Comparison Study on Stage Performance of Centrifugal Compressors With Shrouded and Unshrouded Impellers

2021 ◽  
Author(s):  
Guang Xi ◽  
Chenxi Zhao ◽  
Yonghong Tang ◽  
Zhiheng Wang
Keyword(s):  
Tip Clearance ◽  
Design Parameters ◽  
Central Plane ◽  
Performance Potential ◽  
Peak Efficiency ◽  
Centrifugal Compressors ◽  
Blade Thickness ◽  
Meridional Profile ◽  
Design Speed

Abstract The shrouded and unshrouded impellers are two typical kinds of impellers, which are widely utilized in centrifugal compressors of various applications. Centrifugal compressors with unshrouded impellers are generally recognized to display inferior performance to the shrouded impellers with the same geometry. In this paper, a comparative experiment shows some results inconsistent with conventional cognition. Measured performance indicates that the peak efficiency of the centrifugal compressor with an unshrouded impeller is higher than the shrouded one, where the two impellers have the same geometry of meridional profile and blade central plane, and matched the same vaneless diffuser and volute. In order to explore the causes of this divergence, the effects of factors such as blade thickness, surface roughness of components, tip clearance and sealing leakage characteristics on performance are analyzed by CFD code. Numerical results show that reasonable reduction in the blade thickness and improvement on the surface quality of the impeller could effectively increase the peak efficiency and the choke mass flow rate of the shrouded impeller. The unshrouded impeller with arbitrary blade surfaces would be deformed under the action of centrifugal force to achieve a small tip clearance during operation, and then obtains higher efficiency at design speed. The research results are helpful to evaluate the performance potential and sensitive design parameters of shrouded and unshrouded impellers.

Influence of the Different Design Parameters to the Centrifugal Compressor Tip Clearance Loss

2011 ◽  
Author(s):  
Teemu Turunen-Saaresti ◽  
Ahti Jaatinen
Keyword(s):  
Centrifugal Compressor ◽  
Tip Clearance ◽  
Design Parameters ◽  
Clear Correlation ◽  
Compressor Stage ◽  
Centrifugal Compressors ◽  
Blade Number ◽  
Overall Performance ◽  
Specific Speed

In this paper the effect of the tip clearance was studied with six different centrifugal compressors and data available in literature. The changes in the overall performance of the compressor stage were examined. The aim was to study the influence of the different design parameters to the tip clearance loss. It was evident by the previous studies that the sensitivity of the centrifugal compressor to the tip clearance loss varies with different designs. However, for the designer it is important to know the effect of the tip clearance loss in order to initially evaluate the quality of different designs. Analysis of the data demonstrated that no clear correlation between the sensitivity of the tip clearance loss and the specific speed, the diffusion ratio, the blade number and the ratio of blade heights exists.

Influence of the Different Design Parameters to the Centrifugal Compressor Tip Clearance Loss

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Teemu Turunen-Saaresti ◽  
Ahti Jaatinen
Keyword(s):  
Centrifugal Compressor ◽  
Tip Clearance ◽  
Design Parameters ◽  
Clear Correlation ◽  
Compressor Stage ◽  
Centrifugal Compressors ◽  
Blade Number ◽  
Overall Performance ◽  
Specific Speed

In this paper the effect of the tip clearance was studied with six different centrifugal compressors and data available in literature. The changes in the overall performance of the compressor stage were examined. The aim was to study the influence of the different design parameters to the tip clearance loss. It was evident by the previous studies that the sensitivity of the centrifugal compressor to the tip clearance loss varies with different designs. However, for the designer it is important to know the effect of the tip clearance loss in order to initially evaluate the quality of different designs. Analysis of the data demonstrated that no clear correlation between the sensitivity of the tip clearance loss and the specific speed, the diffusion ratio, the blade number and the ratio of blade heights exists.

scholarly journals Experimental and Computational Investigation of the Tip Clearance Flow in a Transonic Axial Compressor Rotor

