Effects of isentropic efficiency of turbomachinery components on entropy production for small turbojet engine

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hakan Aygün
Keyword(s):  
Phase I ◽  
Entropy Production ◽  
Phase Ii ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Content Type ◽  
Turbojet Engine ◽  
Design Variables ◽  
Level Zero ◽  
Isentropic Efficiency

Purpose Usage of gas turbine engines has increased by day due to rising demand for military and civil applications. This case results in investigating diverse topics related to energy efficiency and irreversibility of these systems. The purpose of this paper is to perform a detailed entropy assessment of turbojet engines for different flight conditions. Design/methodology/approach In this study, for small turbojet engines used in unmanned aerial vehicles, parametric cycle analysis is carried out at (sea level-zero Mach (hereinafter phase-I)) and (altitude of 9,000 m- Mach of 0.7 (hereinafter phase-II)). Based on this analysis, variation of performance and thermodynamic parameters with respect to change in isentropic efficiency of the compressor (CIE) and turbine (TIE) is examined at both phases. In this context, the examined ranges for CIE is between 0.78 and 0.88 whereas TIE is between 0.85 and 0.95. Findings Increasing isentropic efficiency decreases entropy production of the small turbojet engine. Moreover, the highest entropy production occurs in the combustor in the comparison of other components. Namely, it decreases from 2.81 to 2.69 kW/K at phase-I and decreases from 1.44 to 1.39 kW/K at phase-II owing to rising CIE. Practical implications It is thought that this study helps in understanding the relationship between entropy production and the efficiency of components. Namely, the approach used in the current analysis could help decision-makers or designers to determine the optimum value of design variables. Originality/value Due to rising isentropic efficiencies of both components, it is observed that specific fuel consumption (SFC) decreases whereas specific thrust (ST) increases. Also, the isentropic efficiency of a compressor affects relatively SFC and ST higher than that of the turbine.

Computational investigation of foreign object damage sustained by environmental barrier coatings (EBCs) and SiC/SiC ceramic-matrix composites (CMCs)

2015 ◽  
Vol 11 (2) ◽  
pp. 238-272 ◽  
Author(s):  
Mica Grujicic ◽  
Jennifer Snipes ◽  
Ramin Yavari ◽  
S. Ramaswami ◽  
Rohan Galgalikar
Keyword(s):  
Gas Turbine ◽  
Ceramic Matrix ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Foreign Object ◽  
Barrier Coatings ◽  
Content Type ◽  
Environmental Barrier Coatings ◽  
Foreign Object Damage ◽  
Environmental Barrier

Purpose – The purpose of this paper is to prevent their recession caused through chemical reaction with high-temperature water vapor, SiC-fiber/SiC-matrix ceramic-matrix composite (CMC) components used in gas-turbine engines are commonly protected with so-called environmental barrier coatings (EBCs). EBCs typically consist of three layers: a top thermal and mechanical protection coat; an intermediate layer which provides environmental protection; and a bond coat which assures good EBC/CMC adhesion. The materials used in different layers and their thicknesses are selected in such a way that the coating performance is optimized for the gas-turbine component in question. Design/methodology/approach – Gas-turbine engines, while in service, often tend to ingest various foreign objects of different sizes. Such objects, entrained within the gas flow, can be accelerated to velocities as high as 600 m/s and, on impact, cause substantial damage to the EBC and SiC/SiC CMC substrate, compromising the component integrity and service life. The problem of foreign object damage (FOD) is addressed in the present work computationally using a series of transient non-linear dynamics finite-element analyses. Before such analyses could be conducted, a major effort had to be invested toward developing, parameterizing and validating the constitutive models for all attendant materials. Findings – The computed FOD results are compared with their experimental counterparts in order to validate the numerical methodology employed. Originality/value – To the authors’ knowledge, the present work is the first reported study dealing with the computational analysis of the FOD sustained by CMCs protected with EBCs.

