The geometric model of the multistage centrifugal compressor flow path in the ANSYS CFX

2019 ◽  
Author(s):  
A. A. Drozdov ◽  
V. I. Yaroshenko ◽  
Y. N. Pisarev
Keyword(s):  
Centrifugal Compressor ◽  
Geometric Model ◽  
Flow Path ◽  
Ansys Cfx ◽  
Multistage Centrifugal Compressor

scholarly journals The investigation of absolute flow non-uniform velocity distributions influence at the centrifugal compressor axial radial impeller inlet using numerical calculation methods in ANSYS CFX

2019 ◽  
Vol 140 ◽  
pp. 05008 ◽  
Author(s):  
L.A. Rakhmanina ◽  
A.V. Zuev ◽  
A. Yu. Petrov ◽  
A.A. Aksenov ◽  
Minh Hai Nguyen
Keyword(s):  
Numerical Calculation ◽  
Centrifugal Compressor ◽  
Average Diameter ◽  
Flow Path ◽  
Absolute Velocity ◽  
Calculation Methods ◽  
Software Environment ◽  
Ansys Cfx ◽  
Compressor Impeller ◽  
The Absolute

Currently, methods of numerical modelling are widely used. They are especially widely used in the design of turbo compressors. For the specific task of designing new flowing parts of a centrifugal compressor, it is not recommended to deviate from the canonical design techniques, but it is preferable to supplement them with numerical methods. This article is devoted to the end two-element stage investigation of a centrifugal compressor with an axial radial impeller; the stage main dimensions were obtained using the method of V.F. Rice. In order to obtain the necessary pressure characteristics and determine the dependence for the absolute velocity non-uniform distribution at the inlet to the axial radial impeller, the flow path main dimensions were optimized using numerical calculation methods. The calculation was performed using the SST turbulence model using computational gas dynamics methods in the ANSYS CFX software environment. Based on the optimization results, five compressor designs and corresponding characteristics were obtained. The absolute velocity distribution nature at the inlet to the centrifugal compressor axial radial impeller for five flow path variants is investigated. Empirical dependences are obtained for the deviation of the absolute velocity at the inlet in the hub section axial radial impeller and the absolute velocity deviation at the shroud from the absolute velocity at the average diameter based on the results of a numerical experiment. Recommendations are made for further absolute velocity distributions investigating at the inlet to the compressor impeller.

Analysis of Rotordynamic and Thermodynamic Performance of a Multistage Centrifugal Compressor Operating in the Minimum Flow Region

2018 ◽  
Author(s):  
Marco Giachi ◽  
Giuseppe Vannini ◽  
Pier Luigi Di Pillo
Keyword(s):  
Thermodynamic Analysis ◽  
Centrifugal Compressor ◽  
Stable Condition ◽  
Flow Region ◽  
Negative Slope ◽  
Design Practice ◽  
Thermodynamic Performance ◽  
Free Machine ◽  
Multistage Centrifugal Compressor ◽  
Day By Day

In this paper both rotordynamic and thermodynamic analysis of a multistage centrifugal compressor running with one or more stages in post-stall condition are presented. The purpose of this study is to demonstrate the machine can operate stable and safe in such condition (i.e. stable condition means the head vs. flow operating curve shall have negative slope and safe means a vibration free machine). This allows to extend the operating range at lower flow with respect to the current day-by-day design practice. Experimental results from ASME PTC10 Class 2 test carried out on a seven-stage compressor are shown to validate the analysis.

Multistage Centrifugal Compressor Surge Analysis: Part II—Numerical Simulation and Dynamic Control Parameters Evaluation

1999 ◽  
Vol 121 (2) ◽  
pp. 312-320 ◽  
Author(s):  
G. L. Arnulfi ◽  
P. Giannattasio ◽  
C. Giusto ◽  
A. F. Massardo ◽  
D. Micheli ◽  
...  
Keyword(s):  
Active Control ◽  
Centrifugal Compressor ◽  
Dynamic Control ◽  
Point Of View ◽  
Lumped Parameter Model ◽  
Theoretical Point ◽  
Control Parameters ◽  
Compression System ◽  
Compressor Surge ◽  
Multistage Centrifugal Compressor

This paper describes, from a theoretical point of view, the behavior of compression systems during surge and the effect of passive and active control devices on the instability limit of the system. A lumped parameter model is used to simulate the compression system described in Part I of this work (Arnulfi et al., 1999), based on an industrial multistage centrifugal compressor. A comparison with experimental results shows that the model is accurate enough to describe quantitatively all the features of the phenomenon. A movable wall control system is studied in order to suppress surge in the compressor. Passive and active control schemes are analyzed; they both address directly the dynamic behavior of the compression system to displace the surge line to lower flow rates. The influence of system, geometry and compressor speed is investigated: the optimum values of the control parameters and the corresponding increase in the extent of the stable operating range are presented in the paper.

scholarly journals Analysis of the velocity diagrams of impellers of centrifugal compressor stages after the preliminary design

