New Steps to Improve Rotordynamic Stability Predictions of Centrifugal Compressors

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Manoj K. Gupta ◽  
Thomas A. Soulas ◽  
Dara W. Childs
Keyword(s):  
Centrifugal Compressor ◽  
Flow Model ◽  
Aerodynamic Performance ◽  
Magnetic Bearing ◽  
Point Of View ◽  
Test Results ◽  
Performance Point ◽  
Pressure Test ◽  
Full Pressure ◽  
Rotor Model

Improved rotordynamic stability is desired by end users, and centrifugal compressor manufacturers are expected to meet, if not exceed, this expectation. Compressor manufacturers are required to design and build machines that are rotordynamically stable on the test stand and in the field. Confidence has been established in predicting the excitation forces from seals and bearings, but impeller aerodynamic excitation forces continue to be a challenge. While much attention is paid to impellers from an aerodynamic performance point of view, more efforts are needed from a rotordynamic standpoint. A high-pressure, reinjection centrifugal compressor is analyzed in order to predict rotordynamic stability using the best available resources for seals and bearings. Impeller shroud forces are predicted using the bulk-flow model developed by Gupta and Childs (Gupta, M., and Childs, D., Proc. of ASME Turbo Expo 2000, Power for Land, Sea, and Air). Each impeller stage is analyzed and an attempt is made to improve the estimation of impeller aerodynamic excitation forces. Logarithmic decrement (log dec) predictions for the full rotor model consisting of all the stages and seals are compared to the full-load full-pressure test measured values using a magnetic bearing exciter. A good correlation is obtained between the measured test results and analytical predictions.

New Steps to Improve Rotordynamic Stability Predictions of Centrifugal Compressors

2007 ◽  
Author(s):  
Manoj K. Gupta ◽  
Thomas A. Soulas ◽  
Dara W. Childs
Keyword(s):  
Centrifugal Compressor ◽  
Flow Model ◽  
Aerodynamic Performance ◽  
Magnetic Bearing ◽  
Point Of View ◽  
Test Results ◽  
Performance Point ◽  
Pressure Test ◽  
Full Pressure ◽  
Rotor Model

Improved rotordynamic stability is desired by end users, and centrifugal compressor manufacturers are expected to meet, if not exceed, this expectation. Compressor manufacturers are required to design and build machines that are rotordynamically stable on the test stand and in the field. Confidence has been established in predicting the excitation forces from seals and bearings, but impeller aerodynamic excitation forces continue to be a challenge. While much attention is paid to impellers from an aerodynamic performance point of view, more efforts are needed from a rotordynamic standpoint. A high-pressure, re-injection centrifugal compressor is analyzed in order to predict rotordynamic stability using the best available resources for seals and bearings. Impeller shroud forces are predicted using the bulk-flow model developed by Gupta and Childs [1]. Each impeller stage is analyzed and an attempt is made to improve the estimation of impeller aerodynamic excitation forces. Logarithmic decrement (log dec) predictions for the full rotor model consisting of all the stages and seals are compared to the full-load full-pressure test measured values using a magnetic bearing exciter. A good correlation is obtained between the measured test results and analytical predictions.

Stability of Centrifugal Compressors by Applications of Damper Seals

2011 ◽  
Author(s):  
Edmund A. Memmott
Keyword(s):  
Stability Analysis ◽  
Critical Frequency ◽  
Stable Operation ◽  
Test Results ◽  
Case Histories ◽  
Centrifugal Compressors ◽  
Full Load ◽  
Roughened Surface ◽  
Pressure Test ◽  
Full Pressure

This paper surveys the applications of damper seals to provide the stable operation with respect to rotordynamics of centrifugal compressors. Damper seals are applied as sealing devices at the division wall of back-to-back compressors and at the balance piston of in-line compressors. They consist of a roughened surface on the stator that is typically created by a pattern of holes. Rotordynamically stable operation is shown by a lack of or a small bounded amount of SSV (subsynchronous vibration) at the first fundamental lateral critical frequency. Experience plots showing the use of damper seals will be presented. Case histories of the use of damper seals will be given. Stability analysis and full load full pressure test results will be reviewed. The test results show no SSV at the first critical frequency with the damper seals.

