Adaptation of an Existing Intake Structure Caused by Increased Sediment Level

Abstract

An unexpected and massive redistribution of fine sediment in a large Alpine reservoir was triggered by a further lowering of the water level to conduct maintenance work. This caused the need of a total redesign of the existing head race intake for a high head power plant in the Austrian Alps. Two main geometry options for the trash rack support structure are compared with numerical simulations (ANSYS-CFX) as well as with a scale model test (scale 1:20). The laboratory experiment substantially benefited from the preliminary numerical investigation in respect of the location and implementation of the model boundaries. In return was the confidence in the numerics strengthened by the successful validation of the local head loss and the velocity distribution for the main operation cases. This allowed that the main inputs for the structural design and the further optimisation is conducted only with the 3D-numerical tool. The paper presents the interlaced concept as well as the main finding of the investigation, which lead to a successful adaptation of the intake structure.

Experimental Hydraulic Investigation of Angled Fish Protection Systems—Comparison of Circular Bars and Cables

“…If the individual measured values are averaged for each measurement (Figure 4, right), it can be seen that the single outliers do not have such a significant influence on the mean value. Nevertheless, the previous comparison highlights the importance of the DPT to measure the differential pressure ∆p DPT with a very high accuracy, as known from previous studies [15,19]. The DPT was further chosen as input values for the ξ-calculation based on Equation (4).…”

“…It was assumed that the velocity distribution over the complete cross section is homogeneous. For some applications and under specific circumstances, the velocity of the complete cross section of the trash rack can change significantly, which could be part of future investigations [19]. For the presented results, the velocity v 1 was used as v re f , hence this is a section that is in most cases easily accessible and does not include the influence of the trash rack (Section 3.2).…”

Numerical Study of Sediment Erosion Analysis in Francis Turbine

“…The turbine components damage by the erosion has remained a significant provocation in hydropower establishment; multiple complex factors affect this damage process, such as blade geometry and material, flow conditions, the particle shape, hardness, traveling velocity, and the duration of the effect developed by the particles [9]. Various techniques have been investigated and examined to minimize sediment erosion-related problems [10][11][12], including prevention of sedimentation in catchment areas [12,13], management of reservoir sedimentation and sediment transport [14,15], tapping sediments at intakes [16,17], and applying preventive coating techniques on the hydraulic turbine components and damage caused by ingestion of external bodies in hydraulic turbines [18,19]. Therefore, to avoid sediment erosion, it is essential to be capable of accurate prediction of the behavior of erosion and know where it is possibility to happen.…”

Short-Term Load Dispatching Method for a Diversion Hydropower Plant with Multiple Turbines in One Tunnel Using a Two-Stage Model

“…where h f is the frictional head loss, m; λ is frictional head loss coefficient; l is the length of the tunnel, m; R is hydraulic radius, m; v is flow velocity, m/s; and g is the gravity acceleration, m/s. The local head loss [30][31][32] can be calculated by Equation 2:…”