Strongly swirling vortex chamber flows are examined experimentally and numerically using the Reynolds stress model (RSM). The predictions are compared against the experimental data in terms of the pressure drop across the chamber, the axial and tangential velocity components, and the radial pressure profiles. The overall agreement between the measurements and the predictions is reasonable. The predictions provided by the numerical model show clearly the forced and free vortex modes of the tangential velocity profile. The reverse flow (or back flow) inside the core and near the outlet, known from experiments, is captured by the numerical simulations. The swirl number has been found to have a measurable impact on the flow features. The vortex core size is shown to contract with the swirl number which leads to higher pressure drop, higher peak tangential velocity, and deeper radial pressure profiles near the axis of rotation. The adequate agreement between the experimental data and the simulations using RSM turbulence model provides a valid tool to study further these industrially important swirling flows.

A discrete, non-linear, time-varying, torsional dynamic model of a multi-stage planetary train that is formed by any number of simple planetary stages is proposed in this study. Each planetary stage has a distinct fundamental mesh frequency and any number of planets spaced in any angular positions. The model allows the analysis of the gear train in all possible power flow configurations suitable for various gear drive ratios. It includes periodic variation of gear mesh stiffnesses as well as clearance (backlash) non-linearities that allow tooth separations. Equations of motion for the general case are formulated and solved semi-analytically using a hybrid harmonic balance method (HBM) in conjugate with inverse Fourier transform. Relative mesh displacements along lines of action of individual gear pairs were used as the continuation parameters to pass singular points and ill-conditioned equations in their proximity. At the end, a case study of a two-stage planetary train is used to demonstrate the effectiveness of the model and solution methods. The HBM solutions are compared to those obtained by a direct numerical integration method to assess their accuracy.

In this article we examine confined swirling flows using the integral equations of continuity and energy, along with the minimum pressure criterion. The pressure drop and the core size have been studied in the swirling confined vortex chamber. Both the n = 2 vortex model, with reverse and non‐reverse flow, and the free vortex model have been used at the vortex chamber exit plane. The influence of vortex chamber geometry, such as contraction ratio, inlet angle, area ratio, aspect ratio, and Reynolds number, on the flow field has been analyzed and compared with the present experimental data. The pressure drop across the vortex chamber differs from that in pipe flow, due to the mechanism of swirl flow that depends mainly on the intensity of tangential velocity. If the chamber length is increased, the vortex decays producing a weaker tangential velocity (less centrifugal force) that leads to less pressure drop. Based on the present theory, a new approach to determine the tangential velocity and radial pressure profiles inside the vortex chamber is developed and compared with the available experimental data. It shown that the n = 2 vortex model with reverse flow gives better results for strongly swirling flow.

No abstract

The study aims to identify the degree to which students of earth and environmental sciences at Yarmouk University represent Islamic educational environmental values, and to reveal whether there are differences in the degree of assimilation due to the variables of sex and academic year. To achieve the objectives of the study, the descriptive survey approach was used, and a questionnaire was prepared consisting of (50) items, distributed into (7) areas, and was applied to a sample of (110) male and female students. The results showed that the degree of students’ representation of Islamic environmental educational values is high, and that there are statistically significant differences in the students’ representation of the Islamic environmental educational values due to the academic level and for the benefit of students of levels (second and fourth) compared to first-level students, while there are no significant differences in the degree that represents Students' environmental values are attributed to the student's gender, or to the interaction between gender and academic level. The study recommended the adoption of environmental values stemming from the Noble Qur’an and the Sunnah of the Prophet, and include it in the plans and courses of university programs, and all institutions must play their role in spreading environmental awareness among members of society.

This article presents a numerical analysis of multi-phase flow with powerful swirling streams in a cylindrical separator equipped with two vortex generators in an attempt to predict the separation efficiency of an air-water mixture. New design of a cylindrical separator is introduced for air-water mixture.The mixture multiphase and large eddy simulation (LES) turbulence models were applied. Images that concern velocity field, pressure, and volume fraction are introduced. Air phase is trapped and localized along the centerline of the separator and then migrates toward the upper exit hole, while water phase is distributed and rotated along the wall, then confined at the mid-separator due to two strong clock-wise centrifugal forces before it is expelled through its exit at mid of separator. It was found that the separation efficiency at constant Reynolds number of 8×10 4 with two feeding volume fractions of 95% and 90% are 97.8% and 96.1%, respectively. Also, the separation efficiency at constant feeding volume fraction of 95% with two Reynolds numbers of 2×10 5 and 8×10 4 are 98.6% and 97.8%, respectively. It is revealed that the separation efficiency will increase as the Reynolds number increases and/or increasing the volume fraction.

No abstract

No abstract