integrated into a throughflow model and applied to a series of cascades with different sweep and bow angles. For swept cascades, the CF source terms change the distributions of incidence angles, as well as the radial equilibrium at the inlet of the blade passage. And the influence is enhanced as the absolute value of the sweep angle increases. For bowed cascades, the distributions of incidence angles are also altered. For both cases, the model can offer a good prediction of the inlet CF source terms, and prove to exert a better prediction of blade design key parameters such as flow angles.     

A study of the unsteady tip flow field of a transonic compressor

An experimental investigation on the unsteady tip flow field of a transonic compressor rotor has been performed.The casing-mounted high frequency response pressure transducers were arranged along both the blade chord and the blade pitch.The chord-wise ones were used to indicate both the ensemble averaged and time varying flow structure of the tip region of the rotor at different operating points under 95% design speed and 60% design speed.The pitch-wise circumferential transducers were mainly used to analyze the unsteadiness frequency of the tip leakage flow in the rotor frame at the near stall condition.The contours of casing wall pressure show that there were two clear low pressure regions in blade passages,one along the chord direction,caused by the leakage flow and the other along the tangential direction,maybe caused by the forward swept leading edge.Both low pressure regions were originated from the leading edge and formed a scissor-like flow pattern.At 95% design speed condition,the shock wave interacted with the low pressure region and made the flow field unsteady.With the mass flow reduced,the two low pressure regions gradually contracted to the leading edge and then a spike disturbance emerged.     

Stall characteristics and tip clearance effects in forward swept axial compressor rotors

Tilting the blade sections to the flow direction (blade sweep) would increase the operating range of an axial compressor due to modifications in the pressure and velocity fields on the suction surface. On the other hand, blade tip gap, though finite, has great influence on the performance of a turbomachine. The present paper investigates the combined effect of these two factors on various flow characteristics in a low speed axial flow compressor. For this present study, nine computational domains were modeled; three rotor sweep configurations (0°, 20° and 30°) and for three different clearance levels for each rotor. Commercial CFD solver ANSYS CFX 11.0 is used for the simulations. Results indicated that tip chordline sweep is found to improve the stall margin of the compressor by modifying the suction surface boundary layer migration phenomenon. Diffusion Factor (DF) contours showed the severity of stalling with unswept rotor. For the swept rotors, the zones of high probable stall are less severe and they become less in size with increasing sweep. Increment in the tip gap is found to gradually affect the performance of unswept rotor, while the effect is very high for the two swept rotors for the earlier increments. As a minimum clearance is unavoidable, swept rotors suffer relatively higher deviation from the idealistic behavior than the unswept rotor due to tip clearance.     

Effect of Bowed/Leaned Vane on the Unsteady Aerodynamic Excitation in Transonic Turbine

To investigate the effect of bowed/leaned vane configurations on the aerodynamic performance and aerodynamic excitation in transonic high-pressure turbine, the full three-dimensional viscous unsteady numerical simulation was performed by solving N-S equations based on SAS SST method.The influence of bowed/leaned vanes on turbine efficiency and efficiency fluctuation was investigated. The action of vane modelling to the overall aerodynamic fluctuation level and the amplitude of each vane passing frequency were analyzed. By comparing instantaneous pressure fluctuation contours in the blade passage with space-time maps, the link of the pressure fluctuation on blade surface with flow distortions was achieved, which can reveal the mechanism of the impact of the vane modelling. As the results suggest, the turbine efficiency is promoted with positively leaned and bowed vane modelling, and the fluctuation of stage turbine efficiency is repressed, which contributes to the smooth running of the turbine stage. The blade aerodynamic excitation on the rotor blade is characterized by the motion of vane trailing edge shock system, and the vane configurations can reduce the fluctuation level on the rotor blade surface effectively. For the positively leaned vane configuration, the aerodynamic excitations at the root and tip region are affected by the impact of the amplitude of the first harmonic, whereas they are reduced with the decrease of the amplitude of the second and higher harmonics at midspan. For the positively bowed vane, aerodynamic excitation is repressed by reducing the amplitude of the third harmonic at the root region, and the first harmonic at the tip region, and the amplitude of each harmonic is reduced at the middle region.     

分流叶片前缘掠 对跨音速离心压气机气动性能的影响

对不同分流叶片前缘掠角(-20°~20°)的跨音速离心压气机流场进行了数值模拟研究,结果表明:分流叶片掠几乎不改变压气机的堵塞流量,前掠有扩展压气机工作范围、增加失速裕度的趋势,同时使性能提高,分流叶片前掠10°性能最佳,在最高效率点效率提高0.77%,压比提升0.91%;与原压气机相比,后掠性能有所下降。分流叶片掠对主叶片的影响集中在其叶片中部,对前端低能流体的径向迁移改善效果不明显;前掠使主叶片中部压差减小,减弱了通道中横向的压力梯度,减小间隙泄漏损失,后掠使泄漏损失增加;分流叶片掠对主叶片吸力面的斜激波影响甚微,对通道中部及其两侧的低能流体作用较明显,前掠抑制了压力面侧低能流团的发展,更好地改善了通道中部的分离流动,后掠使低能流团向分流叶片前积聚,流动损失增加。     

Aerodynamics of swept and leaned transonic compressor-rotors

A systematic investigation to understand the impact of axially swept and tangentially leaned blades on the aerodynamic behaviour of transonic axial-flow compressor rotors was undertaken. Effects of axial and tangential blade curvature were analyzed separately. A commercial CFD package, which solves the Reynolds-averaged Navier–Stokes equations, was used to compute the complex flow field of transonic compressor-rotors. It was validated against NASA Rotor 37 existing experimental data. Computed performance maps and downstream profiles showed a good agreement with measured ones. Furthermore, comparisons with experimental data indicated that the overall features of three-dimensional shock structure, shock-boundary layer interaction, and wake development are calculated well by the numerical solution. Next, quite a large number of new transonic swept rotors (26) were modelled from the original Rotor 37, by changing the meridional curvature of the original stacking line through three previously defined control points (located at 33%, 67% and 100% of span). Similarly, 26 new transonic leaned rotors were modelled by changing the circumferential position of the same control points. All the new transonic rotors were simulated and the results revealed many interesting aspects which are believed to be very helpful to better understand the blade curvature effects on shock structure and secondary losses within a transonic rotor.