The Viscoelastic Swirled Flow in the Confusor

A two-dimensional mathematical model for a steady viscoelastic laminar flow in a confusor was developed under the condition of swirled flow imposed at the inlet. Low density polyethylene was considered as a working fluid. Its behavior was described by a two-mode Giesekus model. The proposed mathematical model was tested by comparing it with some special cases presented in the literature. Additionally, we propose a system of equations to find the nonlinear parameters of the multimode Giesekus model (mobility factor) based on experimental measurement. The obtained numerical results showed that in a confusor with the contraction rate of 4:1, an increase in the swirl intensity at Wi < 5.1 affects only the circumferential velocity, while the axial and radial velocities remain constant. The distribution pattern of the first normal stress difference in the confusor is qualitatively similar to the one in a channel with abrupt contraction, i.e., as the viscoelastic fluid flows in the confusor, the value of N1 increases and reaches a maximum at the end of the confusor. Dimensionless damping coefficients of swirl are used to estimate the swirl intensity. The results show that the swirl intensity decreases exponentially.

Estimation of Factors that Affect the Metrological Characteristics of Target Flow Meters

The article is devoted to the effective system crea­tion for recording liquids and gases flows. There is extremely relevant for creating metering units of fuel and energy resources. The aim of the work is to determine the influence of the flowed body geometric configuration of the sensitive element and its orientation relative to the direction of the flow on the hydrodynamic flow meter metrological characteristics, as well as determining the instruments’ rational location in the technological line Based on the example of the hydrodynamic class measuring transducers factors that have a significant impact on their metrological characteristics are determined, the degree of the transducers sensitivity to the measured medium flows asymmetry is revealed. The flows asymmetry is simulated by hydraulic resistan­ces of different spatial configurations (spatial elbow, elbow, double elbow, contraction, abrupt contraction). Simulation modeling of the operation of such devices is performed. Sensitive elements of different Gaussian curvatures such as zero (cylinder), positive (cone) and negative (hollow hemisphere) were studied. The value of the registration result uncertainty depends on the flow asymmetry and the instrument spatial orientation relative to the vertical axis in the technological network. The obtained results make it possible to clearly determine the instrument installation place in the technological network under conditions of maximum accuracy and minimal impact on the measured medium. This allows effectively using transducers in places of the technological network, taking into account the specific conditions for the metering units creation. There is no ne­cessary to make straight pipeline sections before and after the instruments. The researches results show that measuring instruments with flow bodies in the shape of a cone oriented the apex toward the flow are the best.