1996 ◽  
Vol 118 (2) ◽  
pp. 218-229 ◽  
Author(s):  
K. L. Suder ◽  
M. L. Celestina
Keyword(s):  
Axial Compressor ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Vortex Interaction ◽  
Peak Efficiency ◽  
Tip Clearance Flow ◽  
Compressor Rotor ◽  
Clearance Flow ◽  
Transonic Axial Compressor ◽  
Design Speed

Experimental and computational techniques are used to investigate tip clearance flows in a transonic axial compressor rotor at design and part-speed conditions. Laser anemometer data acquired in the endwall region are presented for operating conditions near peak efficiency and near stall at 100 percent design speed and at near peak efficiency at 60 percent design speed. The role of the passage shock/leakage vortex interaction in generating endwall blockage is discussed. As a result of the shock/vortex interaction at design speed, the radial influence of the tip clearance flow extends to 20 times the physical tip clearance height. At part speed, in the absence of the shock, the radial extent is only five times the tip clearance height. Both measurements and analysis indicate that under part-speed operating conditions a second vortex, which does not originate from the tip leakage flow, forms in the end-wall region within the blade passage and exits the passage near midpitch. Mixing of the leakage vortex with the primary flow downstream of the rotor at both design and part-speed conditions is also discussed.

scholarly journals Experimental and Computational Investigation of the Tip Clearance Flow in a Transonic Axial Compressor Rotor

1994 ◽  
Author(s):  
Kenneth L. Suder ◽  
Mark L. Celestina
Keyword(s):  
Axial Compressor ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Vortex Interaction ◽  
Peak Efficiency ◽  
Tip Clearance Flow ◽  
Compressor Rotor ◽  
Clearance Flow ◽  
Transonic Axial Compressor ◽  
Design Speed

Experimental and computational techniques are used to investigate tip clearance flows in a transonic axial compressor rotor at design and part speed conditions. Laser anemometer data acquired in the endwall region are presented for operating conditions near peak efficiency and near stall at 100% design speed and at near peak efficiency at 60% design speed. The role of the passage shock / leakage vortex interaction in generating endwall blockage is discussed. As a result of the shock / vortex interaction at design speed, the radial influence of the tip clearance flow extends to 20 times the physical tip clearance height. At part speed, in the absence of the shock, the radial extent is only 5 times the tip clearance height. Both measurements and analysis indicate that under part-speed operating conditions a second vortex, which does not originate from the tip leakage flow, forms in the endwall region within the blade passage and exits the passage near midpitch. Mixing of the leakage vortex with the primary flow downstream of the rotor at both design and part speed conditions is also discussed.

scholarly journals Maximizing the performance of pump inducers using CFD-based multi-objective optimization

2021 ◽  
Vol 65 (1) ◽  
Author(s):  
Trupen Parikh ◽  
Michael Mansour ◽  
Dominique Thévenin
Keyword(s):  
Flow Rate ◽  
Tip Clearance ◽  
Design Parameters ◽  
Multi Objective Optimization ◽  
Sweep Angle ◽  
Flow Rates ◽  
Blade Length ◽  
Multi Objective ◽  
Blade Thickness ◽  
Wide Range

AbstractPump inducers are usually employed within a limited flow rate range since the performance is known to drop out significantly far from their design point. Therefore, finding an optimal geometry that ensures efficient operation for a relatively wide range of flow rates is challenging. The present study tackles this problem using multi-objective optimization to identify optimal inducer configurations, delivering high performance for a wide flow range. 3D RANS single-phase turbulent simulations were performed using the $$k-\omega$$ k - ω turbulence model. The optimization was done by employing the Non-dominated Sorting Genetic Algorithm (NSGA-II) coupled with computational fluid dynamics (CFD). An established in-house flow optimization library (OPAL++) was used to automatically control the numerical simulations. The objective is to optimize the inducer geometrical parameters to simultaneously maximize the efficiency and pressure head curves, considering different flow rates, i.e., 80% (part-load), 100% (nominal), and 150% (overload) of the optimal flow rate for the considered pump. The optimization involves 8 most relevant design parameters, i.e., the axial blade length, blade sweep angle, blade pitch, hub taper angle, tip clearance gap, blade thickness at the hub, blade thickness at the tip, and the number of blades. A total of 5178 simulations over 37 generations have been needed to get a Pareto front containing 5 optimal configurations. This article discusses quantitatively the influence of each geometrical parameter on flow behavior and inducer performance. The results reveal in general that blade length, blade sweep angle, tip clearance gap, and blade thickness should be kept low for the considered application; inducers with high hub taper angles and 3 blades lead to optimal performance.

