Wyniki wyszukiwania - BazTech

1

Experimental Investigations of Unsteadiness of Flow Fields in Impulse Two-Stage Model Turbine

Krysiński J., Smolny A., Błaszczak J. R.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

|

2015

|

nr 148

53--64

EN

The presented investigations were conducted on a modified impulse two-stage low-pressure model turbine with low-aspect ratio of airfoils. Real impulse turbine geometry has been used for both stages to investigate flow problems. A new supply system maintained very stable conditions at the inlet and flow-calming mesh-wiring and acoustic adaptation were built. These improvements allowed identification of different flow effects. A new measurement system was tested for investigations of influence of phenomena related, among others, to unsteady flow structures connected to vane indexing. It is of key importance for the turbine efficiency measurement.

PL

Przedstawione badania zostały przeprowadzone na zmodyfikowanym stanowisku badawczym niskociśnieniowej dwustopniowej turbiny akcyjnej o małej rozpiętości łopatek. Przy projektowaniu geometrii turbiny do badań zagadnień przepływowych oparto się na geometrii rzeczywistej turbiny. Nowy system zasilania zapewnił bardzo stabilne warunki na wlocie, dodatkowo wstawiono siatki uspokajające oraz adaptację akustyczną. Ulepszenia te zapewniły identyfikację różnych efektów przepływowych. Przetestowano nowy system pomiarowy na potrzeby badań wpływu zjawisk związanych, między innymi, ze strukturami niestacjonarnymi powiązanymi ze zmianą położenia kierownic. Jest to kluczowe zagadnienie z punktu widzenia pomiarów sprawności turbiny.

2

Unsteady three-dimensional MHD flow due to impulsive motion with heat and mass transfer past a stretching sheet in a saturated porous medium

Rajagopal K., Veena P. H., Pravin V. K.

International Journal of Applied Mechanics and Engineering

|

2013

|

Vol. 18, no. 1

137--151

EN

The development of velocity, temperature and concentration fields of an incompressible viscous electrically conducting fluid, caused by impulsive stretching of the surface in two lateral directions and by suddenly increasing the surface temperature from that of the surrounding fluid in a saturated porous medium is studied. The partial differential equations governing the unsteady laminar boundary layer flow are solved analytically. For some particular cases, closed form solutions are obtained, and for large values of the independent variable asymptotic solutions are found. The surface shear stress in x and y directions and the surface heat transfer and surface mass transfer increase with the magnetic parameter and with permeability parameter and the stretching ratio, and there is a smooth transition from the short-time solution to the long-time solution.

3

Shear velocity estimation in hydraulic research

Rowiński P., Aberle J., Mazurczyk A.

Acta Geophysica Polonica

|

2005

|

Vol. 53, nr 4

567-583

EN

Various methods for determination of shear velocity and bed shear stress in hydraulic research are discussed, comprising gravity method, logarithmic profile method, near-bed Reynolds-stress method, turbulent kinetic energy method, Prandtl based method, Saint Venant method, power law method, pipe flow method, Shields method, and direct methods. These methods are, where applicable, used to estimate shear velocity and/or bed shear stress in different fields of hydraulic research, ranging from flows in compound channels, gravel bed rivers, and cohesive sediment erosion studies to flows under unsteady conditions.