Robust approaches for monitoring logistic regression profiles under outliers

2017 ◽  
Vol 34 (4) ◽  
pp. 494-507 ◽  
Author(s):  
Ahmad Hakimi ◽  
Amirhossein Amiri ◽  
Reza Kamranrad
Keyword(s):  
Logistic Regression ◽  
Robust Control ◽  
Phase I ◽  
Control Chart ◽  
Phase Ii ◽  
Control Charts ◽  
Likelihood Estimation ◽  
Estimation Of Parameters ◽  
Content Type ◽  
Practical Applications

Purpose The purpose of this paper is to develop some robust approaches to estimate the logistic regression profile parameters in order to decrease the effects of outliers on the performance of T2 control chart. In addition, the performance of the non-robust and the proposed robust control charts is evaluated in Phase II. Design/methodology/approach In this paper some, robust approaches including weighted maximum likelihood estimation, redescending M-estimator and a combination of these two approaches (WRM) are used to decrease the effects of outliers on estimating the logistic regression parameters as well as the performance of the T2 control chart. Findings The results of the simulation studies in both Phases I and II show the better performance of the proposed robust control charts rather than the non-robust control chart for estimating the logistic regression profile parameters and monitoring the logistic regression profiles. Practical implications In many practical applications, there are outliers in processes which may affect the estimation of parameters in Phase I and as a result of deteriorate the statistical performance of control charts in Phase II. The methods developed in this paper are effective for decreasing the effect of outliers in both Phases I and II. Originality/value This paper considers monitoring the logistic regression profile in Phase I under the presence of outliers. Also, three robust approaches are developed to decrease the effects of outliers on the parameter estimation and monitoring the logistic regression profiles in both Phases I and II.

scholarly journals The Advanced Low-Emissions Catalytic-Combustor Program: Phase I — Description and Status

1979 ◽  
Author(s):  
A. J. Szaniszlo
Keyword(s):  
Phase I ◽  
Gas Turbine ◽  
Primary Objective ◽  
Pollutant Emission ◽  
Turbine Engines ◽  
Variable Geometry ◽  
Gas Turbine Engines ◽  
Analytical Evaluation ◽  
Three Phase ◽  
Catalytic Combustor

The Advanced Low-Emissions Catalytic-Combustor Program ia an ongoing three-phase contract contract effort with the primary objective of evolving the technology required for incorporating catalytic combustors into advanced aircraft gas-turbine engines. Phase I is corrently in progress. At the present time, analytical evaluation is being conducted on advanced catalytic combustor concepts — including variable geometry — with their known inherent potential advantages of low level pollutant emission, widened combustion at ability limits, and reduced pattern factor for longer turbine life. Phases II and III will consist of experimental evaluation of the most promising concepts.

scholarly journals Pathophysiology of the Rhesus Macaque Model for Inhalational Brucellosis

2011 ◽  
Vol 80 (1) ◽  
pp. 298-310 ◽  
Author(s):  
Lisa N. Henning ◽  
Stephen M. Miller ◽  
Dennis H. Pak ◽  
Amber Lindsay ◽  
David A. Fisher ◽  
...  
Keyword(s):  
Phase I ◽  
Rhesus Macaque ◽  
Phase Ii ◽  
Brucella Melitensis ◽  
Human Brucellosis ◽  
Content Type ◽  
Macaque Model ◽  
Reactive Protein ◽  
Two Phases ◽  
Aerosol Infection

ABSTRACTThe objective of this study was to characterize the rhesus macaque (RM) as a model for inhalational brucellosis in support of the U.S. Food and Drug Administration's (FDA) Animal Rule. The pathophysiology of chronicBrucella melitensisaerosol infection was monitored in two phases that each occurred over an 8-week time period; dose escalation (8 RMs; targeted doses of 5.0E+03, 5.0E+04, or 5.0E+05 CFU/animal or the unchallenged control) and natural history (12 RMs; targeted dose of 2.50E+05 CFU/animal or the unchallenged control). RMs given an aerosol challenge withB. melitensisdeveloped undulating fevers (6/6 phase I; 8/9 phase II), positive enriched blood cultures (5/10; phase II), and bacterial burdens in tissues starting 14 to 21 days postchallenge (6/6 phase I; 10/10 phase II). In addition, 80% (8/10; phase II) of infected RMs seroconverted 14 to 21 days postchallenge. RMs developed elevations in certain liver enzymes and had an increased inflammatory response by 3 weeks postchallenge as shown by increases in C-reactive protein (6/8) and neopterin (4/8), which correlated with the onset of a fever. As early as 14 days postchallenge, positive liver biopsy specimens were detected (2/8), and ultrasound imaging showed the development of splenomegaly. Finally, histopathologic examination found lesions attributed toBrucellainfection in the liver, kidney, lung, and/or spleen of all animals. The disease progression observed with the RMs in this study is analogous to human brucellosis pathophysiology. Thus, the results from this study support the use of the RM as an animal model for inhalational brucellosis to evaluate the efficacy of novel vaccines and therapeutics againstB. melitensis.

