共查询到20条相似文献,搜索用时 31 毫秒
1.
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. 相似文献
2.
Xi Guang Zhou Li Ding Haiping Yuan Minjian Zhang Chunmei 《Frontiers of Energy and Power Engineering in China》2007,1(3):290-294
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] 相似文献
3.
Xiao Jun Gu Chuangang Shu Xinwei Gao Chuang 《Frontiers of Energy and Power Engineering in China》2007,1(4):473-476
The flow in a centrifugal compressor stage with variable inlet guide vanes (VIGVs) is investigated by numerical simulation
in this paper. Analysis of the performance curves and relative velocity vectograms indicates that performance curves shift
toward small flow domain when VIGVs turn positively, and toward large flow domain when VIGVs turn negatively. Stage efficiency
drops quickly after work condition enters a small flow domain through the peak efficiency point. Under the circumstance of
large setting angles of the guide vanes, there exist obvious flow separations in guide vane passages within wide flow ranges,
and back flow regions can be located at the front of splitter suction surfaces under large flow conditions, while under the
condition of small flow, flow separations occur on suction surfaces of long blades.
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Translated from Journal of Power Engineering, 2006, 26(6): 804–807 [译自: 动力工程] 相似文献
4.
Jianfeng LI Junfu LU Hai ZHANG Qing LIU Guangxi YUE 《Frontiers of Energy and Power Engineering in China》2008,2(4):438-442
For a deeper understanding of the flow characteristics in the high-pressure centrifugal blower of a fan of Model 9–26 with
splitter blades, a three dimensional (3-D) numerical simulation of air flows in the fan was conducted with FLUENT software.
The standard k-ε turbulent model and unstructured grids were used. The computational fluid dynamics (CFD) results showed that the performance
of a fan could be improved by adding the splitter blades in the channel among the leaf blades. Under operational conditions,
with the presence of splitter blades, the air flow rate of the fan increased about 5% and the total pressure at the outlet
of the fan increased about 10% on average. It was also found that the length of the splitter blades affected the air flow
and pressure drop. There is an optimal value for the length. The simulation results provide helpful information for improving
the fan performance.
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Translated from Fluid Machinery, 2007, 35(10): 29–32 [译自:流体机械] 相似文献
5.
氦气离心压气机是预冷发动机氦回路的核心部件,但国内对氦气离心压气机的相关探究较少。为探究氦气离心压气机的压比设计方法,从离心压气机进口和出口速度三角形的角度,分析了出口安装角、滑移因子以及进气负预旋对叶轮做功的影响。提出了基于低出口安装角、高滑移因子和进气负预旋的高压比设计方法。根据此方法设计出了总压比为2.521、等熵效率为83.2%、喘振裕度为18.55%的氦气离心压气机,并通过数值模拟的方法对此压气机的气动特性以及流场进行了分析,证明了高压比设计方法的可行性。 相似文献
6.
Numerical investigation is implemented on aerodynamic performance inside the crossover and de-swirling cascade of a multistage
centrifugal compressor. The emphasis is put on the aerodynamic performance influenced by the circumferentially pre-swirling
coming flow. The results indicate that flow separation occurs inside the crossover, and the separation area may be changed
with different circumferentially pre-swirling coming flow. Decreased pre-swirling intensity of the coming flow may effectively
restrain the flow separation and make the outflow from the crossover more uniform, which helps to improve the aerodynamic
performance of the successive de-swirling cascade. The flow inside the de-swirling cascade is a non-uniform swirling flow
with large separation. The complex secondary flow occurs along the main flow and experiences a process of generating, developing,
dissipating and collapsing.
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Translated from Power Engineering, 2007, 27(1): 24–28, 49 [译自: 动力工程] 相似文献
7.
This paper performs a numerical simulation of three-dimensional flow field in a centrifugal compressor with long inlet and outlet pipes using CFX software. By arranging virtual probes at different positions in both inlet and outlet planes, the aerodynamic performance of the centrifugal compressor is measured and compared with each other. Then effects of measuring positions on measurement results are discussed. The results show that it will generate notable measuring errors of the pressure ratio and efficiency if the inlet total pressure is measured using a single-point probe. The inlet total pressure data can be accurate when they are measured using a 3-point rake. The outlet total pressure and total temperature data can not be accurate if they are respectively measured at one circumferential position even using a multi-point rake. Increasing tangential measuring positions at the outlet is effective to improve the test accuracy. When the outlet total pressure and total temperature are respectively measured at 3 tangential positions, the data can be almost accurate. 相似文献
8.
