Performance Degradation due to Fouling and Recovery After Washing in a Multistage Test Compressor

2020 ◽  
Author(s):  
Nicola Casari ◽  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
Alessio Suman ◽  
Alessandro Vulpio
Keyword(s):  
Characteristic Curve ◽  
Pressure Ratio ◽  
Performance Curve ◽  
Internal Surfaces ◽  
Gradual Loss ◽  
Before And After ◽  
Stator Vane ◽  
Compressor Performance ◽  
Multistage Test ◽  
Dust Ingestion

Abstract Land-based power units have to fulfill even more high levels of production and reliability. In harsh environments (desert and tropical installations, typically), the power unit ingests high amounts of dust that might deposit inside the compressor. In this paper, the analysis of a multistage compressor performance that operates under sandy and humid conditions has been assessed. The compressor units, that equips the Allison 250 C18 compressor, has been subjected to multiple runs under severe conditions of soil dust ingestion. The compressor has been operated according to subsequent runs and at the end of each run, the performance curve was recorded and the performance losses, in terms of pressure ratio, have been measured during the operations. The characteristic curve of each run is representative of the level of contamination of the unit. Finally, the compressor has been washed and the performance curve, in the recovered conditions, has been recorded. The results show the modification and the downward shift of the characteristic curves which lead to a gradual loss of the compressor performance. The curves realized after dust ingestion have been compared with the recovered curve after online washing. The measurement shows a promising recovery of the performances, even if, the compressor flow path appears affected by localized deposits able to resist to the droplet removal action. Detailed photographic reports of the IGV and the first compressor stages have been included in this analysis. After each run, the IGV, the rotor blade and stator vane of the first stage and the hub and the shroud surfaces have been photographed. The pictures show the deposition patterns on the blades and the compressor surfaces. The comparison of the pictures of the internal surfaces, before and after the washing, highlights the parts that are more critical to clean and needy of attention during offline washing and overhaul.

Performance Degradation Due to Fouling and Recovery After Washing in a Multistage Test Compressor

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Nicola Casari ◽  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
Alessio Suman ◽  
Alessandro Vulpio
Keyword(s):  
Guide Vane ◽  
Characteristic Curve ◽  
Pressure Ratio ◽  
Inlet Guide Vane ◽  
Performance Curve ◽  
Internal Surfaces ◽  
Before And After ◽  
Stator Vane ◽  
Compressor Performance ◽  
Dust Ingestion

Abstract Land-based power units have to fulfill even more high levels of production and reliability. In harsh environments (desert and tropical installations, typically), the power unit ingests high amounts of dust that might deposit inside the compressor. In this paper, the analysis of a multistage compressor performance that operates under sandy and humid conditions has been assessed. The compressor units, which equips the Allison 250 C18 compressor, has been subjected to multiple runs under severe conditions of soil dust ingestion. The compressor has been operated according to subsequent runs, and at the end of each run, the performance curve was recorded; the performance losses, in terms of pressure ratio, have been measured during the operations. The characteristic curve of each run is representative of the level of contamination of the unit. Finally, the compressor has been washed, and the performance curve, in the recovered conditions, has been recorded. The results show the modification and the downward shift of the characteristic curves which lead to a gradual loss of the compressor performance. The curves realized after dust ingestion have been compared with the recovered curve after online washing. The measurement shows a promising recovery of the performances, even if the compressor flow path appears affected by localized deposits able to resist to the droplet removal action. Detailed photographic reports of the inlet guide vane (IGV) and the first compressor stages have been included in this analysis. After each run, the IGV, the rotor blade and stator vane of the first stage, and the hub and the shroud surfaces have been photographed. The pictures show the deposition patterns on the blades and the compressor surfaces. The comparison of the pictures of the internal surfaces, before and after the washing, highlights the parts that are more critical to clean and needy of attention during offline washing and overhaul.

Application of a Computer Vision Tool for Automated Glottic Tracking to Vocal Fold Paralysis Patients

2021 ◽  
pp. 019459982198960
Author(s):  
Tiffany V. Wang ◽  
Nat Adamian ◽  
Phillip C. Song ◽  
Ramon A. Franco ◽  
Molly N. Huston ◽  
...  
Keyword(s):  
Vocal Fold ◽  
Assessment Tool ◽  
Medical Center ◽  
Characteristic Curve ◽  
Academic Medical Center ◽  
Vocal Fold Paralysis ◽  
Control Group ◽  
Large Patient ◽  
Patient Reported ◽  
Before And After

