Design efficiency optimization of one-dimensional multi-stage axial-flow compressor

A model for the optimal design of a multi-stage compressor, assuming a fixed configuration of the flow-path, is presented. The absolute inlet and exit angles of the rotor, the absolute exit angle of the stator, and the relative gas densities at the inlet and exit stations of the stator, of every stage, are taken as the design variables. Analytical relations of the compressor elemental stage and the multi-stage compressor are obtained. Numerical examples are provided to illustrate the effects of various parameters on the optimal performance of the multi-stage compressor.     

船用燃气轮机低压压气机气动布局规律研究

为缩短燃气轮机低压压气机的设计周期,获取一维设计中各关键设计参数分布规律,同时得到最优的一维设计参数选取方案,采用基于HARIKA算法的压气机一维设计与分析程序对某型船用低压压气机流量系数、载荷系数和反动度的轴向布局方法进行了研究并提炼了各参数分布的数学模型。其中,流量系数和载荷系数沿级分布为近似单峰值的三次多项式曲线,反动度分布为"二段式",通过改变流量系数和载荷系数的峰值点坐标和改变特定级反动度和反动度变化步长的方法,研究了不同布局方式对效率、喘振裕度以及压比的影响,最后结合优化算法得到了最优参数分布方案。结果发现:流量系数峰值位置在第6级,载荷系数在第5级或第6级时效率和喘振裕度性能较好;第四级反动度取值0.5～0.52时效率较高;相比载荷系数和反动度,流量系数对非设计工况性能影响更为显著,优化后的参数分布方案在各转速下喘振裕度均有所提高。     

Investigation into the influence of diffuser stagger angles on the flow field and performance of a centrifugal compressor

The performance graphs of a centrifugal compressor under different diffuser stagger angles were measured, and the influence of different stagger angles of vanes on the stage performance as well as flow field was investigated numerically. The results show that the performance graph shifts when the diffuser stagger angle is altered; the influence of different stagger angles of vanes on the flow field inside the centrifugal compressor is great. Large scale vortices appear on the diffuser vane under larger incidence. An optimal diffuser stagger angle should exist at a specified flow rate to make the characteristic of the flow optimized. The incidence corresponding to the highest efficiency is not 0° at the design condition. Translated from Journal of Engineering Thermophysics, 2006, 27(1): 61–64 [译自: 工程热物理学报]     

某型多级轴流压气机三维CFD流场分析及气动优化

以某11级轴流压气机为研究对象,通过三维计算软件对某型压气机整机建模及流场进行了数值模拟,分别计算了设计工况、变工况及改变导叶安装角等工况的特性,得到了压气机流量－压比特性曲线、流量－效率特性曲线,与压气机的性能试验数据进行了对比,其误差在可允许范围内.同时对压气机的每一级的数据行了分析,总结了该压气机的气动设计规律.通过流场分析得到出口导叶的流场分布不合理的结论,并通过对其母型机的流场分析,提出了改进的方案.这些工作对压气机的设计开发提供了宝贵经验.     

低工况下轴流压气机可转导叶调节规律研究

以某型两级跨音速轴流压气机为研究对象,采用实验及数值模拟方法,针对非设计转速下可转导叶调节角度对压气机工作稳定性的作用规律展开研究。首先,通过与实验结果进行对比,验证了数值模拟方法的有效性。其次,对三种不同调节角度下的压气机稳定工作裕度及内部流动机理进行了深入分析。结果表明:随着安装角由正到负调节,效率-流量曲线总体向左移动,压比-流量曲线向左下方移动,当可转导叶调节角度为-8°时,压气机喘振裕度由0°时的7.71%增加到8.24%。     

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%。     

给定轴分速时轴流压气机级性能的解析优化

用一维理论对轴流压气机的初步设计作进一步的研究,导出了轴流压气机基元级的特性关系,建立了在给定轴向分速时最优化设计的数学模型,得到了解析关系,所得结论具有很好的普适性,并可进一步拓广用于多级轴流压气机优化中。     

The effect of variable stator on performance of a highly loaded tandem axial flow compressor stage

Increasing the aerodynamic load on compressor blades helps to obtain a higher pressure ratio in lower rotational speeds.Considering the high aerodynamic load effects and structural concerns in the design process,it is possible to obtain higher pressure ratios compared to conventional compressors.However,it must be noted that imposing higher aerodynamic loads results in higher loss coefficients and deteriorates the overall performance.To avoid the loss increase,the boundary layer quality must be studied carefully over the blade suction surface.Employment of advanced shaped airfoils (like CDAs),slotted blades or other boundary layer control methods has helped the designers to use higher aerodynamic loads on compressor blades.Tandem cascade is a passive boundary layer control method,which is based on using the flow momentum to control the boundary layer on the suction surface and also to avoid the probable separation caused by higher aerodynamic loads.In fact,the front pressure side flow momentum helps to compensate the positive pressure gradient over the aft blade's suction side.Also,in comparison to the single blade stators,tandem variable stators have more degrees of freedom,and this issue increases the possibility of finding enhanced conditions in the compressor off-design performance.In the current study,a 3D design procedure for an axial flow tandem compressor stage has been applied to design a highly loaded stage.Following,this design is numerically investigated using a CFD code and the stage characteristic map is reported.Also,the effect of various stator stagger angles on the compressor performance and especially on the compressor surge margin has been discussed.To validate the CFD method,another known compressor stage is presented and its performance is numerically investigated and the results are compared with available experimental results.     

