Large amounts of sediment in the Himalayan rivers causes severe silt erosion to the hydraulic machinery operating along these rivers. In this study, the effects of silt characteristics on the silt-erosion characteristics of a double-suction centrifugal pump was studied and the anti-erosion property of bionic convex domes on silt erosion under these conditions was explored by using computational-fluid-dynamics methods, partly supported by a painted-blade erosion experiment. The results show that the silt size affects the erosion position and erosion strength, whereas the silt concentration mainly affects the erosion strength for the studied range. The bionic convex domes provide an effective solution to improve the silt erosion for most of the investigated silt-laden conditions by decreasing the erosion rate and the erosion area of the blade. The anti-erosion mechanism was studied combined with large eddy simulation. The analysis shows that the relative velocity of water around the blade surface is changed and the mass flow rate of silt particles hitting the blade is reduced by inducing swirling flows around the bionic convex domes.

Erosion wear is a major problem for hydraulic turbines operating on rivers from the Himalaya Mountains. The runner is the most important energy conversion component but it suffers heavy damage due to direct contact with the sediment-laden water. In this research, the runner's physical erosion wear mechanism is revealed using numerical simulations and the results are compared with damaged runners from Francis turbines in the Jhimruk Hydroelectric Center (JHC). Simulations show that high erosive wear occurs near the blade outlet on the suction side, which is consistent with site observations. Because of the high relative velocity at the runner outlet, the high accretion rate appears to be directly responsible for the heavy erosion rate. The adjustment of the guide vanes is the main action available in real situation to change the operation condition of turbine and flow separation can easily occur under off-design conditions, causing interblade vortex production. The vortex guides particles to one location where they gather, producing high accretion rates and aggravating erosion wear. This implies that the interblade vortex is the main factor that induces severe erosive wear at the blade outlet. When the angle of the guide vanes is adjusted to provide the highest efficiency, the erosion rate can be greatly reduced.

Sediment erosion of hydraulic turbines is a significant challenge in hydropower plants in mountainous regions like the European Alps, the Andes, and the Himalayan region. The erosive wear of Pelton runner buckets is influenced by a variety of factors, including the size, hardness, and concentration of silt particles; the velocity of the flow and impingement angle of the jet; the properties of the base material; and the operating hours of the turbine. This research aims to identify the locations most susceptible to erosion and to elucidate the mechanisms of erosion propagation in two distinct designs of Pelton runner buckets. The Pelton runner buckets were subjected to static condition tests with particle sizes of 500 microns and a concentration of 14,000 mg/L. The buckets were coated with four layers of paint, sequentially applied in red, yellow, green, and blue. The two Pelton buckets, $D_1$ and $D_2$, were evaluated for their erosion resistance properties. $D_2$ demonstrated superior erosion resistance, attributed to its geometrical features and material composition, lower erosion rates, less material loss, and improved surface integrity compared with D1. This difference is primarily attributed to factors such as the splitter’s thickness, the jet’s impact angle, the velocity at which particles strike, and the concentration of sand. $D_2$ exhibits a great performance in terms of erosion resistance among the two designs. This study reveals that the angle of jet impingement influences erosion progression and material loss, which is important to consider during a Pelton turbine’s design and operating conditions.

Designing and manufacturing site-specific turbines for small hydropower is not economical. Using abundantly available Pump, from the market, as Turbine (PAT) instead of designing a completely different turbine can be much more economical for small-scale hydropower. Lot of research have been going throughout the world on this and has already proven its effectiveness. In Nepalese hydropower, including the ones already developed and the ones that will be developed in the future, Francis turbines are supposedly the suitable turbine of choice. However, designing and manufacturing Francis turbine is a tedious task and the local manufacturers, who are expert in manufacturing Cross-flow turbines; do not have the technology and competence to manufacture the modern Francis turbines. Sediment in Himalayan rivers are the major hurdles of operation as they reduce the lifetime of the turbine by a very large factor, shooting up the maintenance cost of the hydropower. The operational region of Francis turbine and PAT overlaps quite a lot, thus indicating that PAT can be used in many of the hydropower in Nepal. The Chinese and Indian pump manufacturers are already renowned in developing a wide range of pumps and supplying them in Nepal. Despite having such great opportunity, pumps have never been used in turbine mode in Nepalese hydropower. In addition to that, no research has been done, in Nepal, regarding the effects of sediment on pumps being operated as pump or turbine. This paper describes performance of pump in erosive environment using Computational Fluid Dynamics (CFD). It also compares the results obtained from the CFD analysis of sediment erosion in pump operated in pump mode as well as turbine mode with other researchers work. Finally, it compares the results obtained from the CFD with the results obtained from the experiment.

Francis turbine is the most widely used type of hydro turbine due to its high efficiency and a wide range of operation. Despite its popularity in large scale power plants, the use of these turbines has not been yet realized for micro hydro applications. Considering the sustainability of micro-hydro power plants, the components of Francis turbine need some simplifications so that the manufacturing and operation of the turbine become more feasible. This study focuses on redesigning the turbine with simplifications in spiral casing and distributor along with investigating its effects on the performance of runner using CFD. Bovet method is used to obtain meridional dimension of runner while Bladegen feature of ANSYS 15.0 is applied to obtain the runner domain. Optimum design of the runner is obtained by analyzing the effect of parameters like wrap angle, lean angle, blade’s beta angle distribution and energy distribution on the runner’s performance. The velocity at the runner inlet is very low for micro Francis turbine which increases the dimension of spiral casing so dimension of spiral casing is made small by adjusting guide vane and stay vanes. A comparative study of conventional and simplified design is made based on pressure and tangential velocity distributions along spiral casing and distributor as well as on the performance of turbine. It is observed that the required reaction ratio and flow conditions can be obtained by combining the stay vanes and guide vanes. In addition, the proportion of combination depends on the magnitude of reaction ratio. It is found that the combining the stay vane and guide vane gives better result in best efficiency point however at other loading condition efficiency is lower which is due to improper stagnation.

Hydro turbines are prone to failure and the detection of fault in turbine is essential to ensure the reliability of power plant. This study investigates vibrational signals in a fault-induced Francis turbine using an experimental test setup to identify the trends that could be helpful in diagnosis of turbine faults. By analyzing the vibrational signal, the study aims to correlate the turbine's dynamic behavior. Faults in the turbine have been introduced by adding masses to the blades, and the experimental tests are conducted under two different conditions: dry and wet testing conditions for both normal and faulty turbine blades. The turbine's operating condition is determined with the help of pressure, flow, and RPM sensors. The turbine's speed is varied using a variable frequency drive. For the acquisition of vibration signals, the NI-LabVIEW system is employed along with a uniaxial vibration sensor located at the turbine bearing. The obtained vibration data are analyzed using the Fast Fourier Transform (FFT) algorithm and wavelet transform algorithm to identify frequency-domain characteristics. While studying and comparing the fundamental frequency of the turbine shaft, it is found that turbine faults can either increase or decrease the amplitude of the resonant peak frequency of the system, but the amplitude at other frequencies remains almost unaffected.