Objectives (1) Demonstrate true vocal fold (TVF) tracking software (AGATI [Automated Glottic Action Tracking by artificial Intelligence]) as a quantitative assessment of unilateral vocal fold paralysis (UVFP) in a large patient cohort. (2) Correlate patient-reported metrics with AGATI measurements of TVF anterior glottic angles, before and after procedural intervention. Study Design Retrospective cohort study. Setting Academic medical center. Methods AGATI was used to analyze videolaryngoscopy from healthy adults (n = 72) and patients with UVFP (n = 70). Minimum, 3rd percentile, 97th percentile, and maximum anterior glottic angles (AGAs) were computed for each patient. In patients with UVFP, patient-reported outcomes (Voice Handicap Index 10, Dyspnea Index, and Eating Assessment Tool 10) were assessed, before and after procedural intervention (injection or medialization laryngoplasty). A receiver operating characteristic curve for the logistic fit of paralysis vs control group was used to determine AGA cutoff values for defining UVFP. Results Mean (SD) 3rd percentile AGA (in degrees) was 2.67 (3.21) in control and 5.64 (5.42) in patients with UVFP ( P < .001); mean (SD) 97th percentile AGA was 57.08 (11.14) in control and 42.59 (12.37) in patients with UVFP ( P < .001). For patients with UVFP who underwent procedural intervention, the mean 97th percentile AGA decreased by 5 degrees from pre- to postprocedure ( P = .026). The difference between the 97th and 3rd percentile AGA predicted UVFP with 77% sensitivity and 92% specificity ( P < .0001). There was no correlation between AGA measurements and patient-reported outcome scores. Conclusions AGATI demonstrated a difference in AGA measurements between paralysis and control patients. AGATI can predict UVFP with 77% sensitivity and 92% specificity.

scholarly journals Influence of Seal Cavity Leakage Flow on Compressor Performance Investigated with a Circumferentially Averaged Method

2021 ◽  
Vol 11 (2) ◽  
pp. 780
Author(s):  
Dong Liang ◽  
Xingmin Gui ◽  
Donghai Jin
Keyword(s):  
Flow Field ◽  
Pressure Ratio ◽  
Interaction Mechanism ◽  
Main Flow ◽  
Leakage Flow ◽  
Destructive Effect ◽  
Through Flow ◽  
Compressor Performance ◽  
Overall Performance ◽  
Flow Blockage

In order to investigate the effect of seal cavity leakage flow on a compressor’s performance and the interaction mechanism between the leakage flow and the main flow, a one-stage compressor with a cavity under the shrouded stator was numerically simulated using an inhouse circumferentially averaged through flow program. The leakage flow from the shrouded stator cavity was calculated simultaneously with main flow in an integrated manner. The results indicate that the seal cavity leakage flow has a significant impact on the overall performance of the compressor. For a leakage of 0.2% of incoming flow, the decrease in the total pressure ratio was 2% and the reduction of efficiency was 1.9 points. Spanwise distribution of the flow field variables of the shrouded stator shows that the leakage flow leads to an increased flow blockage near the hub, resulting in drop of stator performance, as well as a certain destructive effect on the flow field of the main passage.

scholarly journals Simulation of Compressor Performance Deterioration due to Erosion

1989 ◽  
Author(s):  
W. Tabakoff ◽  
A. N. Lakshminarasimha ◽  
M. Pasin
Keyword(s):  
Fault Model ◽  
Experimental Results ◽  
Performance Tests ◽  
Individual Stage ◽  
One Stage ◽  
Before And After ◽  
Performance Deterioration ◽  
Compressor Performance ◽  
Multistage Compressor ◽  
The Individual

Experimental results obtained from cascades and one stage compressor performance tests before and after erosion were used to test a fault model to represent erosion. This model was implemented on a stage stacking program developed to demonstrate the effect of erosion in a multistage compressor. The effect of the individual stage erosion on the overall compressor performance is also demonstrated.

Effect of Different Geometrical Inlet Pipes on a High Speed Centrifugal Compressor

2013 ◽  
Author(s):  
Ce Yang ◽  
Ben Zhao ◽  
C. C. Ma ◽  
Dazhong Lao ◽  
Mi Zhou
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Ratio ◽  
Inlet Pipe ◽  
Unsteady Pressure ◽  
Bent Pipe ◽  
Low Mass ◽  
Compressor Performance ◽  
Spectral Frequency ◽  
The One

