Improvement of the Performance of a Centrifugal Compressor by Modifying the Volute Inlet

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Semi Kim ◽  
Junyoung Park ◽  
Kukyoung Ahn ◽  
Jehyun Baek
Keyword(s):  
Radial Velocity ◽  
Mass Flow ◽  
Flow Characteristics ◽  
Total Efficiency ◽  
Swirl Velocity ◽  
Mass Flow Rates ◽  
New Type ◽  
Comparison Of The Results ◽  
Simulated Flow ◽  
Better Than

In centrifugal compressors, the diffuser and the volute have strong influences on the flow discharged from the impeller and thus also on the performance. In particular, a key parameter is the radial velocity at the volute inlet; it determines the swirl velocity, which is dissipated as a loss, i.e., it results in performance degradation. With the aim of reducing the swirl loss, a new type of volute with a modified inlet height was tested in this study. The volute inlet height was modified to 6 mm and 7 mm from the original height of 5 mm. The reliability of our computations was tested by comparison of the results of a model with this original height with experimental data. Flow analyses were conducted not only at the design mass flow rate but also at lower and higher mass flow rates. A higher total-to-total efficiency was obtained as a result of the linear increases of the volute inlet height from the diffuser outlet to 6 mm and 7 mm. Our detailed investigation of the simulated flow fields shows that the flow characteristics for a volute inlet height of 6 mm are better than those for a volute inlet height of 5 mm. These results clearly show that a greater volute inlet height assists in pressure recovery and reduces swirl loss in the volute. However, the volute inlet height of 7 mm results in larger hub separation and more energy loss, and thus in inferior performance. Therefore, the hub separation and the radial velocity at the volute inlet strongly influence the performance.

scholarly journals Determination of mass flow characteristics of supersonic axisymmetric nozzle diaphragms in modeling variable duties of low-consumption turbines

2020 ◽  
pp. 39-43
Author(s):  
Р.Р. Симашов ◽  
С.В. Чехранов
Keyword(s):  
Mass Flow ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Relative Length ◽  
Axisymmetric Nozzle ◽  
Relative Flow Rate ◽  
Wide Range ◽  
Mass Flow Rates ◽  
Subsonic Part ◽  
Low Consumption

В работе приводятся обобщающие зависимости коэффициентов расхода сопловых аппаратов со сверхзвуковыми осесимметричными соплами в широком диапазоне изменения определяющих геометрических и режимных параметров. Предложена двухпараметрическая функция, учитывающая влияние расположения сопел в сопловом аппарате и степени конфузорности дозвуковой части осесимметричного сопла на коэффициент расхода. Показано слабое влияние на коэффициент расхода относительного радиуса закругления стенки в узкой части сопла и относительной длины дозвуковой части сопла в области их оптимальных значений определенных по минимуму потерь кинетической энергии. Переменные режимы работы сопла учитываются зависимостью относительного коэффициента расхода в функции от числа Рейнольдса в критическом сечении сопла. Полученные в работе эмпирические зависимости позволяют использовать их при моделировании переменных режимов и многорежимной оптимизации малорасходных турбин. The research presents generalizing dependences of mass flow rates in supersonic axisymmetric nozzle diaphragms n a wide range of variation of the governing geometric and operating parameters. A two-parameter function is proposed that takes into account the influence of the location of the nozzles in the nozzle apparatus and the degree of compression of the flow of the subsonic part of the nozzle on the mass flow rate. It is shown that the relative radius of rounding of the nozzle wall in the vicinity of the throat section and the relative length of the subsonic part of the nozzle in the region of their optimal values determined by the minimum of kinetic energy losses have a weak effect on the flow rate. Variable duties of nozzle operation are taken into account by the dependence of the relative flow rate as a function of the Reynolds number in the throat of the nozzle. The empirical dependencies obtained in this work make it possible to use them in modeling variable modes and multi-mode optimization of low-consumption turbines.

