Power engineering and energy generating technologies

Current velocities in the boundary layer over the plate with semi-cylindrical cavity

In this study, we made the hot-wire anemometry measurements of the velocity field over the plate with local cavity in the open-circuit wind tunnel. We investigated the laminar and turbulent flows in the range of Reynolds numbers in regard to the plate length (from its start to the cavity site) 4•104–7•105. On the experimental side, we presented the mean longitudinal velocity profiles along the plate and over the cavity.

Modeling of hydrodynamics and heat exchange in the initial area of round pipe at the separated flow

Employing the method of computational modeling, we study the area of separated flow of the initial section of the round straight tube. It has the input sharp edge angled 90°. Moreover, we develop the CFD-model that allows calculating the heat hydrodynamic parameters of the stream in the separated flow in the range of Reynolds numbers from 28⋅103 to 110⋅103. Based on the results of measuring the dimensional field of static pressures and local heat transfer in the initial section of the round tube, we verify the applied numerical models.

Using Pair-Wise Comparison Methods for Determining the Priority of Methods for Providing Static Stability of Induction Motors under Conditions of Multicriterion Choice

In this paper, we compare Way, Saaty, Cogger & Yu methods to determine the weight coefficients of optimization criteria importance in the problem of obtaining the optimal sequence of using the main methods of increasing the static stability of induction motors. Finally, our research results show that Saaty method is the optimal method for solving this problem

Modeling of Film Hydrodynamics in the Grid Structure

Our objective is to determine the speed and thickness of the film as principal parameters that present the efficiency of heat mass transfer. To that end, we apply an analytical model of flow infinite cylinder by the perpendicular flow of inviscid fluid. The model is supplemented with the calculation of local liquid film thickness. The experimental results show that the waves appear on the grid surface with the film. It causes the increase of the flow velocity and reduction of the film thickness.

Influence of the Quality of Electrical Energy and Technical Conditions of Induction Motors on their Static Stability

The paper provides insights into the research of static stability of induction motors at a low-quality supply voltage and an unsatisfactory technical condition of the motor. The dP/ds criterion of static stability of the induction motor was used to assess its static stability. The results obtained show that a non-symmetric voltage has a negative influence on the static stability of the induction motor by decreasing the component of a positive-sequence voltage.

The analysis of asynchronous engine self-start at asymmetry in the system

In this paper, we elaborate the mathematical model and algorithm for determination of the self-start conditions at voltage asymmetry in the power system. Moreover, we make the trial calculations of the engine self-start and develop the programmes in the MatLab environment for the calculation of the asynchronous engine self-start.

Characteristics of electric field measuring device

This paper considers mathematical expressions for mean values of the electric field tension depending on spatial orientation of the measuring device – a metallic sphere for measuring the tension of electric field. We also obtain component parts of instrumental errors caused by sizes of its aerials.

Research into thermal tension in rotary kilns with Vortex Heat Exchangers

We develop the mathematical model and algorithms to determine the stress-strain state of a rotary kiln, taking into account mass forces and heat loads. We study operating conditions of the vortex heat exchanger in a furnace size 460m, determine stress and analyze the calculation results on design elements of the heat exchanger and the furnace.

A Simplified Mechanical Model of a Chain of Granulated Material Elements

Our study focuses on a simplified mechanical model of the separate part of a granulated material layer. This layer is represented as a chain of two kinds of elastic elements (elastic element, interlayer). The intensity of compression stress changing considerably decreases in the chain with elastic elements and interlayers at a certain quantity of elements. The influence of the compression stress on a contact resistance can be neglected starting from this quantity.

Optimal data filtration based on kalman’s algorithm for temperature control of the power generating unit under considerable industrial noise influence

In this paper, we utilize the Kalman’s filtration algorithm for processing the real data obtained from the temperature control system. This data consists of a complex combination of various noises. We prove that the Kalman’s filter satisfies the required filtration quality. Moreover, it can continuously process the data unlike traditional and previously used methods of programmatic filtration. Therefore, our method can be used by automatic control experts for data filtration of complex combination of noises in the field of heat power engineering.