2018 ◽  
Vol 245 ◽  
pp. 04004 ◽  
Author(s):  
Aleksandr Drozdov ◽  
Alexey Rekstin
Keyword(s):  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Flow Path ◽  
Preliminary Design ◽  
Flow Paths ◽  
Design Program ◽  
Three Stages ◽  
Correct Application ◽  
Development Laboratory

Preliminary design is an important stape in the development of centrifugal compressors and compressor stages. Basically for this purpose, various recommendations on the choice of the flow path dimensions are applied. Researchers of the Research and Development Laboratory “Gas dynamics of turbomachines” prof. Yu.B. Galerkin and A.F. Rekstin analyzed and summarized the dimensions of flow paths of 124 impellers. On the basis of this analysis, formulas were proposed for choosing the flow path dimensions of the centrifugal compressor stages, which were included in the preliminary design program. The formulas used are designed for relative Mach number of 0.7 and isentropic coefficient of 1.4. The correct application of these formulas for other Mach numbers and isentropic coefficient required development of an appropriate approach and algorithm for adjusting the height of the impeller blades at the outlet. Calculations of gas-dynamic characteristics using the Universal Modeling Method showed the need for selecting a coefficient that takes into account the influence of viscosity to obtain the required pressure characteristics of the compressor stage. This problem was also solved in the program of preliminary design. To check the quality of preliminary design, the results were verified using a non-viscous quasi-three-dimensional calculation program. Three stages were designed for parameters different to those used for development of preliminary design formulas. Analysis of the velocity diagrams of the impeller blades and distribution of meridional velocities showed good results of the preliminary design.

Flow Characteristics of a Novel Centrifugal Compressor Design

2016 ◽  
Author(s):  
Shashank Mishra ◽  
Shaaban Abdallah ◽  
Mark Turner
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Axial Compressor ◽  
Low Pressure ◽  
Flow Path ◽  
Optimization Techniques ◽  
Single Stage ◽  
Multi Stage ◽  
Compressor Design

Multistage axial compressor has an advantage of lower stage loading as compared to a single stage. Several stages with low pressure ratio are linked together which allows for multiplication of pressure to generate high pressure ratio in an axial compressor. Since each stage has low pressure ratio they operate at a higher efficiency and the efficiency of multi-stage axial compressor as a whole is very high. Although, single stage centrifugal compressor has higher pressure ratio compared with an axial compressor but multistage centrifugal compressors are not as efficient because the flow has to be turned from radial at outlet to axial at inlet for each stage. The present study explores the advantages of extending the axial compressor efficient flow path that consist of rotor stator stages to the centrifugal compressor stage. In this invention, two rotating rows of blades are mounted on the same impeller disk, separated by a stator blade row attached to the casing. A certain amount of turning can be achieved through a single stage centrifugal compressor before flow starts separating, thus dividing it into multiple stages would be advantageous as it would allow for more flow turning. Also the individual stage now operate with low pressure ratio and high efficiency resulting into an overall increase in pressure ratio and efficiency. The baseline is derived from the NASA low speed centrifugal compressor design which is a 55 degree backward swept impeller. Flow characteristics of the novel multistage design are compared with a single stage centrifugal compressor. The flow path of the baseline and multi-stage compressor are created using 3DBGB tool and DAKOTA is used to optimize the performance of baseline as well novel design. The optimization techniques used are Genetic algorithm followed by Numerical Gradient method. The optimization resulted into improvements in incidence and geometry which significantly improved the performance over baseline compressor design. The multistage compressor is more efficient with a higher pressure ratio compared with the base line design for the same work input and initial conditions.

Multistage Centrifugal Compressor Surge Analysis: Part I — Experimental Investigation

1998 ◽  
Author(s):  
G. L. Arnulfi ◽  
P. Giannattasio ◽  
C. Giusto ◽  
A. F. Massardo ◽  
D. Micheli ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Centrifugal Compressor ◽  
Reference Data ◽  
Dynamic Control ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Multi Stage ◽  
Compressor Surge ◽  
Multistage Centrifugal Compressor ◽  
Insight Into

This paper reports an experimental investigation on centrifugal compressor surge. The compression system consists of a four-stage blower with vaned diffusers and a large plenum discharging into the atmosphere through a throttle valve. Measurements of unsteady pressure and flow rate in the plant, and of instantaneous velocity in the diffusers of the first and fourth compressor stage are performed during deep surge, at several valve settings and three different rotation speeds. Additional tests have been carried out on a different system configuration, i.e., without plenum, in order to obtain the steady-state compressor characteristics and to collect reference data on stall in surge-free conditions. In this configuration, a fully developed rotating stall was detected in the compressor diffusers, while during surge it affects only a limited part of the surge cycle. The goal of the present experimental work was to get a deeper insight into unstable operating conditions of multi-stage centrifugal compressors and to validate a theoretical model of the system instability to be used for the design of dynamic control systems.