An Experimental Study of the Flow of R-407C in an Adiabatic Spiral Capillary Tube

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
M. K. Mittal ◽  
R. Kumar ◽  
A. Gupta
Keyword(s):  
Experimental Data ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Capillary Tube ◽  
Flow Characteristics ◽  
Flow Rates ◽  
Tube Test ◽  
Mass Flow Rates ◽  
R 134A

The objective of this study is to investigate the effect of coiling on the flow characteristics of R-407C in an adiabatic spiral capillary tube. The characteristic coiling parameter for a spiral capillary tube is the coil pitch; hence, the effect of the coil pitch on the mass flow rate of R-407C was studied on several capillary tube test sections. It was observed that the coiling of the capillary tube significantly reduced the mass flow rate of R-407C in the adiabatic spiral capillary tube. In order to quantify the effect of coiling, the experiments were also conducted for straight a capillary tube, and it was observed that the coiling of the capillary tube reduced the mass flow rate in the spiral tube in the range of 9–18% as compared with that in the straight capillary tube. A generalized nondimensional correlation for the prediction of the mass flow rates of various refrigerants was developed for the straight capillary tube on the basis of the experimental data of R-407C of the present study, and the data of R-134a, R-22, and R-410A measured by other researchers. Additionally, a refrigerant-specific correlation for the spiral capillary was also proposed on the basis of the experimental data of R-407C of the present study.

An Experimental Study of a “Once-Through” Thermosiphon System

1988 ◽  
Vol 110 (2) ◽  
pp. 90-97 ◽  
Author(s):  
R. Celentano ◽  
R. Kirchner
Keyword(s):  
Experimental Study ◽  
Mass Flow ◽  
Natural Circulation ◽  
Time Dependent ◽  
Circulation System ◽  
Outlet Temperature ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
New Type ◽  
Mass Flows

An experimental study was conducted on the operation of a “once-through” thermosiphon system. This new type of natural circulation system, unlike the standard thermosiphon system, heats the collector fluid in one pass without any recirculation. An electrically heated manifold was used to simulate the useful solar gain. Power was varied with time in 22 half-hour increments to simulate the actual daily useful solar gain. The time-dependent responses of the system in terms of temperatures and mass flow rates were recorded and plotted. The response time for mass flow and temperature to approach steady state varied directly with the size of the power step. Two experiments were conducted; one which tracked mass flows and outlet temperatures for variable useful solar gains, and a second which tracked mass flows at constant outlet temperature for variable useful solar gains.

Performance Characteristics of a Centrifugal Compressor with Air Injection

1973 ◽  
Vol 187 (1) ◽  
pp. 425-434 ◽  
Author(s):  
J. D. Ledger ◽  
R. S. Benson ◽  
H. Furukawa
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Total Mass ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Performance Characteristics ◽  
Air Injection ◽  
Delivery Pressure ◽  
Mass Flow Rates ◽  
The Right

The parameters which influence the performance characteristics of centrifugal compressors with air injection through nozzles at the rotor tip are developed using both dimensional analysis and a simple model. Experiments on a small centrifugal compressor show that the injection air pressure is the main influence on the overall performance such as excess torque, increased delivery pressure and increased delivery flow. With air injection the pressure-mass flow characteristics are displaced to the right with surge occurring at increased total mass flow rates and the overall pressure ratio across the compressor is increased for the same total mass flow.

A Comparison of a Mono, Twin and Double Scroll Turbine for Automotive Applications

2015 ◽  
Author(s):  
Jason Walkingshaw ◽  
Georgios Iosifidis ◽  
Tobias Scheuermann ◽  
Dietmar Filsinger ◽  
Nobuyuki Ikeya
Keyword(s):  
Mass Flow ◽  
Flow Characteristics ◽  
High Mass ◽  
Flow Rates ◽  
Engine Simulation ◽  
Engine Model ◽  
Trade Offs ◽  
Mass Flow Rates ◽  
The Individual ◽  
The Impact

