Vol 50, No 1 (2016)

Results are presented of experiments carried out using an air model of a hydraulic turbine draft tube. These included velocity measurements in the conical part of the tube using a laser-Doppler anemometer and measurement of pressure pulsations using acoustic sensors (microphones). It is shown that a system of two runner vane cascades can be used to simulate a velocity distribution that resembles the distributions downstream of a runner under full-scale conditions. Experiments show that modes involving the formation of a vortex rope occur in the region of significant hydroelectric generating unit underload. Analysis of spectra, the cross-correlation function, and mean velocity distributions confirmed the vortex nature of the generation of powerful pressure pulsations in the draft tube cone.

Studies at one of the earthen dams of the Volga – Kama cascade of dams revealed an elevated removal of suspended particles in seepage water, resembling the process of mechanical erosion. Comprehensive studies show that active microbiological processes occur in dam bodies. Elevated turbidity of seepage water was caused by microbiological processes. Microorganisms are also capable of adversely affecting the physical and mechanical properties of soil and promote the risk of reducing the stability of hydraulic engineering installations. In this regard, there is a need to develop a method to study the extent of microbiological process hazard and to incorporate it into regulatory documents.

are presented of measurements carried out to determine elastic wave velocity in the rock massif in the bed of the Sayano-Shushenskaya HPP. A significant increase has been noted in longitudinal and transverse wave velocities and in the thickness of exogenous zones, as compared to values obtained during the survey phase and determined in the post-construction period. One of the principal reasons for the observed change in the thickness and properties of zones (subzones) of diverse rock massif integrity in the dam bed is the technogenic stresses transmitted by the facility to the massif. Changes that trend (i.e., occur unidirectionally over time) and vary due to variations in reservoir water level were identified in the properties and state of the massif under study.

The results are presented of the major activities undertaken by the Geodynamic Research Centre during the final stage of Boguchanskaya hydroproject construction.

Functional dependencies are established for the characteristics of seismic transients recorded at various points of a studied site, which are used to propose a new approach to seismic microzonation (SMZ) that enables the creation of new SMZ maps of strong seismic motion, with due regard for dynamic parameters of recorded transients during weak earthquakes.

A computational and experimental investigation of the processes occurring in premix combustors with swirl stabilization similar to that used in modern gas-turbine engines is described. The combustor burner consists of main and pilot burners. The combustor operates on a mixture of natural gas and air with excess air coefficient from 10 to 2.6. The influence of the fuel fraction in the pilot burner (PFR) with fixed excess air coefficient á on the macrostructure of the flame — the relation between the shape and position of the flame front and the dominating structures of the flow — is examined. The flame front is investigated by means of three-dimensional numerical modeling. Four ma xxx crostructures are observed in the experimental PFR range from 0 to 100% with fixed excess air coefficient á. It is shown that each form of high-frequency combustion instability corresponds to a definite macrostructure of the flame. It is noted that the fuel fractions in the pilot burner at which changes are observed in the flame configuration are associated with the appearance of thermo-acoustic instability.

An algorithm for calculating the maximum allowable active power flows in controlled sections from the steady-state and transient stability conditions is developed. Computations for a test circuit of the power system are conducted using software that implements the algorithm. The results of the computations are in agreement with those obtained with well-known software systems.

The primary current of a current transformer (CT) is calculated on the basis of the characteristics of the magnetization and the measured secondary current of the CT. This makes it possible to extend the linear range of operation of the measuring circuit of the protection and thereby increase the protection stability. The mathematical model of a current transformer and the reset algorithm for the primary and magnetization currents are described and the operation of the algorithm in different transient processes is analyzed.

Consideration is given to different approaches to modeling the control systems of gas turbines as a component of CCPP and GTPP to ensure their reliable parallel operation in the UPS of Russia. The disadvantages of the approaches to the modeling of combined-cycle units in studying long-term electromechanical transients accompanied by power imbalance are pointed out. Examples are presented to support the use of more detailed models of gas turbines in electromechanical transient calculations. It is shown that the modern speed control systems of gas turbines in combination with relatively low equivalent inertia have a considerable effect on electromechanical transients, including those caused by disturbances not related to power imbalance.

The problem of disconnecting high-voltage cable lines with shunt reactors by SF₆ circuit breakers is discussed. In these schemes it is possible to have a significant aperiodic component of the circuit breaker current that can prevent opening of the breaker. The authors propose methods for application to cable transmission lines which they believe will be optimal for ensuring normal disconnects.

Results are considered for a study of basic power steel corrosion rate in a producer gas atmosphere and a method is proposed for its calculation under industrial conditions.

Acharacteristic feature of an electric power system (EPS) is a great number of possible states. Each state is described by a set of independent parameters representing reliability, stability, efficiency, etc. It is proposed to use a vector-valued objective function to assess a state for acceptability. The set of best states can be found using multi-objective optimization, which is considered as a method to make effective decisions.