Radial Inflow Turbine Geometry Generation Method Using Third Order Bezier Curves for Blade Design

2019 ◽  
Author(s):  
U. Caldiño-Herrera ◽  
J. C. García ◽  
F. Sierra-Espinosa ◽  
J. O. Dávalos ◽  
M. A. Lira
Keyword(s):  
Flow Velocity ◽  
Angular Position ◽  
Flow Path ◽  
Design Parameters ◽  
Third Order ◽  
Bezier Curves ◽  
Bézier Curves ◽  
Blade Thickness ◽  
Meridional Profile ◽  
Relative Flow

Abstract Radial inflow turbines offer larger efficiency performance for small power applications due to its geometric configuration in which flow varies its radial position along the flow path. The geometry configuration of radial-inflow turbines demands a careful and adequate design of the flow path, since a 90° change of direction occurs from the radial inflow to the axial outflow. The blade camberline also requires attention since it defines the tangential flow direction along the meridional coordinate and any variation in its geometry affects the turbine performance. In this paper, a method for meridional profile and camberline geometry generation is proposed and tested through CFD. The method consists in using fourth order Bezier curves for defining the hub, shroud and mid-height blade meridional profile and third order Bezier curves for defining the relative flow velocity angle along the meridional coordinate, which leads to the camberline angular position in the rotor considering radial fibered blades. The blade thickness is set to vary linearly along the meridional coordinate and along the blade height. Different configurations of blade geometry are proposed and analyzed. These configurations are fixed to satisfy the design parameters. The code is programed in Python and adjusts the geometry data in files that are readable by meshing software. Thereby numerical calculations are performed to verify which configuration of camberline results in better performance. The calculations are done in models with the same boundary conditions and geometric data except for the variation of relative flow velocity angle along the meridional coordinate but setting the inlet and outlet angle to a fixed value. This way, the most suitable camberline geometry can be selected. The CDF model used for this analysis was validated with the experimental results reported by Kang et al. [1]

Parametric Design and Optimization of the Impeller Geometry for an Automotive Torque Converter Using DOE Method

2017 ◽  
Author(s):  
Guangqiang Wu ◽  
Jie Chen
Keyword(s):  
Parametric Design ◽  
Desirability Function ◽  
Torque Converter ◽  
Design Parameters ◽  
Exit Angle ◽  
Peak Efficiency ◽  
Impeller Blade ◽  
Design And Optimization ◽  
Blade Thickness ◽  
Impeller Geometry

Design of experiment (DOE) and computational fluid dynamics (CFD) techniques are applied to obtain an optimal design of the impeller geometry for an automotive torque converter. A new parametric geometric design method of impeller is proposed by means of parametric equations and Creo software. Eleven design parameters are used to obtain the parametric model and can be represented by six parameters including impeller blade number, blade thickness, bias angle, scroll angle, inlet angle and exit angle. DOE method is used to investigate the relative importance of the six design parameters for each response (stall torque ratio and peak efficiency). The impeller bias angle is found to exert the greatest influence on stall torque ratio while the impeller exit angle has the strongest impact on the peak efficiency. Three optimized cases for the impeller geometry of an automotive torque converter are obtained based on desirability function approach. The new parametric design and optimization methods can provide fundamental guidelines for performance enhancement in the design process of impeller geometry for an automotive torque converter.

