Ordinary Operating Conditions of Large Channels of Moscow's Sewerage Network

Abstract

The subject of investigation in this paper is large channels of an urban sewerage network. The analysis of dynamical properties of a sewer, as a component of the controlled system is performed in terms of automatic control theory. The analytic relationship of channel “3 dB frequency” as a function of its morphometric and operating mode parameters is obtained. An analysis of frequency characteristics, assuming that the water flow in large sewers is quasistatic, was carried out. The theoretical results were verified by means of flow depth variation curves surveyed in real situations of Moscow's sewerage network. Estimation of the maximal value of the rate of sewage depth change in sewers was performed by using graph-analytic techniques of applied spectral analysis. Results indicate that the amplitudes of the harmonic components of the sewage flow depth variations, greater than third, are no more than 10% of the value of the constant component. It was concluded that the hypothesis concerning the quasistatic operating conditions in large channels is reasonable for any practical length of time. This substantially simplifies the mathematical model of a channel and leads to sewerage network controlling algorithms that are more convenient for realization.