Lowest emission sustainable aviation biofuels as the potential replacement for the Jet-A fuels

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Anderson A. ◽  
Karthikeyan A. ◽  
Ramesh Kumar C. ◽  
Ramachandran S. ◽  
Praveenkumar T.R.
Keyword(s):  
Gas Turbine ◽  
Fossil Fuels ◽  
Gas Turbine Engine ◽  
Turbine Engines ◽  
Emission Characteristics ◽  
Gas Turbine Engines ◽  
Content Type ◽  
Turbine Engine ◽  
Micro Gas Turbine ◽  
Fuel Blends

Purpose The purpose of this study is to predict the performance and emission characteristics of micro gas turbine engines powered by alternate fuels. The micro gas turbine engine performance, combustion and emission characteristics are analyzed for the jet fuel with different additives. Design/methodology/approach The experimental investigation was carried out with Jet A-1 fuel on the gas turbine engines at different load conditions. The primary blends of the Jet A-1 fuels are from canola and solid waste pyrolysis oil. Then the ultrasonication of highly concentrated multiwall carbon nanotubes is carried with the primary blends of canola (Jet-A fuel 70%, canola 20% and 10% ethanol) and P20E (Jet-A 70% fuel, 20% PO and 10% ethanol). Findings The consumption of the fuel is appreciable with the blends at a very high static thrust. The 39% reduction in thrust specific fuel consumption associated with a 32% enhance in static thrust with P20E blend among different fuel blends. Moreover, due to the increase in ethanol concentration in the blends PO20E and C20E lead to a 22% rise in thermal efficiency and a 9% increase in higher oxygen content is observed. Practical implications The gas turbine engine emits very low emission of gases such as CO, CO2 and NOx by using the fuel blends, which typically reduces the fossil fuel usage limits with reduced pollutants. Originality/value The emission of the gas turbine engines is further optimized with the addition of hydrogen in Jet-A fuel. That is leading to high specific fuel exergy and owing to the lower carbon content in the hydrogen fuel when compared with that of the fossil fuels used in gas turbine engines. Therefore, the usage of hydrogen with nanofluids was so promising based on the results obtained for replacing fossil fuels.

scholarly journals Turbojet Engine Industrial Min–Max Controller Performance Improvement Using Fuzzy Norms

Electronics ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 314 ◽  
Author(s):  
Soheil Jafari ◽  
Theoklis Nikolaidis
Keyword(s):  
Response Time ◽  
Gas Turbine ◽  
Control Strategy ◽  
Turbine Engines ◽  
Selection Strategy ◽  
Gas Turbine Engines ◽  
Control Loops ◽  
Turbojet Engine ◽  
Transient Control ◽  
The Impact

The Min–Max control strategy is the most widely used control algorithm for gas turbine engines. This strategy uses minimum and maximum mathematical functions to select the winner of different transient engine control loops at any instantaneous time. This paper examines the potential of using fuzzy T and S norms in Min–Max selection strategy to improve the performance of the controller and the gas turbine engine dynamic behavior. For this purpose, different union and intersection fuzzy norms are used in control strategy instead of using minimum and maximum functions to investigate the impact of this idea in gas turbine engines controller design and optimization. A turbojet engine with an industrial Min–Max control strategy including steady-state and transient control loops is selected as the case study. Different T and S norms including standard, bounded, Einstein, algebraic, and Hamacher norms are considered to be used in control strategy to select the best transient control loop for the engine. Performance indices are defined as pilot command tracking as well as the engine response time. The simulation results confirm that using Einstein and Hamacher norms in the Min–Max selection strategy could enhance the tracking capability and the response time to the pilot command respectively. The limitations of the proposed method are also discussed and potential solutions for dealing with these challenges are proposed. The methodological approach presented in this research could be considered for enhancement of control systems in different types of gas turbine engines from practical point of view.