最大厚度位置对高亚音轴流压气机叶型设计的影响

为了在具有不同负荷的压气机叶栅的初始设计过程中选取最大厚度位置,采用数值方法对在不同折转角的高亚音来流条件下对扩压叶栅进行了大量的系统性研究,分析了最大厚度位置、折转角以及稠度3个叶栅几何参数对叶栅变冲角特性以及对最小损失冲角下的叶栅气动性能的影响规律.基于大量叶栅样本建立数学模型,用来定量描述最小损失冲角,以及最小损...     

变弯度叶栅的试验研究

对有缝隙的和无缝隙的变尾缘叶栅与变弯度叶栅进行了系统试验研究,取得了这种叶栅的气流转折角和损失以及落后角的变化规律。证实压气机变弯度叶栅可在较小的能量损失下实现较大的气流转折角,其工作特性比可转导叶明显优越。推荐的叶栅构型及其几何参数值可供设计直接使用,它是改善压气机调节性能,防止喘振,扩大稳定工作范围的行之有效的方法。     

Numerical Investigation of Base-Setting of Stator’s Stagger Angles for a 15-stage Axial-Flow Compressor简

A 15-stage axial-flow compressor utilized in steel industry was studied in this paper. All the stator＇s stagger an- gles of the compressor are variable to ensure the multistage compressor operate effectively within a wide range of flow rate and meanwhile satisfy the demand for sufficient pressure ratio, adiabatic efficiency and stall margin. Three in all different base-settings of stator＇s stagger angles were presented and commercial CFD soft-ware was applied to obtain the overall performance characteristics. The results showed that both of the optimized base-settings improved the performances both in summer and winter conditions, although the adiabatic efficiency was somewhat decreased. Taking incidence angle and stage loading into consideration, differences among the three cases were analyzed in detail. On the basis of numerical computations, the performance could be effectively improved through adjusting the base-setting of stator＇s stagger angles.     

Investigation of non-axisymmetric endwall contouring in a compressor cascade

The current paper presents experimental and computational results to assess the effectiveness of non-axisymmetric endwall contouring in a compressor linear cascade. The endwall was designed by an endwall design optimization platform at 0° incidence(design condition). The optimization method is based on a genetic algorithm. The design objective was to minimize the total pressure losses. The experiments were carried out in a compressor cascade at a low-speed test facility with a Mach number of 0.15. Four nominal inlet flow angles were chosen to test the performance of non-axisymmetric Contoured Endwall(CEW). A five-hole pressure probe with a head diameter of 2 mm was used to traverse the downstream flow fields of the flat-endwall(FEW) and CEW cascades.Both the measured and predicted results indicated that the implementation of CEW results in smaller corner stall,and reduction of total pressure losses. The CEW gets 15.6% total pressure loss coefficient reduction at design condition, and 22.6% at off-design condition(+7° incidence). And the mechanism of the improvement of CEW based on both measured and calculated results is that the adverse pressure gradient(APG) has been reduced through the groove configuration near the leading edge(LE) of the suction surface(SS).     

Optimal ratio of bend channel in centrifugal compressor

A numerical investigation on the flow in a bend channel by coupling the impeller with the vaneless diffuser in a centrifugal compressor with different r/b ratios (bend radius r to bend channel width b) is presented. The jet-wake effect of the impeller outlet is considered and flow pattern in the bend channel and the performance of the centrifugal compressor stage are investigated. The results indicate that there is an optimal r/b ratio for increasing the stage efficiency to the highest for a specific compressor stage. The change in r/b ratio significantly affects the flow angle of the bend channel outlet. The prime reason for the total pressure loss in the bend channel is the wall friction in the bend channel.     

某F级燃气轮机压气机跨音级特性计算

本文作为某F级燃气轮机轴流压气机整机特性计算的一部分,考虑到跨音级存在激波及其与附面层的相互干涉、动叶叶顶泄漏等复杂的流动现象,针对该压气机的跨音级(第一级)进行单独计算.采用NUME-CA软件对压气机内部流场进行数值计算.实际计算表明:文中使用的方法可以很好地计算出压气机全工况特性.选取近失速点、近设计点、近堵点,对...     

