A Model to Assess the Risk of Ice Accretion Due to Ice Crystal Ingestion in a Turbofan Engine and its Effects on Performance

The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that were attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was one or more of the following anomalies: degraded engine performance, engine roll back, compressor surge and stall, and flameout of the combustor. The main focus of this research is the development of a computational tool that can estimate whether there is a risk of ice accretion by tracking key parameters through the compression system blade rows at all engine operating points within the flight trajectory. The tool has an engine system thermodynamic cycle code, coupled with a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor blade rows. Assumptions are made to predict the complex physics involved in engine icing. Specifically, the code does not directly estimate ice accretion and does not have models for particle breakup or erosion. Two key parameters have been suggested as conditions that must be met at the same location for ice accretion to occur: the local wet-bulb temperature to be near freezing or below and the local melt ratio must be above 10%. These parameters were deduced from analyzing laboratory icing test data and are the criteria used to predict the possibility of ice accretion within an engine including the specific blade row where it could occur. Once the possibility of accretion is determined from these parameters, the degree of blockage due to ice accretion on the local stator vane can be estimated from an empirical model of ice growth rate and time spent at that operating point in the flight trajectory. The computational tool can be used to assess specific turbine engines to their susceptibility to ice accretion in an ice crystal environment

Simulation of Fluid Flow and Collection Efficiency for an SEA Multi-element Probe

Numerical simulations of fluid flow and collection efficiency for a Science Engineering Associates (SEA) multi-element probe are presented. Simulation of the flow field was produced using the Glenn-HT Navier-Stokes solver. Three dimensional unsteady results were produced and then time averaged for the collection efficiency results. Three grid densities were investigated to enable an assessment of grid dependence. Collection efficiencies were generated for three spherical particle sizes, 100, 20, and 5 micron in diameter, using the codes LEWICE3D and LEWICE2D. The free stream Mach number was 0.27, representing a velocity of approximately 86 ms. It was observed that a reduction in velocity of about 15-20 occurred as the flow entered the shroud of the probe.Collection efficiency results indicate a reduction in collection efficiency as particle size is reduced. The reduction with particle size is expected, however, the results tended to be lower than previous results generated for isolated two-dimensional elements. The deviation from the two-dimensional results is more pronounced for the smaller particles and is likely due to the effect of the protective shroud

Дистанційне навчання як принцип відкритого заняття

Summary. Distance learning is gaining among technologies based on the principles of open learning. This technology widely uses computer curricula for various purposes and modern telecommunications to communicate directly with a student at a distance. The idea of ​​this technology is the interaction of a teacher and a student in a virtual space: both of them are at their computers or gadgets and communicate via the Internet. Distance learning also plays an exceptional role in the modernization of education. In the conditions that have arisen due to the pandemic, students and academic staff should be sensitive to the need to work in forced remote conditions with a more practical and conscious approach to overcoming the existing digital barriers in the education system.Резюме. Среди технологий, основанных на принципах открытого обучения, больших оборотов набирает дистанционное обучение. Эта технология широко использует компьютерные учебные программы различного назначения и современные телекоммуникации для общения непосредственно со студентом на расстоянии. Идеей этой технологии является взаимодействие преподавателя и студента в виртуальном пространстве: оба они находятся у своих компьютеров или гаджетов и общаются с помощью сети «Интернет». Также в модернизации образования исключительную роль занимает дистанционное обучение. В условиях, возникших из-за пандемии, студенты и научно-педагогические работники должны с пониманием относиться к необходимости работать в вынужденных дистанционных условиях с более практичным и осознанным подходом к преодолению существующих цифровых барьеров в системе образования.Резюме. Серед технологій, що базуються на принципах відкритого навчання, великих обертів набирає дистанційне навчання. Ця технологія широко використовує комп᾽ютерні навчальні програми різного призначення та сучасні телекомунікації для спілкування безпосередньо із студентом на відстані. Ідеєю цієї технології є взаємодія викладача і студента у віртуальному просторі: обидва вони знаходяться біля своїх комп᾽ютерів або гаджетів і спілкуються за допомогою мережі «Інтернет». Також у модернізації освіти виключну роль займає дистанційне навчання. В умовах, що виникли через пандемію, студенти і науково-педагогічні працівники повинні з розумінням ставитися до необхідності працювати у вимушених дистанційних умовах із більш практичним та усвідомленим підходом до подолання існуючих цифрових бар᾽єрів у системі освіти