Wellness 101: health education for the university student

2010 ◽  
Vol 110 (4) ◽  
pp. 309-327 ◽  
Author(s):  
S. Joan Wharf Higgins ◽  
Lara L. Lauzon ◽  
Ann C. Yew ◽  
Christopher D. Bratseth ◽  
Nicole McLeod
Keyword(s):  
Health Education ◽  
Phase I ◽  
Phase Ii ◽  
Holistic Health ◽  
First Year ◽  
Education Curriculum ◽  
Content Type ◽  
Campus Environment ◽  
Two Phases ◽  
The Impact

PurposeThis paper aims to describe two phases of a mixed‐method study: in phase I, the wellness practices of students at a Canadian university are reported. These data informed the re‐development of a first‐year health education course. Subsequent to its revision, phase II of the study assessed the impact of the course on students' wellness practices and learnings.Design/methodology/approachIn phase I, 855 students completed a survey rating ten wellness practices relating to themselves. Survey results were explored further in focus groups with 60 students. In phase II, a pre‐ and post‐design assessed the impact of the health education curriculum. Wellness practices were surveyed, at the beginning and end of term, and content analysis was conducted on students' assignments.FindingsIn phase I, the mean overall wellness score was 779.7 out of 1,000 or “good”. Students scored highest in sexuality and safety, and lowest in physical activity and nutrition. Qualitative analyses revealed four primary themes important to students' wellness: being or holistic health; belonging or feeling connected to others and the campus; becoming or studying to achieve a professional or scholarly degree; and balance – or the search for stability. In phase II, significant changes were found for seven wellness scores when comparing the beginning and end of semester. Analysis of course assignments found that students left the course with enhanced affect and knowledge levels.Originality/valueThe results support the argument that a health education curriculum, responsive to students' identified needs, and in conjunction with a healthy campus environment, promises to enhance student wellness.

Inhibition of proteoglycan and type II collagen synthesis of disc nucleus cells by nicotine

2003 ◽  
Vol 99 (3) ◽  
pp. 291-297 ◽  
Author(s):  
Keun Su Kim ◽  
S. Tim Yoon ◽  
Jin Soo Park ◽  
Jun Li ◽  
Moon Soo Park ◽  
...  
Keyword(s):  
Phase I ◽  
Nucleus Pulposus ◽  
Phase Ii ◽  
Phase I Study ◽  
Phase Ii Study ◽  
Type Ii Collagen ◽  
Type Ii ◽  
Nucleus Pulposus Cells ◽  
Content Type ◽  
Fine Print

Object. Systemic nicotine has been hypothesized to cause degeneration of the intervertebral disc which in turn decreases vascular supply to the disc through a cholinergic receptor—mediated process. Another possible mechanism may be through direct regulatory effects on disc cells. In this study, the authors tested the hypothesis that nicotine adversely affects nucleus pulposus cells by directly inhibiting proteoglycan synthesis and gene expression of type II collagen (Phase I study). They also assessed the hypothesis that nicotine inhibits the bone morphogenetic protein (BMP)—2-induced upregulation of extracellular matrix (Phase II study). Methods. Cells were isolated from nucleus pulposus obtained in rat lumbar discs and cultured on a monolayer. Media were treated with nicotine and/or recombinant human (rh)BMP-2 for 7 days. Sulfated glycosaminoglycan (SO4-GAG) in media was quantified using 1,9-dimethylmethylene blue (DMMB) assay. Gene assay of types I and II collagen, Sox9, and glyceraldehyde-3-phosphate dehydrogenase were quantified using reverse transcriptase—polymerase chain reaction (RT-PCR) and real time PCR. In the Phase I study, nicotine-treated (100 µg/ml) and nontreated cells were compared. The s-GAG production and messenger RNA (mRNA) of type II collagen and Sox9 decreased significantly in the nicotine-treated group. In the Phase II study, five groups were compared: 1) nontreatment; 2) rhBMP-2 only (100 ng/ml); and 3–5) with rhBMP-2 (100 ng/ml) and increasing doses of nicotine (1 [third group], 10, [fourth group], 100 [fifth group] µg/ml). The SO4-GAG production and mRNA of type II collagen and Sox9 decreased significantly in the groups treated with rhBMP-2 combined with 10 and 100 µg/ml of nicotine compared with the group treated with rhBMP-2. Conclusions. The results of this study raise the possibility that nicotine may contribute to the process of disc degeneration by a direct effect on the nucleus pulposus cells, possibly by antagonizing the effect of BMP-2.