Shaobin LI Jiexian SU Zhongqi WANG 《Frontiers of Energy and Power Engineering in China》2008,2(4):534-540
A redesign of a highly loaded fan stage by using high-turning bowed compressor stator was conducted. The original tandem stator
was replaced by the highly loaded bowed stator which was applicable to highly subsonic flow conditions. 3D contouring technique
and local modification of blade were applied to the design of the bowed blade in order to improve the aerodynamic performance
and the matching of the rotor and stator blade rows. Performance curves at different rotating speeds and performances at different
operating points for both the original fan stage and redesigned fan stage were obtained by numerical simulations. The results
show that the highly loaded bowed stator can be used not only to improve the structure and the aerodynamic performances at
various operating points of the compressor stage but also to provide high performances at off-design conditions. It is believed
that the highly loaded bowed stator can advance the design of high-performance compressor.
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Translated from Journal of Propulsion Technology, 2007, 28(1): 26–31 [译自: 推进技术] 相似文献
9.
《International Journal of Hydrogen Energy》2020,45(19):11276-11286
Centrifugal compressors are one of the most important auxiliary components in polymer electrolyte membrane fuel cell vehicles, which tend to operate at a narrow area with low specific speed. Here, the optimal design goals of centrifugal compressors are investigated on the basis of a lumped model for fuel cell systems. A three-dimensional multi-objective and multi-point aerodynamic optimization and data mining method for centrifugal compressors named ODM is presented via integrating a multi-island genetic algorithm, Reynolds-Average Navier-Stokes solver technique and self-organization map based data mining technique. Data mining indicates that compressor geometry would move to a small inlet diameter ratio and a narrow region of the outlet width ratio. Based on the optimization results, a centrifugal compressor for 100 kW fuel cell stack is manufactured. The experimental results show that the improvement of isentropic efficiency near low mass flow has been achieved, which indicates that the proposed ODM is effective in the performance improvement of centrifugal compressors for fuel cell vehicles. 相似文献
10.
The main objective of the present study is to experimentally investigate the effects of vapour quality and oil concentration on the performance of a swash plate compressor for automotive air conditioning systems. R‐134a is used as refrigerant. The compressor used is a typical automotive swash‐plate‐type compressor driven by a 10 hp variable‐speed electric motor and lubricated by polyalkylene glycol (PAG) oil. The variables measured during the experiment are pressure, temperature, oil concentration, total mass flow rate and vapour mass flow at the inlet and outlet of the compressor. The experiment was performed at varying compressor speeds, compression ratios and vapour quality. The results revealed some unknown aspects of the compression process in an automotive air conditioning system. The vapour quality does not affect volumetric efficiency, but influences isentropic efficiency of the compressor. In the vapour quality range of 80–90%, isentropic efficiency decreases with increasing vapour quality. During the compression process, only a portion of the liquid refrigerant evaporates. However, at the outlet of the compressor, refrigerant/oil mixture never reaches steady state. The evaporation ratio decreases with increasing compressor speed, and with increasing vapour quality as well. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
11.
Xinwei SHU Chuangang GU Jun XIAO Chuang GAO 《Frontiers of Energy and Power Engineering in China》2008,2(4):453-456
An optimization approach to centrifugal compressor blade design, incorporating uniform design method (UDM), computational
fluid dynamics (CFD) analysis technique, regression analysis method and genetic algorithms (GA), is presented. UDM is employed
to generate the geometric information of trial samples whose performance is evaluated by CFD technique. Then, function approximation
of sample information is performed by regression analysis method. Finally, global optimization of the approximative function
is obtained by genetic algorithms. Taking maximum isentropic efficiency as objective function, this optimization approach
has been applied to the optimum design of a certain centrifugal compressor blades. The results, compared with those of the
original one, show that isentropic efficiency of the optimized impeller has been improved which indicates the effectiveness
of the proposed optimization approach.
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Translated from Journal of Power Engineering, 2007, 27(5): 713–716 [译自: 动力工程] 相似文献
12.
Unsteady static pressure was measured and time-accurate numerical simulations were conducted in order to analyze unsteady behaviour of the centrifugal compressor diffuser. The unsteady static pressure was measured at the diffuser inlet and outlet at three different circumferential positions. Operation points near the surge, the design operation point and operation point near the choke were used in measurements. The time-accurate simulations were conducted at the design operation point and operation point near the choke. The whole compressor was modelled and the low Reynolds number k-εturbulence model was utilized in numerical simulations. The gathered numerical and experimental unsteady pressures were compared with each other. 相似文献
13.
14.