Recent Advances in the LEWICE Icing Model

This paper will describe two recent modifications to the Glenn ICE software. First, a capability for modeling ice crystals and mixed phase icing has been modified based on recent experimental data. Modifications have been made to the ice particle bouncing and erosion model. This capability has been added as part of a larger effort to model ice crystal ingestion in aircraft engines. Comparisons have been made to ice crystal ice accretions performed in the NRC Research Altitude Test Facility (RATFac). Second, modifications were made to the run back model based on data and observations from thermal scaling tests performed in the NRC Altitude Icing Tunnel

Self-regulation and the foraging gene (PRKG1) in humans

We would like to thank Dr. Sara Mostafavi (University of British Columbia) for directing us to the CMC website regarding gene expression for rs13499 and for statistical advice. This work was supported by NSERC Discovery funds to JD and a Canadian Institute for Advanced Research award to MS.Peer reviewedPostprin

Statistical considerations for genome-wide scans: design and application of a novel software package POLYMORPHISM

OBJECTIVE: Given the cost and complexity of genome-wide scans, optimization of study design is of critical importance. Available algorithms only partially satisfy this need. We designed a software package called 'POLYMORPHISM' to meet these needs. METHODS: The program is designed to calculate linkage parameters for both 'single-point' and 'two-point' settings that are applicable also to incompletely informative microsatellite markers. In single-point analysis, the heterozygosity, polymorphism information content (PIC) and linkage information content (LIC) statistics based on marker allele frequencies are provided. In two-point analysis, joint PIC values for two markers, the conditional probability of detecting linkage phase, the frequency of double heterozygotes and the expected number of informative meioses are calculated. RESULTS: Results were obtained using S.A.G.E./DESPAIR (Design of Linkage Studies Based on Pairs of Relatives) in addition to applying this program to a Centre d'Etude du Polymorphisme pedigree-derived genotyping data set, which estimated critical parameters used in a two-stage genome scan. A single nucleotide polymorphism (SNP)-based one-stage genomic screen strategy is also considered. CONCLUSIONS: LIC values are crucial for getting accurate estimates on those parameters that are important for a two-stage genome screening study. Optimization of the cost-effectiveness of an SNP-based genomic screen strategy is possible by modeling a balance between marker information content and marker density

Effect of weather conditons on cereals yielding cultivated in the Experimental Station in Zawady

W pracy przedstawiono charakterystykę warunków glebowo-klimatycznych Rolniczej Stacji Doświadczalnej w Zawadach, należącej do Uniwersytetu Przyrodniczo-Humanistycznego w Siedlcach, podano powierzchnię zasiewów, plony ziarna i zbiory czterech roślin zbożowych (żyta ozimego, pszenżyta ozimego, pszenżyta jarego i pszenicy jarej). W warunkach glebowo-klimatycznych RSD na największej powierzchni uprawiane było pszenżyto ozime, które plonowało na najwyższym poziomie, co pozwoliło uzyskać największe zbiory. Natomiast najmniejszy plon ziarna uzyskano z żyta ozimego i pszenicy jarej. Plon ziarna zbóż w latach badań był różnicowany przez warunki opadowo-termiczne. Różnica plonu ziarna w odniesieniu do średniej z dziesięciolecia wahała się od -36,5% do +58,3%, w zależności od lat i gatunku.The paper presents the characteristics of soil and climate conditions at the Experimental Station in Zawady, belonging to University Of Natural Sciences And Humanities in Siedlce, cultivated area, grain yields and harvest the four species of cereals were given (winter rye, triticale, spring triticale and spring wheat). In soil and climatic conditions in the area of RSD on the largest area triticale was planted, which harvested on the highest level, which let to get the largest yields. But the lowest grain yield was taken from winter rye and spring wheat. Cereal grain yield in research years was differed by conditions of rain and temperature. Difference in grain yield in relation to the average of the decade ranged from - 36.5% to 58.3%, depending on years and species

The Anatomic Structure of Pulmonary Arteries as a Source of Unreliability in Thermodilution Cardiac Output Measurement

One of the most fundamental examination in intensive care medicine is cardiac output measurement, realized by pulmonary artery catherization. The thermodilution cardiac output estimation method is not resistant to various kinds of disturbances, which significantly decreases its sensitivity and specificity. The paper depicts investigations related to analysis of presumable new source of unreliability - asymmetric blood flow through pulmonary vessels. The investigations consisted of two phases: clinical examination (to obtain anatomical data) and computer modeling (to simulate the flow symmetry)