scholarly journals Gazdynamic characteristics of the centrifugal compressor calculation

2018 ◽  
Vol 54 (4) ◽  
pp. 4-10
Author(s):  
M. Kalinkevych ◽  
V. Ihnatenko
Keyword(s):  
Experimental Data ◽  
Centrifugal Compressor ◽  
Dynamic Characteristics ◽  
Equations Of State ◽  
Element Analysis ◽  
Impeller Blade ◽  
Conservation Of Energy ◽  
Generalized Characteristics ◽  
Gas Dynamic ◽  
The Individual

Gas-dynamic characteristics of the compressor make it possible to evaluate its energy and economic properties, to predict the values of capacity, the generated gas pressure and the power consumption during the compressor operation. For more in-depth consideration of the compressor, it is desirable to have the characteristics of its individual stages. The element-by-element analysis of the characteristics of each stage makes it possible to improve the coordination of the operation of the individual elements with each other and thereby improve the gas-dynamic characteristics of the compressor. The loss factor and the static pressure recovery factor can be used as the values characterizing the properties of the individual elements of the stage. Coefficients are suitable for evaluating the energy properties of any element of the stage. To assess the effect of the element in question on the economy of the stage, it is necessary to establish what proportion of the work required for compression is the "loss" of energy in a given element, i.e. find the reduction in efficiency stage due to dissipation of energy into heat in this element. Calculation of performance of the centrifugal compressor is performed from the inlet to the outlet using the equations of state, of process, of continuity and conservation of energy. The initial data are geometric parameters of the compressor, the composition and the initial parameters of compressed gas, the rotational speed of the rotor. The basis of the elementwise calculation of gas-dynamic characteristics is the gas-dynamic characteristics of the stage elements. The calculation can be performed using the characteristics of the stage elements taken from the own bank of experimental data or using the generalized characteristics of the stage elements. To obtain generalized characteristics of the impeller, blade and no-blade diffusers, reverse guide vanes, experimental data were used, published in the works of Galerkin, Den, Rees, Seleznev and others, as well as experimental data obtained by the author. The generalized characteristics are obtained in the form of analytical dependences of the loss coefficients on the angles of attack or flow angles by approximation of experimental data. These dependences were used to analyze the gas-dynamic characteristics of a centrifugal compressor, which made it possible to develop recommendations for their improvement.

Geometric considerations in the capture of localized flow reversal in centrifugal compressor vaneless diffusers using steady state simulations

2016 ◽  
Vol 231 (21) ◽  
pp. 3959-3973
Author(s):  
Chris Clarke ◽  
Russell Marechale ◽  
Abraham Engeda ◽  
Michael Cave
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Centrifugal Compressor ◽  
Flow Characteristics ◽  
Rotating Stall ◽  
Flow Reversal ◽  
Contour Plot ◽  
Vaneless Diffuser ◽  
Impeller Blade ◽  
Steady State Simulation

A steady state simulation procedure is proposed to capture localized flow reversal inside of a centrifugal compressor vaneless diffuser. The procedure was performed on 12 compressor stages of varying geometry for speed lines of 13,100, 19,240, and 21,870 r/min. The simulations were run for all points from choke to surge including the experimentally determined rotating stall onset point. The experimental data and geometry were provided by Solar Turbines Inc. San Diego, CA. It was found possible to capture localized flow reversal inside of a vaneless diffuser using a steady state simulation. The results showed that using a geometric parameter, comparing the diffuser width, b4, to the impeller blade pitch distance, dpitch, it could be determined whether or not a steady state simulation could capture localized flow reversal. For values of b4/dpitch beneath 0.152 flow reversal could not be captured. But, for values of b4/dpitch above 0.177 localized flow reversal was captured. For values between 0.152 and 0.177, no conclusions could be drawn. Where possible, experimental data were compared against the diffuser inlet and outlet numerical profiles and the meridional contour plot. These comparisons served to validate the approach used in this article. These validations showed that the procedure defined herein is accurate and trustworthy within a specific range of geometric and flow characteristics. There are two other conclusions. First, the b4/dpitch parameter helps to define the type of flow breakdown. For b4/dpitch below 0.152, the flow breaks down in the circumferential direction, but for values of b4/dpitch above 0.177, the flow breaks down in the span-wise direction. Second, the simulations were able to capture instances of localized flow reversal before rotating stall onset. This concludes that localized flow reversal is not the determining factor in rotating stall onset as has been suggested by other investigators.

scholarly journals Evaluation of Joint Driving Torque and Finite Element Analysis in Articulate Robot through the simulation of Multi-Body Dynamics

2019 ◽  
Vol 8 (11) ◽  
pp. 682-686
Keyword(s):  
Experimental Data ◽  
Structural Analysis ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Simulation Software ◽  
Analysis Software ◽  
Characteristic Analysis ◽  
Element Analysis ◽  
Articulated Robots ◽  
Multi Body

Interest in high-speed articulated robots is increasing for product productivity expansion. High-speed articulated robots operate with rapid acceleration/deceleration moves, requiring dynamic characteristic analysis in the robot designing process. For this dynamic behavior analysis, simulation software is utilized, which supports product design verification and parts optimization. In analyzing the dynamic characteristics using the software, loading conditions can be obtained from experimental data or parts’ material characteristics. In a special case where data or experimental data on load conditions are hardly obtainable, multibody dynamics software is utilized. However, it is not easy to define an effective load and boundary conditions for systems with kinetically complicated connections. In order to solve such a problem, this present study investigated how to apply to structural analysis software the dynamic load found using dynamics and structural analysis software. In addition, the dynamic characteristics of high-speed articulated robots and robot link were assumed as a rigid body in implementing the dynamics analysis and structural analysis.

