Nastavení ochran a selektivity v průmyslových sítích

Diploma thesis is focused on a theme – “Protection Settings and Selectivity in Industrial Network”. Content of the thesis include protection settings calculations - mainly, overcurrent and ground-fault protection functions. Also, diploma contains selectivity charts for the equipment used in the given industrial network. Electrical equipment were predefined by a customer and were tested with a load flow calculation in a software. For the protection purposes short-circuit currents were calculated as well.Diplomová práce je zaměřena na nastavení ochran a selektivity v průmyslových sítích.410 - Katedra elektroenergetikyvýborn

Experiments on the Artificial Disturbance Evolution in 2D and 3D Spanwise Modulated Boundary Layers at Mach 2 and 2.5

AbstractExperimental data on the nonlinear wave train development in 3D supersonic boundary layer over swept wing and experimental investigation of wave train development in spanwise modulated boundary layer on flat plate and swept wing at Mach number 2 and 2.5 are presented. Artificial disturbances in the boundary layer were excited by periodical glow discharge mainly at 10 and 20kHz. It was found, that some disturbance excitation downstream cannot be explained by linear stability theory. It was obtained that receptivity of supersonic boundary layer to the surface excited controlled pulsations and the wave train development essentially depends on the Mach number

Numerical simulation on the development of periodic three-dimensional disturbances in a supersonic boundary layer

The results of a numerical study of the development of periodic pulsations in a supersonic boundary layer on a flat plate are presented at a Mach number of 2.5 and a unit Reynolds number of 8×106 m–1. Using the software complex ANSYS, the complete Navier-Stokes equations were solved. Periodic mass flow disturbances with a frequency of 20 kHz were introduced into the boundary layer through a small-diameter hole on the surface of the model. Downstream the profiles of the longitudinal mass flow pulsations were recorded, and spectral analysis of the data was carried out. The main characteristics of the development of unstable disturbances in both physical and wave spaces are obtained

On the development of controlled stationary and travelling disturbances in the supersonic boundary layer of a swept wing

Experimental data on the evolution of controlled stationary and travelling disturbances in a 3D supersonic boundary layer, over a 45° swept-wing at Mach number 2.0, is presented. Travelling artificial disturbances were introduced in the boundary layer by periodical glow discharge, at a frequency of 20 kHz. Stationary disturbances were acquired by setting the roughness elements on the surface of the model. Spatial-temporal and spectral-wave characteristics of the wave train at the frequency 20 kHz, in the linear region of development, were obtained. It was found that the periodic modulation of mean flow can lead to the stabilization of unstable travelling disturbances in the supersonic boundary layer of a swept wing. These experiments have investigated the viability of using roughness elements to control laminar-turbulent transition

On the development of controlled stationary and travelling disturbances in the supersonic boundary layer of a swept wing

Experimental data on the evolution of controlled stationary and travelling disturbances in a 3D supersonic boundary layer, over a 45° swept-wing at Mach number 2.0, is presented. Travelling artificial disturbances were introduced in the boundary layer by periodical glow discharge, at a frequency of 20 kHz. Stationary disturbances were acquired by setting the roughness elements on the surface of the model. Spatial-temporal and spectral-wave characteristics of the wave train at the frequency 20 kHz, in the linear region of development, were obtained. It was found that the periodic modulation of mean flow can lead to the stabilization of unstable travelling disturbances in the supersonic boundary layer of a swept wing. These experiments have investigated the viability of using roughness elements to control laminar-turbulent transition

Numerical simulation on the development of periodic three-dimensional disturbances in a supersonic boundary layer

The results of a numerical study of the development of periodic pulsations in a supersonic boundary layer on a flat plate are presented at a Mach number of 2.5 and a unit Reynolds number of 8×106 m–1. Using the software complex ANSYS, the complete Navier-Stokes equations were solved. Periodic mass flow disturbances with a frequency of 20 kHz were introduced into the boundary layer through a small-diameter hole on the surface of the model. Downstream the profiles of the longitudinal mass flow pulsations were recorded, and spectral analysis of the data was carried out. The main characteristics of the development of unstable disturbances in both physical and wave spaces are obtained

Experimental and numerical investigation of excitation of artificial disturbances in the supersonic boundary layer

The influence of the parameters of the impulse action on the laminar supersonic flat-plate boundary layer on the excited localized perturbations is investigated at Mach 2. The influence of the duration of a pulsed discharge on the generated disturbances is studied experimentally. Also, a direct numerical simulation of the influence of the parameters of pulse injection on generated perturbations is carried out. It is obtained that as the duration of the action on the supersonic boundary layer increases, the amplitude of the generated disturbance increases. The velocity of the propagation downstream of localized disturbances in Mach 2 supersonic flat-plate boundary layer is estimated

Experimental and numerical investigation of excitation of artificial disturbances in the supersonic boundary layer

The influence of the parameters of the impulse action on the laminar supersonic flat-plate boundary layer on the excited localized perturbations is investigated at Mach 2. The influence of the duration of a pulsed discharge on the generated disturbances is studied experimentally. Also, a direct numerical simulation of the influence of the parameters of pulse injection on generated perturbations is carried out. It is obtained that as the duration of the action on the supersonic boundary layer increases, the amplitude of the generated disturbance increases. The velocity of the propagation downstream of localized disturbances in Mach 2 supersonic flat-plate boundary layer is estimated