Experimental Study on Head Losses in the Sewer Pipe due to Manhole Shapes

Abstract

Rapid urbanization has caused complicated sewerage system as well as landscape of building structures. Since the major loss in the pipe is friction, it is possible to neglect energy losses while designing sewer systems with free surface flow, but under the pressurized condition, the energy losses may exceed the friction losses and reduce system capacity significantly, thus it is needed to consider the energy losses. Basically one-dimensional model is used to simulate sewerage system involving manholes and junctions with pipe configuration for calculating time and capacity efficiency although the head losses caused by manhole and pipe configuration are not one-dimensional (1D) phenomena. It causes problems that non 1D phenomena are artificially treated as one-dimensional. Therefore it is necessary to develop the model which can reflect the head losses depending on the pipe configuration and manhole shapes. In order to develop the simulation model, the fundamental laboratory experiments were conducted to estimate the effects of head loss depending on different manhole shapes with no benching and no invert. First, straight case experiments were conducted to evaluate the head loss for circular and square type manhole shape under the unsteady-state as well as steady-state condition and then numerical simulation model was developed and validated to confirm an applicability of the model using head loss coefficients obtained from laboratory experiments.