Two different inlet configurations, including a straight pipe and a bent pipe, were experimentally tested and numerically simulated using a high-speed, low-mass flow centrifugal compressor. The pressure ratios of the compressor with the two inlet configurations were tested and then compared to illustrate the effect of the bent inlet pipe on the compressor. Furthermore, different circumferential positions of the bent inlet pipe relative to the volute are discussed for two purposes. One purpose is to describe the changes in the compressor performance that result from altering the circumferential position of the bent inlet pipe relative to the volute. This change in performance may be the so-called clocking effect, and its mechanism is different from the one in multistage turbomachinery. The other purpose is to investigate the unsteady flow for different matching states of the bent inlet pipe and volute. Thus, the frequency spectrum of unsteady pressure fluctuation was applied to analyze the aerodynamic response. Compared with the straight inlet pipe, the experimental results show that the pressure ratio is modulated and that the choke point is shifted in the bent inlet pipe. Similarly, the pressure ratio can be influenced by altering the circumferential position of the bent inlet pipe relative to the volute, which may have an effect on the unsteady pressure in the rotor section. Therefore, the magnitude of interest spectral frequency is significantly changed by clocking the bent inlet pipe.

Numerical Analysis of Deposits and Corrosion Influence on a Centrifugal Compressor Performance

2012 ◽  
Author(s):  
Mohammad R. Aligoodarz ◽  
Mohammad Reza Soleimani Tehrani ◽  
Hadi Karrabi ◽  
Mohammad R. Roshani
Keyword(s):  
Numerical Modeling ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Mechanical Damage ◽  
3D Numerical Modeling ◽  
Compressor Blades ◽  
Turbine Performance ◽  
Common Causes ◽  
Sst Turbulence Model ◽  
Compressor Performance

Turbo machineries including compressors performance degrades over the period of operation and deviates from design levels due to causes including dust entrance into the compressor, blades mechanical damage, erosion and corrosion. These lead to reduction in compressor performance, efficiency and pressure ratio. Subsequently gas turbine performance is affected since their operation sate is correlated. In this study the numerical investigation of common causes that determine geometric characteristics of a 2-stage centrifugal compressor running in a gas station, including blades fouling and corrosion is performed. 3D Numerical modeling is implemented along with utilization of Shear Stress Transport (SST) turbulence model and independency from the grids is verified.

1995 ASME Gas Turbine Award Paper: Development and Application of a Multistage Navier–Stokes Solver: Part I—Multistage Modeling Using Bodyforces and Deterministic Stresses

1998 ◽  
Vol 120 (2) ◽  
pp. 205-214 ◽  
Author(s):  
C. M. Rhie ◽  
A. J. Gleixner ◽  
D. A. Spear ◽  
C. J. Fischberg ◽  
R. M. Zacharias
Keyword(s):  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Design Procedure ◽  
Potential Interaction ◽  
Theoretical Development ◽  
Navier Stokes ◽  
Radial Profiles ◽  
Compressor Performance ◽  
High Level

A multistage compressor performance analysis method based on the three-dimensional Reynolds-averaged Navier-Stokes equations is presented in this paper. This method is an average passage approach where deterministic stresses are used to ensure continuous physical properties across interface planes. The average unsteady effects due to neighboring blades and/or vanes are approximated using deterministic stresses along with the application of bodyforces. Bodyforces are used to account for the “potential” interaction between closely coupled (staged) rows. Deterministic stresses account for the “average” wake blockage and mixing effects both axially and radially. The attempt here is to implement an approximate technique for incorporating periodic unsteady flow physics that provides for a robust multistage design procedure incorporating reasonable computational efficiency. The present paper gives the theoretical development of the stress/bodyforce models incorporated in the code, and demonstrates the usefulness of these models in practical compressor applications. Compressor performance prediction capability is then established through a rigorous code/model validation effort using the power of networked workstations. The numerical results are compared with experimental data in terms of one-dimensional performance parameters such as total pressure ratio and circumferentially averaged radial profiles deemed critical to compressor design. This methodology allows the designer to design from hub to tip with a high level of confidence in the procedure.

scholarly journals Prediction of Arteriovenous Fistula Clinical Maturation from Postoperative Ultrasound Measurements: Findings from the Hemodialysis Fistula Maturation Study

2018 ◽  
Vol 29 (11) ◽  
pp. 2735-2744 ◽  
Author(s):  
Michelle L. Robbin ◽  
Tom Greene ◽  
Michael Allon ◽  
Laura M. Dember ◽  
Peter B. Imrey ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arteriovenous Fistula ◽  
Characteristic Curve ◽  
Ultrasound Measurement ◽  
Case Mix ◽  
Elimination Algorithm ◽  
Clinical Center ◽  
Ultrasound Measurements ◽  
Before And After ◽  
Ultrasound Parameters