Aerodynamic Performance Improvement of a Highly Loaded Compressor Airfoil with Coanda Jet Flap

Coanda jet flap is an effective flow control technique,which offers pressurized high streamwise velocity to eliminate the boundary layer flow separation and increase the aerodynamic loading of compressor blades.Traditionally,there is only single-jet flap on the blade suction side.A novel Coanda double-jet flap configuration combining the front-jet slot near the blade leading edge and the rear-jet slot near the blade trailing edge is proposed and investigated in this paper.The reference highly loaded compressor profile is the Zierke&Deutsch double-circular-arc airfoil with the diffusion factor of 0.66.Firstly,three types of Coanda jet flap configurations including front-jet,rear-jet and the novel double-jet flaps are designed based on the 2D flow fields in the highly loaded compressor blade passage.The Back Propagation Neural Network(BPNN)combined with the genetic algorithm(GA)is adopted to obtain the optimal geometry for each type of Coanda jet flap configuration.Numerical simulations are then performed to understand the effects of the three optimal Coanda jet flaps on the compressor airfoil performance.Results indicate all the three types of Coanda jet flaps effectively improve the aerodynamic performance of the highly loaded airfoil,and the Coanda double-jet flap behaves best in controlling the boundary layer flow separation.At the inlet flow condition with incidence angle of 5°,the total pressure loss coefficient is reduced by 52.5%and the static pressure rise coefficient is increased by 25.7%with Coanda double-jet flap when the normalized jet mass flow ratio of the front jet and the rear jet is equal to 1.5%and 0.5%,respectively.The impacts of geometric parameters and jet mass flow ratios on the airfoil aerodynamic performance are further analyzed.It is observed that the geometric design parameters of Coanda double-jet flap determine airfoil thickness and jet slot position,which plays the key role in supressing flow separation on the airfoil suction side.Furthermore,there exists an optimal combination of front-jet and rear-jet mass flow ratios to achieve the minimum flow loss at each incidence angle of incoming flow.These results indicate that Coanda double-jet flap combining the adjust of jet mass flow rate varying with the incidence angle of incoming flow would be a promising adaptive flow control technique.     

地面重型燃气轮机压气机叶型的优化设计

将优化理论引入压气机叶型设计,建立了具有自动优化设计能力的平台。该平台由自主开发的二维叶型生成程序、网格生成软件Gambit、流场计算分析软件CFX以及自主开发的优化模块组成。以某地面重型燃气轮机压气机叶型为优化对象,以总压损失系数为目标函数,流场分析中考虑转捩情况。优化设计之后,叶型气动性能有较明显改善。设计工况下叶型总压损失系数较原型下降了3.63%,非设计工况下的性能也优于原型。     

船用燃气轮机压气机多级可调静叶优化匹配方法研究

作为防止燃气轮机喘振的有效手段之一,可调静叶技术的应用能够提升压气机在非设计工况下的效率和运行范围,从而提高燃气轮机变工况下的经济性和稳定性.以某型船用三轴燃气轮机为研究对象,建立压气机一维性能分析模型与燃气轮机零维仿真模型耦合的变维度燃气轮机仿真模型,以经济性和稳定性为优化目标,通过多目标遗传算法对低压压气机多级可调...     

超临界氦气离心压气机流场分析

设计了一个包含离心叶轮、扩压器和回流器的单级超临界氦气离心压气机,并采用数值模拟方法对设计结果进行了三维数值模拟分析。通过对总特性、叶表压力分布、展向参数分布以及三维流场的分析,得到了高负荷超临界氦气离心压气机各部件内部的典型复杂流动特点。研究结果表明：相比常规工质,超临界氦气离心压气机单级压比较低,但叶轮与扩压器的负荷和级效率较高,且超临界氦气整体流动为亚音流,只在叶片前缘局部出现超音区。     

船用燃气轮机低压压气机改型设计研究

为了保证船用8级低压压气机在低工况稳定性不降低的前提下,同时提高设计点效率,通过数值模拟的方法研究展弦比优化对压气机设计点效率的影响。分析结果表明：展弦比的选取会影响主流区的流动损失和端壁二次流损失,进而影响压气机性能。优化了多级压气机后面级展弦比,将设计点效率提高了0.42%。同时,通过优化可转导叶偏转角度,确保了60%转速的喘振裕度不降低。     

新型变几何导叶试验研究

本文通过一系列平面叶栅试验,得出轴流压气机可变尾缘进口导叶的气动特性。该特性优于可转导叶的特性,损失系数小于可转导叶。提出变尾缘叶栅几何参数选取原则及其最佳值范围。按最佳参数构成的这种叶栅,气流转折角和损失系数很接近常规大弯度光滑叶型的数值,宜代替可转导叶作为压气机进口导叶。试验结果可直接应用于设计。