CFD-model of Vaneless Diffuser of Centrifugal Compressor

2021 ◽  
pp. 109-130
Author(s):  
О.А. Solovyeva ◽  
А.А. Drozdov ◽  
E.Yu. Popova ◽  
K.V. Soldatova
Keyword(s):  
Mathematical Model ◽  
Centrifugal Compressor ◽  
Dynamic Characteristics ◽  
Modeling Method ◽  
Relative Width ◽  
Vaneless Diffuser ◽  
Flow Angle ◽  
Flow Parameters ◽  
Gas Dynamic ◽  
Vaneless Diffusers

The centrifugal compressor design involves the use of approximate engineering techniques based on mathematical modeling. One of such techniques is the universal modeling method, which proves to be practically applicable. Having generalized a series of CFD calculations, we used a mathematical model in the latest version of the compressor model to calculate flow parameters in vaneless diffusers. The diffuser model was identified based on the results of experimental studies of average-flow model stages carried out at SPbPU. The model is also used to calculate Clark low-flow centrifugal compressor stages with narrow diffusers with a relative width in the range of 0.5--2.0 %. For these stages, the developed mathematical model showed insufficient efficiency, since the dimensions of the diffusers go beyond the limits of its applicability. To solve this problem, we calculated a series of vaneless diffusers with a relative width in the range of 0.6--1.2 % in the ANSYS CFX software package. Relying on the results of CFD calculations, we plotted the gas dynamic characteristics of the loss coefficients and changes in the flow angle depending on the flow angle at the inlet to the vaneless diffuser. To process the calculated data, the method of regression analysis was applied, with the help of which a system of algebraic equations was developed that connects geometric, gas-dynamic parameters and similarity criteria. The obtained equations are included in a new mathematical model of the universal modeling method for calculating the flow parameters of vaneless diffusers. Comparison of the calculated gas-dynamic characteristics according to the new model with experimental data showed the average error of modeling the calculated (maximum) efficiency equal to 1.08 %

DEVELOPMENT AND ANALYSIS OF NEW THEORETICAL MODELS OF GAS DYNAMIC PARAMETERS OF LOW-FREQUENCY PRESSURE PULSATIONS IN EXHAUST TRACTS

Akustika ◽  
2021 ◽  
pp. 61-64
Author(s):  
Anna Lubyanchenko ◽  
Aleksandr Shashurin ◽  
Nickolay Ivanov
Keyword(s):  
Equations Of State ◽  
Low Frequency ◽  
Theoretical Models ◽  
Combustion Products ◽  
Ideal Gas ◽  
Working Fluid ◽  
Dynamic Parameters ◽  
Conservation Of Energy ◽  
Gas Dynamic ◽  
Basic Equations

The exhaust tract with a silencer installed in it is represented by a design scheme consisting of a set of separate volumes connected to each other by holes or pipes. The following assumptions were made during the calculations: working fluid (combustion products), ideal gas, gas – dynamic parameters are averaged by volume, thermodynamic parameters are constant, the walls of the structure are rigid, the turbulent jet behind the exhaust tract is non-isothermal. The basic equations of the gas-dynamic mathematical model are used: the equation of conservation of matter, the equations of conservation of energy, the equations of state. After the transformations, dependences are obtained that allow us to determine the flow rate at the gas outlet of the dynamic path, pressure, and temperature in various sections of the path.

Properties of Refrigerants from Cubic Equations of State

2008 ◽  
Vol 59 (5) ◽  
Author(s):  
Viorel Feroiu ◽  
Dan Geana ◽  
Catinca Secuianu
Keyword(s):  
Experimental Data ◽  
Vapor Pressure ◽  
Equations Of State ◽  
Ternary Mixtures ◽  
Volumetric Properties ◽  
Mixing Rules ◽  
Saturation Curve ◽  
Equilibrium Thermodynamic ◽  
Liquid Equilibrium ◽  
Binary And Ternary Mixtures

Vapour � liquid equilibrium, thermodynamic and volumetric properties were predicted for three pure hydrofluorocarbons: difluoromethane (R32), pentafluoroethane (R125) and 1,1,1,2 � tetrafluoroethane (R134a) as well as for binary and ternary mixtures of these refrigerants. Three cubic equations of state GEOS3C, SRK (Soave � Redlich � Kwong) and PR (Peng � Robinson) were used. A wide comparison with literature experimental data was made. For the refrigerant mixtures, classical van der Waals mixing rules without interaction parameters were used. The GEOS3C equation, with three parameters estimated by matching several points on the saturation curve (vapor pressure and corresponding liquid volumes), compares favorably to other equations in literature, being simple enough for applications.

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