Parametric study on exergy and NOx metrics of turbofan engine under different design variables

2021 ◽  
pp. 1-26
Author(s):  
Hakan Aygun ◽  
Mohammad Rauf Sheikhi ◽  
Mehmet Kirmizi
Keyword(s):  
Nox Emission ◽  
Turbine Engines ◽  
Inlet Temperature ◽  
Gas Turbine Engines ◽  
Turbine Inlet Temperature ◽  
Turbofan Engine ◽  
Performance And Emission ◽  
Decision Mechanism ◽  
Fuel Flow ◽  
Design Variables

Abstract Examining effects of design variables on performance and emission parameters for gas turbine engines is of high importance. In this study, effects of by-pass ratio (BPR) and turbine inlet temperature (TIT) of turbofan engine on energy, exergy and exhaust emissions are parametrically analyzed at 0.85 Ma and 11 km. Moreover, cruise NOx emission is quantified by Boeing Fuel Flow Method 2 (BFFM2) and DLR methods. As a novelty, Specific NOx Production (SNP) is firstly quantified for PW4000 engine. In this context, parametric cycle equations regarding turbofan engine are encoded so as to compute performance and emission metrics. According to energy analysis, specific fuel consumption (SFC) of the turbofan averagely changes from 19.82 to 18.64 g/ kNs due to rising BPR whereas it increases from 18.62 to 19.93 g/kNs owing to rising TIT.Furthermore, exergy efficiency of turbofan rises from 27.67 % to 29.42 % due to rising BPR whereas it decreases from 29.46 % to 27.65 % owing to rising TIT. As for NOx emission results, the higher BPR leads to the lowering of the SNP index of the turbofan from 0.46 to 0.375 g/kNs while the higher TIT yields to the increase of the SNP index from 0.377 to 0.455 g/kNs. According to the findings of this study, decision mechanism could be improved to find out optimum design variables in terms of eco-friendly aircraft activities.

Bewegungstherapie und körperliche Aktivität bei Patienten mit Herzinsuffizienz

Praxis ◽  
2018 ◽  
Vol 107 (17-18) ◽  
pp. 951-958 ◽  
Author(s):  
Matthias Wilhelm
Keyword(s):  
Phase I ◽  
Phase Ii ◽  
Körperliche Aktivität ◽  
Phase Iii

Zusammenfassung. Herzinsuffizienz ist ein klinisches Syndrom mit unterschiedlichen Ätiologien und Phänotypen. Die überwachte Bewegungstherapie und individuelle körperliche Aktivität ist bei allen Formen eine Klasse-IA-Empfehlung in aktuellen Leitlinien. Eine Bewegungstherapie kann unmittelbar nach Stabilisierung einer akuten Herzinsuffizienz im Spital begonnen werden (Phase I). Sie kann nach Entlassung in einem stationären oder ambulanten Präventions- und Rehabilitationsprogramm fortgesetzt werden (Phase II). Typische Elemente sind Ausdauer-, Kraft- und Atemtraining. Die Kosten werden von der Krankenversicherung für drei bis sechs Monate übernommen. In erfahrenen Zentren können auch Patienten mit implantierten Defibrillatoren oder linksventrikulären Unterstützungssystemen trainieren. Wichtiges Ziel der Phase II ist neben muskulärer Rekonditionierung auch die Steigerung der Gesundheitskompetenz, um die Langzeit-Adhärenz bezüglich körperlicher Aktivität zu verbessern. In Phase III bieten Herzgruppen Unterstützung.

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