As a means of meeting ever increasing emissions and fuel economy demands car manufacturers are using aggressive engine downsizing. To maintain the power output of the engine turbocharging is typically used. Due to the miss-match of the mass flow characteristics of the engine to the turbocharger, at low engine mass flow rates, the turbocharger can suffer from slow response known as “Turbolag”. Mono-scroll turbines are capable of providing good performance at high mass flow rates and in conjunction with low inertia mixed flow turbines can offer some benefits for transient engine response. With a multi-entry system the individual volute sizing can be matched to the single mass flow pulse from the engine cylinders. The exhaust pulse energy can be better utilised by the turbocharger turbine improving turbocharger response, while the interaction of the engine exhaust pulses can be better avoided, improving the scavenging of the engine. The behaviour of a mono-scroll turbocharger with the engine using engine simulation tools has been well established. What requires further investigation is the comparison with multi-entry turbines. CFD (Computational Fluid Dynamics) has been used to examine the single admission behaviour of a twin and double scroll turbine. Turbocharger gas stand maps of the multi-entry turbines have been measured at full and single admission. This data has been used in a 0D engine model. In addition, the turbine stage has been tested on the engine and a validation of the engine model against the engine test data is presented. Using the validated engine model a comparison has been made to understand the differences in the sizing requirements of the turbine and the interaction of the mono-scroll and multi-entry turbines with the engine. The impact of the different efficiency and mass flow rate trends of the mono and multi-entry turbochargers are discussed and the trade-offs between the design configurations regarding on engine behaviour are investigated.

Influence of secondary air mass flow rates on gas/particle flow characteristics near the swirl burner region

Energy ◽  
2011 ◽  
Vol 36 (5) ◽  
pp. 3599-3605 ◽  
Author(s):  
Jianping Jing ◽  
Zhengqi Li ◽  
Lin Wang ◽  
Lizhe Chen ◽  
Guohua Yang
Keyword(s):  
Mass Flow ◽  
Flow Characteristics ◽  
Particle Flow ◽  
Swirl Burner ◽  
Flow Rates ◽  
Air Mass ◽  
Mass Flow Rates ◽  
Secondary Air

Performance Characteristics of a Centrifugal Compressor with Air Injection

1973 ◽  
Vol 187 (1) ◽  
pp. 425-434 ◽  
Author(s):  
J. D. Ledger ◽  
R. S. Benson ◽  
H. Furukawa
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Total Mass ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Performance Characteristics ◽  
Air Injection ◽  
Delivery Pressure ◽  
Mass Flow Rates ◽  
The Right

The parameters which influence the performance characteristics of centrifugal compressors with air injection through nozzles at the rotor tip are developed using both dimensional analysis and a simple model. Experiments on a small centrifugal compressor show that the injection air pressure is the main influence on the overall performance such as excess torque, increased delivery pressure and increased delivery flow. With air injection the pressure-mass flow characteristics are displaced to the right with surge occurring at increased total mass flow rates and the overall pressure ratio across the compressor is increased for the same total mass flow.

Flow Analysis and Assessment of Loss Models in the Symmetric Volute of a Turbo-Blower

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Semi Kim ◽  
Junyoung Park ◽  
Bumseok Choi ◽  
Jehyun Baek
Keyword(s):  
Cfd Simulation ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Cfd Simulations ◽  
Turbo Blower ◽  
Mass Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
Loss Coefficients ◽  
Simulated Flow

The objectives of the present study were to investigate the flow structure and assess the accuracy of loss correlations in the symmetric volute of a turbo-blower using 3D steady flow analysis methods. To accurately model the flow field in the volute, an impeller with a single blade, a diffuser with 13 vanes, and a volute were used as the calculation domains for the computational fluid dynamics (CFD) simulations. Numerical results were validated by comparison with experimental results for the performance of a turbo-blower operated under three operating conditions: high (0.38 kg/s), normal (0.3 kg/s), and low (0.23 kg/s) mass flow rates. The accuracy of the loss correlation sets reported in four previous studies was compared with the CFD simulation predictions. These comparisons showed that the correlation sets did not accurately represent the total pressure loss in the symmetric volute of a turbo-blower, and a modified correlation set that included adjustments for the loss coefficients was proposed. Detailed investigations of the simulated flow fields were compared to understand the flow characteristics in the volute under the designed operating conditions.

