Unsteady Fluid Flow and Heat Transfer Through a Porous Medium in a Horizontal Channel with an Inclined Magnetic Field

This paper investigates the unsteady flow and heat transfer of a viscous, incompressible, and electrically conducting fluid through a porous medium in a horizontal channel. The basic physical properties of the fluid and the porous medium are constant. The fluids considered are those with the Prandtl number less than 1. The channel walls are made of horizontal permeable plates, which are at constant but different temperatures. Fluid suction/injection through the plates occurs at a velocity perpendicular to the plates, whose intensity is a cosine function of time. The applied external magnetic field is homogeneous and inclined in relation to the transverse plane of the channel. The problem is dealt with through an inductionless approximation. Fluid flow is instigated by constant pressure drops along the channel. The equations used to describe the problem are transformed to dimensionless forms and solved analytically using the perturbation method. Approximate analytical expressions for dimensionless fluid flow velocity and dimensionless temperature are determined as functions of the following physical parameters: Prandtl number, Hartmann number, porosity factor, frequency, amplitude, and magnetic field inclination angle. Numerical results are presented as diagrams and tables and are used to analyse the influence of physical parameters on the fluid flow velocity and temperature

Mathematical Modeling of Heat Transfer of Liquefied Natural Gas Engines

The article presents a mathematical model for pressure growth in the line supplying the engine KAMAZ with cryogenic fuel under specific insulation conditions. By using the heat balance equation the model in a simple linear form is obtained. This makes the model suitable for use in solving practical tasks related to the design of a liquefied natural gas engine fuel system. According to the above-mentioned method, the geometric parameters of the section of the main elements are determined under different external conditions and the boundary parameters of the gas fuel (maximum and minimum values of pressure, temperature, and flow). These data are necessary to determine the consumption, hydraulic and project features of the project. Fuel pipes are optimized (for hydraulic resistance, pressure and flow impulses, structural strength) to improve the accuracy of fuel dosing. The adequacy of the model was tested on a special modified test stand

VALVE SELECTION FOR THE PURPOSE OF REDUCING THE WATER HAMMER EFFECT IN A PRESSURIZED PIPELINE

This paper discusses the gravity-fed hydraulic system, which consists of the upper reservoir, the lower reservoir, the pipeline, and valves. To achieve simpler and more efficient protection of a system against water hammer, it is advisable to establish conditions in which the pressure rises as little as possible during transient regimes without using any protective equipment. The discussion focuses on the pressure rise caused by different valve types: butterfly, needle, and ball valves, as well as two valve closure intervals – 20 and 40 seconds. The systems considered have nominal diameters of DN 300 and DN 600. The problem was studied using a simulation of unsteady flow regimes of hydraulic transport. The obtained results regarding the maximum pressure rise due to water hammer were used to select the most satisfactory control valve for the considered hydraulic system

An exploratory study of Nantou Ancient Village revitalisation focusing on visual, cognitive and structural aspects

In the absence of spatial diversity, there is a need for additional elements that will enable the recognition of the space in which we are. These elements are landmarks. In order for a certain thing to be considered a landmark, it must be unique and recognisable either by its properties (size, shape, colour, materialisation, etc.) or by the location where it is located in space. Landmarks and zones with a strong character provide a strong identification of the space with its peculiarity. This paper analyses the identity of the urban settlement of Nantou Old Town as a historical cluster located in the attractive location in the Nanshan District of Shenzhen City, with over 800 residential and commercial units. The study was conducted experimentally on a number of respondents who are regular or occasional consumers in Nantou settlement, through a closed questionnaire, from which we got answers to the initial questions: how successful is the revitalisation of this cultural-historical settlement, what are the landmarks, how simple is orientation through the settlement and what method is most common in wayfinding (landmark or navigation app), does a consumer’s choice in wayfinding device and landmark physical characteristics (colour, texture and form) depend on personal dimensions (gender, age, educational level and familiarity with environment)