Bolt Load Changes Due to Internal Pressure in Gasketed Flange Connections

2003 ◽  
Author(s):  
Satoshi Nagata ◽  
Mitsuhiro Matsumoto ◽  
Toshiyuki Sawa
Keyword(s):  
Internal Pressure ◽  
Thrust Force ◽  
High Reliability ◽  
Constant Load ◽  
Point Of View ◽  
Load Factor ◽  
Test Results ◽  
Performance Point ◽  
Load Factors ◽  
Sealing Performance

Bolt load changes due to internal pressure are very important in order to evaluate the integrity of gasketed flange connections in the sealing performance point of view, because its gasket stress which dominates leak rate changes according to the bolt load changes. For establishing a connection possesses high reliability and sufficient integrity, it is necessary to clarify the mechanics ofgasketed flange connections. For this purpose, authors carried out experimental pressurizing tests for 3B and 20B gasketed flange connections clamped by various bolt preloads and measured the bolt load changes with increasing internal pressure up to 5MPa. Also a load factor, which is defined as the ratio of axial bolt force increment to pressure thrust force, was calculated using the test results. The test results indicate that 3B and 20B flange connections with the spiral wound gaskets have a constant load factors under sufficient initial clamping forces in assemble.

Parametric Performance of a Class of Standard Discharge Scrolls for Industrial Centrifugal Compressors

2014 ◽  
Author(s):  
Marco Giachi ◽  
Vidyasagar Ramalingam ◽  
Elisabetta Belardini ◽  
Fabio De Bellis ◽  
Chanukya Reddy
Keyword(s):  
Centrifugal Compressor ◽  
Point Of View ◽  
Experimental Results ◽  
The Other ◽  
Delivery Time ◽  
Centrifugal Compressors ◽  
Performance Point ◽  
Engineering Solution ◽  
Other Hand

For many reasons, the discharge volute of a centrifugal compressor is becoming more and more critical for the performance of the machine. The most important are the need to reduce the size of the casing and to minimize the delivery time and cost of the compressor. A database of standard geometries represents a good engineering solution to both these requirements. In fact, it is possible, from a mechanical point of view, to design a class of similar volutes to fit different casings and stages. On the other hand, from the performance point of view, very little has been done to describe families of similar scrolls and how the performance of a baseline geometry can be adapted to take into account the differences which exist in the scrolls of the same family. A lot of data are available in literature but they refer to single specific geometries and to optimized individual designs. In this paper, a description of the analysis which has been done to investigate which may be the most convenient parameters to describe the volute performance is presented together with some experimental results which have been used to validate the analysis.

How to Design and Operate Quiet Centrifugal Compressor System

2000 ◽  
Author(s):  
Roman W. Motriuk
Keyword(s):  
Centrifugal Compressor ◽  
Dynamic Performance ◽  
Point Of View ◽  
Design Parameters ◽  
Clear Understanding ◽  
System Failures ◽  
Performance Point ◽  
Vibration Problems ◽  
And Performance ◽  
Fatigue Failures

Historically, designs of centrifugal compressor systems focused on the aerodynamic and performance aspects. Noise, pulsation, and vibration phenomena were rarely considered. Recent applications of high flow and high power centrifugal compressors require that this approach be changed. Several transmission system failures, in different gas transmission companies, were documented. They included fatigue failures of the compressor components, piping attachments, and, in some instances, pipework shell failures. As a result, numerous investigations were carried out. While the compressors were adequately designed from the aerodynamic performance point of view, they appeared to act as dynamic generators, producing excessive noise, pulsation, and vibration levels even when operated well within their design parameters. It was found that neither the designers nor equipment users had a clear understanding on how to practically analyse and mitigate such dynamic phenomena. The objective of this study is to briefly explain possible sources of the observed problems in the hope that such explanation might provide a means for preventing or minimising noise and pulsation generation in centrifugal machines. The study is based on the author’s experience in mitigating pulsation/noise and vibration problems mainly in the single stage natural gas centrifugal compressor systems. The study briefly describes differences in operation between vaned and vaneless diffuser compressors. It considers pipework and its influence on the compressor dynamic performance, and addresses some aspects of the compressor design in both aerodynamic and acoustic areas. Furthermore, it gives several practical methods to mitigate high frequency pulsation and vibration problems. Most of the approaches suggested here were implemented in the field and evaluated either by the author or others.

