Labyrinth seals flow field evaluation with optical methods

This work aims to perform the detailed experimental investigation of the flow field in labyrinth seal specimen using optical methods: LDA (Laser Doppler Anemometry) and schlieren visualization. Preliminary tests were performed on a stationary (rotor model with labyrinth does not move), linear – where the curvature of the specimen is omitted – measuring stand supplied by a vacuum pump. The installation makes it possible to achieve critical pressure ratios, up to two. This investigation was also supported by CFD (Computational Fluid Dynamics) calculations performed using the Ansys CFX v.17 commercial code with a flow model based on the RANS equations. Prediction scheme simulated the experimental campaign parameters. In CFD study, different types of mesh resolution were tested, with variable volume discretization in the area of labyrinth fin tip. Presented study shows challenges as well as the possibilities of flow field visualization including three-dimensional vortexes and strong jets occurring downstream the fin tips. Some limitations of LDA method application were pointed out, especially in areas of rapid fluid expansion. Moreover paper presented that schlieren method is a very efficient way of giving the turbulence structures in linear labyrinth seal fins. In the end, experimental results were compared with CFD study, which reviled the best method for labyrinth seal structures flow field simulation. Comparison of experimental and computed results showed some agreement between those two approaches. Flow visualization also allowed to understand better the flow behavior in cavities, which is crucial for design tools development.Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .International centre for heat and mass transfer.American society of thermal and fluids engineers

BFKL versus HERA

The BFKL equation and the kT-factorization theorem are used to obtain predictions for F2 in the small Bjorken-x region over a wide range of Q**2. The dependence on the parameters, especially on those concerning the infrared region, is discussed. After a background fit to recent experimental data obtained at HERA and at Fermilab (E665 experiment), we find that the predicted, almost Q**2 independent BFKL slope lambda >= 0.5 appears to be too steep at lower Q**2 values. Thus there seems to be a chance that future HERA data can distinguish between pure BFKL and conventional field theoretic renormalization group approaches.Comment: 26 pages, 6 eps figures, LaTeX2e using epsfig.sty and amssymb.st

What can whiskers tell us about mammalian evolution, behaviour, and ecology?

Most mammals have whiskers; however, nearly everything we know about whiskers derives from just a handful of species, including laboratory rats Rattus norvegicus and mice Mus musculus, as well as some species of pinniped and marsupial. We explore the extent to which the knowledge of the whisker system from a handful of species applies to mammals generally. This will help us understand whisker evolution and function, in order to gain more insights into mammalian behaviour and ecology. This review is structured around Tinbergen’s four questions, since this method is an established, comprehensive, and logical approach to studying behaviour. We ask: how do whiskers work, develop, and evolve? And what are they for? While whiskers are all slender, curved, tapered, keratinised hairs that transmit vibrotactile information, we show that there are marked differences between species with respect to whisker arrangement, numbers, length, musculature, development, and growth cycles. The conservation of form and a common muscle architecture in mammals suggests that early mammals had whiskers. Whiskers may have been functional even in therapsids. However, certain extant mammalian species are equipped with especially long and sensitive whiskers, in particular nocturnal, arboreal species, and aquatic species, which live in complex environments and hunt moving prey. Knowledge of whiskers and whisker use can guide us in developing conservation protocols and designing enriched enclosures for captive mammals. We suggest that further comparative studies, embracing a wider variety of mammalian species, are required before one can make large-scale predictions relating to evolution and function of whiskers. More research is needed to develop robust techniques to enhance the welfare and conservation of mammals

Truncated Moments and A Generalization of Dglap Equations

We present progress in development of a cut (truncated) Mellin moments (TMM) approach that is constructed to study deep inelastic scattering in lepton-hadron collisions at the natural kinematic constraints. Appropriate classes of TMM for the available experimental kinematic range are discussed. We review some applications of the TMM approach

Truncated Moments and A Generalization of Dglap Equations

We present progress in development of a cut (truncated) Mellin moments (TMM) approach that is constructed to study deep inelastic scattering in lepton-hadron collisions at the natural kinematic constraints. Appropriate classes of TMM for the available experimental kinematic range are discussed. We review some applications of the TMM approach

The assessment of the calculation method for determining characteristics of one straight fin labyrinth sea

The method for the selection of a calculation scheme for the evaluation of the flow behaviour of labyrinth seal with one straight fin, against smooth wall, was presented. Experimental results were obtained from measurement data carried out on the in house, vacuum test section. The advantage of the test rig is a circular shape of the labyrinth specimen, providing similar shape to configuration operated in practise. In computational fluid dynamics study different types of mesh resolution were tested, with variable volume discretization in the area of a labyrinth fin tip. Moreover, a wide range of turbulence models basing on k-ε and k-ω, exploiting the (Reynolds Average Navier Stokes) scheme, for the flow pattern evaluation, were examined. All obtained results were compared with literature data, covering research conducted on similar configurations. The presented study shows challenges as well as the possibilities of calculation simplification and compares results obtained by means of simulations and experiment. The proposed method is characterised by excellent agreement of computational results with experiment data

Truncated Moments in Analysis of Deep-Inelastic Structure Functions of the Nucleon

We present evolution of the Truncated Mellin Moments (TMM) of the parton distributions and structure functions. We illustrate the x and Q2 dependence of the TMM for the polarized case in LO and NLO approximation. We compare the truncated integrals of g1 with COMPASS data

Truncated Moments in Analysis of Deep-Inelastic Structure Functions of the Nucleon

We present evolution of the Truncated Mellin Moments (TMM) of the parton distributions and structure functions. We illustrate the x and Q2 dependence of the TMM for the polarized case in LO and NLO approximation. We compare the truncated integrals of g1 with COMPASS data

Acceptance and performance test of centrifugal pumps

W artykule opisano schemat typowego układu pompowego i pokazano jego statyczne i dynamiczne charakterystyki, istotne przy komputeryzacji ich pomiaru. Przedstawiono skomputeryzowane stanowisko badawcze do wyznaczania podstawowych charakterystyk statycznych i dynamicznych pompy wirowej i rurociągu. Oprogramowanie wspomagające pomiary umożliwia wyznaczenie parametrów energetycznych pompy na podstawie zmierzonych wielkości fizycznych. Stanowisko ułatwia pomiary i opis krzywych rozwoju kawitacji, a także wyznaczenie pełnej charakterystyki kawitacyjnej pompy. Opracowana karta pomiarowa pozwala na ocenę zgodności parametrów nominalnego punktu pracy z parametrami katalogowymi wg obowiązującej normy dla przyjętej klasy maszyny. Przedstawione skomputeryzowane stanowisko badawcze dedykowane jest do pomiarów odbiorczych pomp odśrodkowych.In the paper it is described a schema of typical pump system and it is shown its static and dynamic characteristics which are essential in the process of computerization measurements of the characteristics. Compurized test stand for operational measurements has been presented. The article describes the basic static and dynamic characteristics of a centrifugal pump and pipeline Software aiding measurements make possible to determine pump parameters on the basis of measured physical quantities. Test-stand is labour-saving for measurements, description of cavitational development curves and determination of cavitational pump characteristics. Elaborated measurement card makes possible to compare working point with catalogue parameters