Disintegration of a liquid sheet due to gravity force

An experimental study was made of the disintegration of a liquid sheet due to gravity force. The influence of surface tension, viscosity, and density of liquids on the phenomenon of disintegration was found. Conditions of liquid sheet breaking into streams, as well as the frequency of appearance of streams and the mean diameter of droplets independent of properties of the liquid, were found experimentally

Towards to efficiency maximum within a pressure increasing process

The article presents a mathematical description of compression process in a pump and an original concept to increase efficiency in this process

Numerical analysis of adaptive control in LP turbines

A new design idea of adaptive control in LP steam turbines under conditions of (1) extraction of steam to the extraction point and (2) seasonal changes of pressure in the condenser is discussed. Nozzle blades of a stage located directly downstream of the extraction point or of the exit stage located upstream of the exit diffuser have adjustable trailing edges that can adapt the geometry of the blading system to the changing flow conditions. The idea has been validated numerically on a group of two exit stages of a 60MW extraction/condensation turbine. A series of flow calculations have been performed using a FlowER code for solving the flow of compressible viscous gas in a 3D turbomachinery environment. As a result, characteristics of the design, including the mass flow rate, flow angles in characteristic sections, enthalpy losses and turbine power, have been obtained in a range of given pressure drops and nozzle blade stagger angles. Based on these characteristics, the adequate position of the nozzle blade has been found to adapt the stage (stage group) geometry to the changing flow conditions. The advantages of adaptive control in the form of increased turbine efficiency and power have also been estimated

Qualitative comparison of 2D and 3D computation of flow field in the cone shaped turbine nozzle

The paper presents a qualitative comparison of 2D and 3D computation of the flow field in a cone shaped turbine nozzle. The calculation yields a surface, S/sub 2/, for a given conical stream surface S/sub 1/. The S/sub 2/ stream surface represents the curvature of blading passages. This formulation is typical for the inverse problem. Based on a surface it is possible to design the shape of the blade. Results of 3D computation by means of FLUENT have been presented and compared with assumptions in the 2D model

Zadanie odwrotne dla sprężarki promieniowej o hiperbolicznym kształcie

A comparison between the inverse method, leading within the framework of the 2D model to prediction of the optimal rotor shape and the direct approach for evaluating flow through a preexisting rotor shape utilizing a 3D model is presented in this paper. The principle of shaping the rotor envelope and blading within the 2D model is illustrated, followed by subsequent computation of 3D flow through the resulting model. The design goal is to obtain uniform distributions of flow parameters within the rotor while avoiding separated flow. It is also shown how the altering of the overall shape of the rotor from conical to hyperboloidal affects the uniformity of velocity distribution upstream of the rotor inlet.Porównano rozwiązanie zadania odwrotnego w ramach modelu dwuwymiarowego, prowadzącego do kształtu koła wirnikowego, z zadaniem prostym rozwiązanym w ramach modelu trójwymiarowego dla skonstruowanego wirnika. Przedstawiono elementy algorytmu kształtowania łopatek przy wykorzystaniu modelu dwuwymiarowego. W podanym przykładzie wskazano możliwość optymalizacji kształtu jednego z ograniczeń kanału w celu uzyskania równomiernego rozkładu parametrów w przekroju wylotowym. Pokazano jak zmiana obrysu wirnika z klasycznego kształtu stożkowego na hiperboliczny może wpłynąć na równomierność rozkładu pól prędkości przed układem łopatkowym

1D model calibration based on 3D calculations for Tesla turbine

This paper presents a system of equations for an axisymmetric laminar flow, after averaging, through the width of the interdisk slit of a Tesla turbine. Coefficients improving the efficiency of a 1D model were introduced as a result of averaging. The minimal number of such coefficients was determined. The 1D model makes it possible to attain analytical solutions to an accuracy limited by these coefficients. The calibration of a 1D model depends on finding the numerical values of coefficients that yield a sufficient accuracy compared with 3D calculations. A definition of the efficiency coefficient for the Tesla turbine is also given. This definition relies on the 1D model results. Example values of this coefficient are described after the 1D model calibration

A method for analysing ram pressure characteristics of impeller pump rotor

This paper presents a method in which typical tests of centrifugal pump are used to obtain information on real value of discharge angle of flow leaving the rotor. The method can be applied to properly choose inlet angle to blade palisade of centrifugal guide vanes in the case when to perform measurements of velocity fields behind the rotor more precisely is not possible

Method of characteristics for design of centrifugal pump geometry

The method of characteristics leads to the blade geometry of a centrifugal pump. The method is built taking the advantage of the governing equations of fluid mechanics written in a non-orthogonal coordinates system. The coordinate system is based on an analytically described boundary of a centrifugal pump. Some of the information concerning the designed geometry should be introduced in advance. The mass conservation equation needs the information of the blockage factor resulting from the blading thickness. In the momentum conservation equation the body force replaces the blading force together with the friction force. In the energy conservation equation the dissipation effects are represented by a loss coefficient. It is shown that while simplifying the body force vector, the set of equations reduces to a hyperbolic system which allows applying the method of characteristics. The shapes of surfaces representing the designed blading can be built from the trajectories of fluid particles