Centrifugal Compressor Performance Improvements Through Impeller Splitter Location

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
C. Xu ◽  
R. S. Amano
Keyword(s):  
Centrifugal Compressor ◽  
Aerodynamic Performance ◽  
Low Flow ◽  
Performance Tests ◽  
Test Results ◽  
Operational Cost ◽  
Vaneless Diffuser ◽  
Location Optimization ◽  
Performance Improvements ◽  
Compressor Performance

The splitter blades are very common to use for centrifugal compressor impellers to improve the compressor performance and manufacturing capability. In this study, a low-flow single-stage centrifugal compressor with a vaneless diffuser was used to investigate the location effects of the impeller splitter between two main blades. It is demonstrated that the splitter position provides an opportunity to improve the compressor performance and reduce the operational cost. The splitter location optimizations were performed numerically, and the optimal splitter location was identified. A prototype was built for the impeller with optimal splitter position. The performance tests were performed, and test results are compared with numerical analyses. The studies indicated that splitter positions have impacts on the compressor stage performances. The studies showed that the traditional splitter located in the middle of the two main blades is not the optimal location for aerodynamic performance. The splitter location optimization provided the opportunity to improve the centrifugal compressor performance further.

A Numerical Investigation on the Volute/Diffuser Interaction due to the Axial Distortion at Impeller Exit

2000 ◽  
Author(s):  
Fahua Gu ◽  
Abraham Engeda ◽  
Mike Cave ◽  
Jean-Luc Di Liberti
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Numerical Investigation ◽  
Steady Flow ◽  
Centrifugal Compressor ◽  
Vortex Structure ◽  
Flow Model ◽  
Single Stage ◽  
Mass Flows

Abstract A numerical simulation is performed on a single stage centrifugal compressor using the commercially available CFD software, CFX-TASCflow. The steady flow is obtained by circumferentially averaging the exit fluxes of the impeller. Three runs are made at design condition and off-design conditions. The predicted performance is in agreement with experimental data. The flow details inside the stationary components are investigated, resulting in a flow model describing the volute/diffuser interaction at design and off-design conditions. The recirculation and twin vortex structure are found to explain the volute loss increase at lower and higher mass flows, respectively.

The Potential of The Hotel Industry In Pandemic Era Based On Finance Performance Point Of View, Case Study: Indonesia

2021 ◽  
Vol 1 (1) ◽  
pp. 111-123
Author(s):  
Anton Effendi ◽  
◽  
Bambang Hadi Prabowo
Keyword(s):  
Hospitality Industry ◽  
Stock Exchange ◽  
Hotel Industry ◽  
Secondary Data ◽  
Reliable Data ◽  
Point Of View ◽  
Threshold Autoregressive ◽  
Performance Point ◽  
Occupancy Rates

This article aims to investigate and analyze the potential of the hospitality industry by comparing the potential occupancy rates and hotel revenues of foreign and domestic tourists. This investigation uses an investigation of company data obtained from reports from hotel companies throughout Indonesia which are listed on the Indonesia Stock Exchange and secondary data obtained from world banks and other reliable data. This study uses behavioral data analysis using Threshold Autoregressive from 2000 to 2019. It was found that domestic tourists are a new hope that needs to be considered in surviving and restoring the hospitality industry after being exposed to the COVID-19 pandemic which has led hotel companies. temporarily closed operations and part of the hotel went bankrupt. Optimization of domestic tourists allowed the hotel industry to develop rapidly after the Covid-19 pandemic ended.

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