Design of a Centrifugal Compressor with Low Solidity Vaned Diffuser(LSVD) for Large-Scale Compressed Air Energy Storage(CAES)

Compressed Air Energy Storage(CAES) has tremendous promotional value in the intermittent renewable energy supply systems. CAES has special requirements for compressor(e.g. heavy load, high pressure ratio, wide range). With advantages of higher efficiency and wider operation range, IGC(Integrally Geared Compressors) is selected to fulfill the special requirements of the large-scale CAES. To get a better aerodynamic performance, in this paper, based on the analysis of internal flow of centrifugal compressor, a multi-objective one-dimensional optimization design program was put forward combined with modified Two-Zone model and a low solidity vaned diffuser(LSVD) design method. Then, a centrifugal compressor aerodynamic component optimization design system was established with the three-dimensional blade optimization design method based on neural network and genetic optimization algorithm. Then a validation was done by redesigning the Krain-Impeller to get better performance. Finally, the aerodynamic design of the first stage of IGC was completed. The CFD calculation results indicated that the total-to-total pressure ratio of the first stage was 2.51 and the polytropic efficiency was 91.0% at the design point. What’s more, an operation margin and surge margin of the compressor was about 26.5% and 16.4% respectively.

HYDRODYNAMIC OPTIMIZATION DESIGN OF LOW SOLIDITY VANED DIFFUSER FOR A CENTRIFUGAL PUMP USING GENETIC ALGORITHMS

This paper presents a hydrodynamic redesign of the conventional vaneddiffuser into the low solidity varied diffuser for the maximum static pressure recovery in acentrifugal pump. A Bezier curve representation for profile description was coupled with ablade-to-blade flow calculation and a real-coded genetic algorithm. A low solidity vaned diffuser of0.89 in solidity was obtained through the present optimum design. Numerical analysis andexperimental test were made to evaluate the hydrodynamic performance of the centrifugal pump withthe designed low solidity vaned diffuser and original vaned diffuser. The obtained resultsdemonstrate that the centrifugal pump with the optimized vaned diffuser has compact size comparedwith the original one while the performance requirements have been met.

Numerical Investigation of the Centrifugal Compressor Stability Improvement by Half Vaned Low Solidity Diffusers

Centrifugal compressors for the fuel cell vehicles often operate near the surge line compared with the turbocharger compressors.Low solidity and half vaned diffusers are recognized as good ways to improve the stability of the centrifugal compressor.The presented work investigated four diffuser configurations (i.e.,the vaneless diffuser (VLD),full-height low solidity vaned diffuser (LSVD),hub-side half vaned diffuser (HVD) and shroud-side half vaned diffuser (SVD)) through steady-state and unsteady numerical simulations.The results show that the best performance is achieved by the LSVD,HVD and SVD at the design,surge and choke conditions.The flow rate at the surge operating point of the HVD has decreased by 15.53% compared with the LSVD,and 9.21% compared with the VLD.At near surge operating point,a longitudinal suction side passage vortex is formed on the hub of the LSVD and rotates as circumferential stall cells.A hairpin vortex is formed along the leading edge and is dragged by the main flow along the suction side as a local vortex shedding.The mechanism of the stability improvement by half vaned diffusers is that the tip leakage vortex migrates from the clearance side to the vane mounting side and replenishes the low-momentum zone on the mounting side.The best position where the half vaned diffuser should be mounted is based on the impeller outlet flow conditions,namely,the location of the wake region,where the meridional velocity and relative stagnation pressure is low.

A Real-coded Genetic Algorithm Applied to Optimum Design of a Low Solidity Vaned Diffuser for Diffuser Pinup

A numerical procedure for hydrodynamic redesign of the conventional vaned diffuser into the low solidity vaned diffuser by means of a real-coded genetic algorithm with Boltzmann, Tournament and Roulette Wheel selection is presented. In the first part, an investigation on the relative efficiency of the different real-coded genetic algorithm is carried out on a typical mathematical test function. The real-coded genetic algorithm with Boltzmann selection shows the best optimization performance compared to the Tournament and Roulette Wheel selection. In the second part, an approach to redesign the vaned diffuser profile is introduced. Goal of the optimum design is to search the highest static pressure recovery coefficient and low solidity vaned diffuser. The result of the low solidity vaned diffuser optimum design confirms that the efficiency and optimization performance of the real-coded Boltzmann selection genetic algorithm outperforms the other selection methods. A comparison between the designed low solidity vaned diffuser and original vaned diffuser shows that the diffuser pump with the redesigned low solidity vaned diffuser has the higher static pressure recovery and improved total hydrodynamic performance. In addition, the smaller outlet diameter of designed vaned diffuser tends to a more compact size of diffuser pump compared to the original diffuser pump. The obtained results also demonstrate the real-coded Boltzmann selection genetic algorithm is a promising optimization algorithm for centrifugal pumps design.

一种新型叶片扩压器的联合处理方法

以机翼扩压器为研究对象,对某船用涡轮增压离心压气机性能进行数值模拟.首先将扩压器叶片进行低稠度处理,在此基础上再进行叶片根部开槽处理,以研究低稠度与开槽联合处理对整机性能的影响.结果表明:低稠度处理可在全转速范围内拓宽流量范围,但失速边界发生整体右移;低稠度与开槽联合处理能够保持堵塞流量不变时,在全转速范围内增大失速裕度,在进一步拓宽流量范围的同时,解决失速边界偏移问题,可使高转速下稳定工作流量范围甚至超过无叶扩压器的2倍,但同时联合处理也降低了气动性能,仍高于无叶扩压器性能;槽道的径向位置是开槽处理的关键参数,除了影响流量范围大小外,还会使峰值效率点的绝热效率、总压比分别产生近4.0%、1.5%的波动,因而需优先确定.

基于进化算法和CFD技术的离心泵低稠度导叶的优化设计

结合离心泵导叶型线参数化方法、进化优化算法和Navier-Stokes方程求解技术对传统导叶进行了低稠度导叶优化设计。优化设计得到了稠度分别是0.89和0.65的导叶型线,数值验证表明:两种低稠度导叶的静压回复系数均高于初始设计。结合离心叶轮和优化设计得到的两种低稠度导叶进行了整个离心泵水力性能数值验证,计算结果表明:稠度是0.89的导叶的离心泵水力性能优于初始设计,而稠度是0.65的导叶的离心泵水力性能低于初始设计。研究结果表明对于初始设计的离心泵,采用优化设计得到的稠度是0.89的导叶具有更加紧凑的设计并且可以满足初始设计的要求。

低稠度半高叶片扩压器的模型级性能研究

通过数值模拟的方法研究了低稠度半高叶片扩压器在大流量离心压缩机模型级中的应用,并比较了其与无叶扩压器对模型级气动性能影响的差异。研究结果表明:采用低稠度半高叶片扩压器的模型级基本消除了盖侧附近低总压高熵值的区域,气动性能有较大提高。

离心压缩机低稠度叶片扩压器匹配设计方法研究

低稠度叶片扩压器(LSVD)在不损耗稳定工况范围的同时,具有较高的效率,应用广泛。本文以当量扩张角为判断依据,结合稠度的概念,提出一种LSVD设计方法,并基于两区域模型建立一种LSVD性能计算方法,完成大规模压缩空气储能系统离心压缩机大流量系数叶轮扩压器匹配设计。结果表明,基于两区域模型所建立的性能计算方法可以作为一维预设计的工具,并结合低稠度叶片扩压器设计方法,实现扩压器匹配设计;进口冲角在-3°^-2°时,离心压缩机整级性能较好,达到设计要求。