Renqiang Xiong Jacob N. Chung 《International Journal of Heat and Mass Transfer》2008,51(11-12):2914-2924
The characteristics of a pressure-driven water flow including flow micro-structures and pressure drops are investigated in serpentine micro-channels with miter bends. The micro-channels have rectangular cross-sections with hydraulic diameters of 0.209 mm, 0.412 mm and 0.622 mm, respectively. To segregate the bends and entrance effects individually from the total pressure drop, for each size three types of micro-channels: straight short, straight long and long serpentine, were fabricated to get the reliable pressure data without entrance effect. A micron-resolution particle image velocimetry system (micro-PIV) was develop and used to obtain the detailed velocity vector field. The experimental results show that the vortices around the outer and inner walls of the bend do not form when Re < 100. Those vortices appear and continue to develop with increasing Re number when Re is larger than a value around 100, and the shape and size of the vortices almost remain constant when the Re is larger than a value around 1000. The experimentally observed additional pressure drop due to the bend is commensurate with the strength of the calculated vortices. The bend loss coefficient Kb was observed to be related only with the Re number when Re < 100, but with the Re number and channel size when Re > 100. It almost keeps constant and changes in the range of ±10% when the Re is larger than a threshold value somewhere in 1000–1500. 相似文献
15.
16.
Vaned diffusers are widely used in centrifugal pumps, but little research has been published regarding action mechanism and the influence of diffuser vane height on dynamics performance of centrifugal pumps. Experimentally and numerically, the present investigation was focused on the dynamics performances of a low specific speed centrifugal pump equipped with vane diffusers with different vane heights. The pump performance was appraised when the diffuser vane height (h/b) was 0 (vaneless), 0.5, 0.6, 0.8 and 1 (vaned) times the diffuser width respectively. The pressure fields were numerically simulated in order to study the influence of half vane diffusers on inner flow field. The experimental results of operating performance showed that the efficiency was significantly improved for 2.5% at design flow point and the head was significantly improved for nearly 3 m at over flow point. The best efficiency point shifted towards higher flow rate with h/b reducing, and the high efficiency area was broadened by using half vane diffusers. Besides, half vane diffusers could reduce the intensity of pressure fluctuations at the leading edge of the stator vanes, and reduce the influence of rotor-stator interaction in tongue region. The numerical results showed that half vane diffusers could enhance flow uniformity in pumps, symmetry of pressure distributions on the impeller outlet and preferable regularity of radial force distributions. Therefore, it is very useful and feasible to apply half vane diffusers in centrifugal pumps. 相似文献
17.
18.
Jian JIANG Bo LIU Yangang WANG Xiangyi NAN 《Frontiers of Energy and Power Engineering in China》2008,2(3):320-325
Numerical simulation of three-dimensional turbulent flow in a multistage axial compressor blade row is conducted. A high resolution,
third-order ENN scheme is adopted to catch the shockwave and simulate the turbulent flow correctly, while an LU-SGS implicit
method is chosen to improve computation rate. A detailed and highly efficient numerical simulation system is thus constructed.
The investigation is focused on the grid connecting methods between the rotor and the stator and the corresponding treatment
of rotor-stator interactional surface. The final results of a three-stage axial compressor with inlet guide vanes conform
well to the experimental data.
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Translated from Chinese Journal of Applied Mechanics, 2007, 24(1): 21–25 [译自: 应用力学学报] 相似文献
19.
为了研究出口测量探针布局(探针数量及所处轴向位置)对压气机气动性能试验的影响,针对含测量探针的三级轴流压气机开展全周非定常数值计算。结果表明:出口测量探针将改变上游的流场结构,在末级叶片进出口截面对应探针的周向位置处形成局部高总压区和气流角偏移区,该区域覆盖有3~4个叶栅通道;随着探针与末级叶片轴向距离增加,高总压区的强度减弱,但作用范围增加;增加出口探针数量并未明显改善压气机试验性能评估精度,与无探针条件下的压气机性能相比,压比偏高0.6%,效率绝对值偏高1.8%;为减少试验中基于探针测点得到的压气机性能试验误差,不仅需考虑探针对测量截面流场的影响,更应根据测量截面流场不均匀性合理布局探针。 相似文献
20.
Among the six gen-IV reactor concepts recommended by the gen-IV international forum (GIF), supercritical water-cooled reactor
(SCWR), the only reactor with water as coolant, achieves a high thermal efficiency and, subsequently, has economic advantages
over the existing reactors due to its high outlet temperature. A thermal-hydraulic analysis of the SCWR assembly is performed
in this paper using the modified COBRA-IV code. Two approaches to reduce the hot channel factor are investigated: decreasing
the moderator mass flow and increasing the thermal resistance between moderator channel and its adjacent sub-channels. It
is shown that heat transfer deterioration cannot be avoided in SCWR fuel assembly. It is, therefore, highly required to calculate
the cladding temperature accurately and to preserve the fuel rod cladding integrity under heat transfer deterioration conditions.
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Translated from Nuclear Power Engineering, 2007, 28(5): 18–21, 58 [译自: 核动力工程] 相似文献