DIAGNOSING QUALITY OF FRICTION SYSTEMS OF MECHANISMS OF DEVICES

2019 ◽  
Vol 1 (7) ◽  
pp. 10-13
Author(s):  
D. Yu. Ershov ◽  
I. N. Lukyanenko ◽  
E. E. Aman
Keyword(s):  
Surface Defects ◽  
Diagnostic Methods ◽  
Design Parameters ◽  
Diagnostic Model ◽  
Mechanical Assemblies ◽  
Local Defects ◽  
Relationship Of ◽  
The Relationship ◽  
Production And Operation

The article shows the need to develop diagnostic methods for monitoring the quality of lubrication systems, which makes it possible to study the dynamic processes of contacting elements of the friction systems of instrument mechanisms, taking into account roughness parameters, the presence of local surface defects of elements and the bearing capacity of a lubricant. In the present article, a modern diagnostic model has been developed to control the quality of the processes of production and operation of friction systems of instrument assemblies. With the help of the developed model, it becomes possible to establish the relationship of diagnostic and design parameters of the mechanical system, as well as the appearance of possible local defects and lubricant state, which characterize the quality of friction systems used in many mechanical assemblies of the mechanisms of devices. The research results are shown in the form of nomograms to assess the defects of the elements of friction mechanisms of the mechanisms of the devices.

Robust Compressor Blades for Desensitizing Operational Tip Clearance Variations

2014 ◽  
Author(s):  
Pranay Seshadri ◽  
Shahrokh Shahpar ◽  
Geoffrey T. Parks
Keyword(s):  
Robust Design ◽  
Total Pressure ◽  
Pressure Rise ◽  
Side Surface ◽  
Tip Clearance ◽  
Design Parameters ◽  
Compressor Blades ◽  
Robust Designs ◽  
Multi Objective ◽  
Mean And Variance

Robust design is a multi-objective optimization framework for obtaining designs that perform favorably under uncertainty. In this paper robust design is used to redesign a highly loaded, transonic rotor blade with a desensitized tip clearance. The tip gap is initially assumed to be uncertain from 0.5 to 0.85% span, and characterized by a beta distribution. This uncertainty is then fed to a multi-objective optimizer and iterated upon. For each iteration of the optimizer, 3D-RANS computations for two different tip gaps are carried out. Once the simulations are complete, stochastic collocation is used to generate mean and variance in efficiency values, which form the two optimization objectives. Two such robust design studies are carried out: one using 3D blade engineering design parameters (axial sweep, tangential lean, re-cambering and skew) and the other utilizing suction and pressure side surface perturbations (with bumps). A design is selected from each Pareto front. These designs are robust: they exhibit a greater mean efficiency and lower variance in efficiency compared to the datum blade. Both robust designs were also observed to have significantly higher aft and reduced fore tip loading. This resulted in a weaker clearance vortex, wall jet and double leakage flow, all of which lead to reduced mixed-out losses. Interestingly, the robust designs did not show an increase in total pressure at the tip. It is believed that this is due to a trade-off between fore-loading the tip and obtaining a favorable total pressure rise and higher mixed-out losses, or aft-loading the tip, obtaining a lower pressure rise and lower mixed-out losses.

Research on the Optimal Design Method of the Main Components for the Wheelchair Pickup

2013 ◽  
Vol 791-793 ◽  
pp. 799-802
Author(s):  
Ya Ping Wang ◽  
H.R. Shi ◽  
L. Gao ◽  
Z. Wang ◽  
X.Y. Jia ◽  
...  
Keyword(s):  
Parametric Design ◽  
Design Method ◽  
Basic Function ◽  
Design Parameters ◽  
Algorithm Optimization ◽  
Optimization Analysis ◽  
Research Designs ◽  
Optimal Design Method ◽  
Main Components

With the increasing of the aging of population all over the world, and With the inconvenience coming from diseases and damage, there will be more and more people using the wheelchair as a tool for transport. When it cant be short of the wheelchair in the daily life, the addition of the function will bring the elevation of the quality of life for the unfortunate. Staring with this purpose, the research designs a pickup with planetary bevel gear for the wheelchair. After determining the basic function of the wheelchair aids, the study determines the design parameters by using the knowledge of parametric design and completes the model for the system with Pro/E, on the other hand, it completes key components optimization analysis which is based on genetic algorithm optimization.

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