BackgroundThe utility of early postoperative ultrasound measurements in predicting arteriovenous fistula (AVF) clinical maturation is uncertain.MethodsWe investigated the relationships of ultrasound parameters with AVF clinical maturation in newly created AVF, measured at 1 day and 2 and 6 weeks, in 602 participants of a multicenter, observational cohort study. A backward elimination algorithm identified ultrasound measurements that independently predicted unassisted and overall AVF maturation. Candidate variables included AVF blood flow, diameter, and depth, upper arm arterial diameter, presence of stenosis, presence of accessory veins, seven case-mix factors (age, sex, black race, AVF location, diabetes, dialysis status, and body mass index), and clinical center. We evaluated the accuracy of the resulting models for clinical prediction.ResultsAt each ultrasound measurement time, AVF blood flow, diameter, and depth each predicted in a statistically significant manner both unassisted and overall clinical maturation. Moreover, neither the remaining ultrasound parameters nor case-mix factors were associated with clinical AVF maturation after accounting for blood flow, diameter, and depth, although maturation probabilities differed among clinical centers before and after accounting for these parameters. The crossvalidated area under the receiver operating characteristic curve for models constructed using these three ultrasound parameters was 0.69, 0.74, and 0.79 at 1 day and 2 and 6 weeks, respectively, for unassisted AVF clinical maturation and 0.69, 0.71, and 0.76, respectively, for overall AVF maturation.ConclusionsAVF blood flow, diameter, and depth moderately predicted unassisted and overall AVF clinical maturation. The other factors considered did not further improve AVF maturation prediction.

scholarly journals Numerical and experimental analyses of intake silencer and its effects on turbocharger compressor performance

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401982667 ◽  
Author(s):  
Chen Liu ◽  
Yipeng Cao ◽  
Yang Liu ◽  
Wenping Zhang ◽  
Pingjian Ming ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Transmission Loss ◽  
Pressure Ratio ◽  
Pressure Fluctuations ◽  
Noise Spectrum ◽  
Acoustic Mode ◽  
Frequency Noise ◽  
Reduced Pressure ◽  
Compressor Rotor ◽  
Compressor Performance

Numerical studies of a marine diesel engine intake silencer are conducted to evaluate its performance, and effects of the silencer on the turbocharger compressor performance are also discussed. The results show that the duct acoustic mode method can be used in the silencer transmission loss prediction, and the predicted noise reduction and main frequency range agree with the measurements fairly well. However, it is found that the silencer compromises the compressor performance by shortening its operating range. It is found that the static pressure on the compressor blade surface is decreased, thus the compressor total-to-total pressure ratio and isentropic efficiency are reduced. Pressure fluctuations at compressor rotor and stator inlets enhanced when a silencer is installed, which means the trend of pressure spectrum in the rotor and stator passage is changed. Compared with the results of a compressor in natural aspiration, it is found that the silencer can significantly reduce high-frequency noise. In particular, it is quite effective in tonal noise reduction. In addition, the compressor inlet noise spectrum indicates that noise radiation characteristics are different with a silencer installed.

Effects of water ingestion on the tip clearance flow in compressor rotors

2018 ◽  
Vol 233 (11) ◽  
pp. 4235-4246 ◽  
Author(s):  
Lu Yang ◽  
Hai Zhang ◽  
Aqiang Lin
Keyword(s):  
Pressure Ratio ◽  
External Disturbance ◽  
Droplet Breakup ◽  
Tip Clearance ◽  
Suction Surface ◽  
Two Phase ◽  
Tip Clearance Flow ◽  
Water Ingestion ◽  
Clearance Flow ◽  
Compressor Performance

The tip region of compressor rotors may be filled with water when aircraft is flying in heavy rain environment. In order to explore the effects of water ingestion on the compressor performance and the characteristics of tip clearance flow, the Euler–Lagrange method has been utilized to simulate the two-phase flow inside a transonic rotor (NASA rotor 35). The typical trajectory of water droplet in compressor has been introduced firstly to simply understand the situation of water ingestion and to verify the reliability of some special droplet breakup models. The simulation results show that water droplets will change the distribution of airflow parameters along the span direction, which leads to the decrease of mass flow rate and the increase of attack angle at the tip region, as well as the separation of boundary layer on the suction surface. Furthermore, the momentum losses caused by droplet impingement and breakup directly causes a sharp increase in the static entropy at the blade tip region. On the other hand, the ingestion of droplet brings an external disturbance to airflow, and although it has some dissipated effects on the turbulence kinetic energy, it aggravates the unsteady characteristics of turbulent flow seriously at the tip region. Finally, by comparing the compressor performance under wet and dry states, it can be concluded that the pressure ratio and adiabatic efficiency of compressor decrease after water ingestion, and the compression efficiency drops by 1–2% on the whole while the operating point moves forward and the stable working boundary becomes narrow.

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