scholarly journals Performance Improvement of Return Channel in Multistage Centrifugal Compressor Using Multi-Objective Optimization

2012 ◽  
Author(s):  
Y. Nishida ◽  
H. Kobayashi ◽  
H. Nishida ◽  
K. Sugimura
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Coefficient ◽  
Swirl Flow ◽  
Optimized Design ◽  
Original Design ◽  
Flow Angle ◽  
Second Stage ◽  
Return Channel ◽  
Multistage Centrifugal Compressor ◽  
Stage Efficiency

The effect of the design parameters of a return channel on the performance of a multistage centrifugal compressor was numerically investigated, and the shape of the return channel was optimized using a multi-objective optimization method based on a genetic algorithm to improve the performance of the centrifugal compressor. The results of sensitivity analysis using Latin hypercube sampling suggested that the inlet-to-outlet area ratio of the return vane affected the pressure loss in the return channel, and that the inlet-to-outlet radius ratio of the return vane affected the outlet flow angle from the return vane. Moreover, this analysis suggested that the number of return vanes affected both the loss and the flow angle at the outlet. As a result of optimization, the number of return vanes was increased from 14 to 22 and the area ratio was decreased from 0.71 to 0.66. The radius ratio was also decreased from 2.1 to 2.0. Performance tests on a centrifugal compressor with two return channels (the original design and optimized design) were carried out using two-stage test apparatus. The measured flow distribution exhibited a swirl flow in the center region and a reversed swirl flow near the hub and shroud sides. The exit flow of the optimized design was more uniform than that of the original design. For the optimized design, the overall two-stage efficiency and pressure coefficient were increased by 0.7% and 1.5%, respectively. Moreover, the second-stage efficiency and pressure coefficient were respectively increased by 1.0% and 3.2%, It is considered that the increase in the second-stage efficiency was caused by the increased uniformity of the flow, and the rise in the pressure coefficient was caused by a decrease in the residual swirl flow. It was thus concluded from the numerical and experimental results that the optimized return channel improved the performance of the multistage centrifugal compressor.

On the Combined Effect on Operating Range of Adjustable IGVs and Variable Speed in Process Multistage Centrifugal Compressors

2013 ◽  
Author(s):  
Alberto Scotti Del Greco ◽  
Libero Tapinassi
Keyword(s):  
Centrifugal Compressor ◽  
Control Device ◽  
Variable Speed ◽  
Centrifugal Compressors ◽  
Speed Regulation ◽  
General Rules ◽  
Wide Range ◽  
Successful Control ◽  
Mach Numbers ◽  
Multistage Centrifugal Compressor

Adjustable inlet guide vanes (IGVs) and variable speed drivers are known as providing process compressors with an effective regulation all throughout the operating envelope of the machine. A large number of works exists in literature reporting the successful control of multistage centrifugal compressors by means of IGVs or speed separately, while a few studies document the combined use of both devices and their effect on compressor performance. The present paper details the off-design behavior of a multistage centrifugal compressor equipped with both types of control. It is shown that classical IGVs advantage in extending the operating envelope of a fixed speed multistage compressor tends to reduce when speed regulation is active too. In this sense, the average level of peripheral Mach numbers inside the compressor may be interpreted as a sort of threshold, since it deeply affects the stage mismatching at off-design conditions. This consideration is corroborated by a number of applications in a wide range of design peripheral Mach numbers. Based on those cases, the paper reviews the general effectiveness of the combined regulation, thus outlining some general rules of thumb for the choice of the optimal control device for a multistage centrifugal compressor.

scholarly journals The influence of flow passage geometry on the performances of a supercritical CO2 centrifugal compressor

2018 ◽  
Vol 22 (Suppl. 2) ◽  
pp. 409-418 ◽  
Author(s):  
Dong-Bo Shi ◽  
Yu-Qi Wang ◽  
Yong-Hui Xie ◽  
Di Zhang
Keyword(s):  
Centrifugal Compressor ◽  
Supercritical Co2 ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Thermal Design ◽  
Original Design ◽  
Impeller Blade ◽  
Flow Passage ◽  
Ansys Cfx ◽  
Design Idea

In this paper, based on the thermodynamic design of the supercritical carbon dioxide (sCO2) centrifugal compressor, the design idea of the flow passage geometries and the method to improve the performance of the sCO2 centrifugal compressor are discussed. With the help of commercial software ANSYS CFX, the influence of the shape of the leading edge and trailing edge is studied, and the elliptical leading edge makes the pressure ratio 10.30% higher and the efficiency 3.95% higher than the square leading edge. By changing the forward-swept angle and backward-swept angle of the leading edge, the effects of aerodynamic swept shape in sCO2 centrifugal compressor are discussed. The effect of the gap between the impeller blade and diffuser blade is discussed, and the 10 mm gap makes the performance best. The pressure ratio is increased by 2.5% compared with the original design, while at the same time the efficiency is slightly improved. In summary, based on thermal design of the sCO2 centrifugal compressor, the effects of different flow geometries are analyzed in detail.

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