A Comparison of a Mono-, Twin-, and Double-Scroll Turbine for Automotive Applications

2015 ◽  
Vol 138 (5) ◽  
Author(s):  
Jason Walkingshaw ◽  
Georgios Iosifidis ◽  
Tobias Scheuermann ◽  
Dietmar Filsinger ◽  
Nobuyuki Ikeya
Keyword(s):  
Mass Flow ◽  
Flow Characteristics ◽  
Engine Exhaust ◽  
Simulation Tools ◽  
Engine Simulation ◽  
Engine Model ◽  
Mass Flow Rates ◽  
Single Mass ◽  
The Individual ◽  
The Impact

As a means of meeting ever increasing emissions and fuel economy demands, car manufacturers are using aggressive engine downsizing. To maintain the power output of the engine, turbocharging is typically used. Due to the mismatch of the mass flow characteristics of the engine to the turbocharger, at low engine mass flow rates (MFRs), the turbocharger can suffer from slow response known as “Turbolag.” Mono-scroll turbines are capable of providing good performance at high MFRs and in conjunction with low inertia mixed flow turbines can offer some benefits for transient engine response. With a multi-entry system, the individual volute sizing can be matched to the single mass flow pulse from the engine cylinders. The exhaust pulse energy can be better utilized by the turbocharger turbine improving turbocharger response, while the interaction of the engine exhaust pulses can be better avoided, improving the scavenging of the engine. The behavior of a mono-scroll turbocharger with the engine using engine simulation tools has been well established. What requires further investigation is the comparison with multi-entry turbines. Computational fluid dynamics (CFD) has been used to examine the single-admission behavior of a twin- and double-scroll turbine. Turbocharger gas stand maps of the multi-entry turbines have been measured at full and single admissions. This data have been used in a 0D engine model. In addition, the turbine stage has been tested on the engine, and a validation of the engine model against the engine test data is presented. Using the validated engine model, a comparison has been made to understand the differences in the sizing requirements of the turbine and the interaction of the mono-scroll and multi-entry turbines with the engine. The impact of the different efficiency and MFR trends of the mono and multi-entry turbochargers is discussed, and the tradeoffs between the design configurations regarding on-engine behavior are investigated.

Numerical study on flow characteristics of rotor pumps including cavitation

2014 ◽  
Vol 229 (14) ◽  
pp. 2626-2638 ◽  
Author(s):  
Yingyuan Liu ◽  
Leqin Wang ◽  
Zuchao Zhu
Keyword(s):  
Numerical Model ◽  
Mass Flow ◽  
Volume Fraction ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Two Dimensional ◽  
Flow Rates ◽  
Factors Affecting ◽  
Remarkable Effect ◽  
Mass Flow Rates

This work is purposed to study the flow characteristics of rotor pumps including cavitation. First, a simplified two-dimensional numerical model is developed and computing strategies of the numerical analysis for cavitation are set up, including the selection of cavitation model and its parameters. Second, the reliability and accuracy of the two-dimensional numerical model are verified by experimental results. Then, several factors affecting the cavitation are discussed, including the rotational speeds, pressure differences, clearance sizes, and inlet pressures. For different rotational speeds and pressure differences, the mass flow rates with cavitation are a little larger than that without cavitation, but the amplitudes of the mass flow rates with cavitation are much larger than that without cavitation. Meanwhile, the volume fraction of the water vapor increases with the increasing speeds and the decreasing pressure differences. However, compared with the influence of rotational speeds, the influence of the pressure differences on the vapor contents is relatively smaller. Regarding the clearance size, the smaller the clearance size is, the stronger the cavitation will be. Furthermore, the clearance size between two rotors has a larger effect on the cavitation than that between rotor and pump case. For inlet pressure, it has a little effect on the mass flow rates when cavitation is not considered, but it presents a remarkable effect for the model with cavitation. In addition, the peaks of the volume fractions of vapor and the mass flow rates generally offset backward with the decreasing inlet pressures.

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