Bjørn Winther Solemslie

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• PhD
• Researcher at Norwegian Institute for Nature Research

The Pelton turbine has been subject to a varying degree of research interest since the debut of the technology over a century ago. Despite its age there are gaps in the knowledge concerning the flow mechanisms effecting the flow through the turbine. A Pelton turbine has been designed at the Waterpower Laboratory at NTNU. This has been done in conne...

An analysis of the pressure in a runner channel of a low-specific speed Francis model runner during resonance is presented, which includes experiments and the development of a pressure model to estimate both the convective and acoustic pressure field from the measurements. e pressure was measured with four pressure sensors mounted in the runner hub...

Over the last years, there have been several incidents with cracks in high head Francis turbines. These cracks are understood to be related to pressure pulsations, vibration modulus and the combination of these. In this paper, a setup for the investigation of pressure pulsations ina low specific speedmodel turbine is presented with the use of onboa...

A hydrofoil resembling a high head Francis runner blade was submerged in a rectangular channel and attached to the walls in a fixed-beam configuration. The hydrofoil was excited by piezoelectric Macrofiber composite actuators (MFCs), and the vibration was measured at the trailing edge with Laser Doppler Vibrometry (LDV) and semiconductor strain gau...

As Francis turbines are chasing a higher efficiency, while trying to accommodate a wider load region, turbine blade fatigue is becoming a more pronounced problem. Details of the Fluid-Structure Interaction (FSI) between the turbine blades and the passing water is necessary to accurately predict the dynamic behavior of a runner in the design phase....

A test rig has been developed at the Waterpower Laboratory of the Norwegian University of Science and Technology to conduct an in-depth investigation of flow-related phenomena and fluid-structure interaction, with the focus towards hydrodynamic damping, for a circular hydrofoil cascade configuration. The rig’s design enables the analysis of hydrody...

Downstream hydropower plants, a change in water chemistry can lead to the occurrence of a widely unknown problem: total dissolved gas (TDG) supersaturation. It takes place when air is entrained in a water body and exposed to high pressures, which leads to gas dissolution in the water. Re-exposure to atmospheric pressure downstream the power plant r...

In order to succeed in the transition to a more renewable energy sector, the hydropower industry must overcome multiple challenges in the coming decades, including the need for faster and reversible turbines to support emerging renewable energy sources. In addition, the location of new projects in tropical and semi-tropical areas poses unique consi...

Artificial total dissolved gas (TDG) supersaturation is a potentially lethal threat to the aquatic ecology downstream of hydropower plants. The severity of this threat dependents on the actual saturation level as well as on the duration of the event. Natural degassing is highly influenced by the river’s morphology and characteristics, and is in mos...

As the world transitions towards more renewable energy sources, as a step to reduce the emissions of CO 2 , intermittent and non-dispatchable sources like solar and wind will take up a larger proportion of the energy production. With more unregulated power in the energy mix, a higher demand is put on the rest of the energy production system. Hydrop...

In Norway, a recent project used a risk matrix to identify about 200 hydropower plants ( 11 % of the total number) of being in high risk of producing air-supersaturated water. The combined installed capacity of these hydropower plants amounts to more than 45 % of Norway’s total installed hydropower capacity. Total dissolved gas (TDG) supersaturatio...

Pelton turbine is an impulse turbine that converts kinetic energy of incoming jet of water into mechanical energy. Due to impingement of high-speed jet on buckets, Pelton turbine experience high stress at the tip of bucket and at the connection of bucket and rim. To provide the structural strength to the runner, a hoop is attached to it which allow...

Energy is the vital requirements of daily life. It is mainly concerned with production, storage, balance and distribution. Hydropower is a key sources of renewable energy. Regarding the storage of hydropower energy, pumped storage comes in the foremost choice. The runner is the main component of pump storage hydropower project. As the energy storag...

Prevention of greenhouse emissions is the top priority for all countries, which urges them to switch to renewable energy as much as possible. Hydropower is one of the renewables that have high flexibility and at the same time compatibility to be used with any other renewable sources. Moreover, hydropower plants operating in the Himalayas, Andes, an...

In this paper, we present the calibration setup, method, and results for a set of strain gauges installed on the trailing edge of the runner blades of a model Francis turbine. The calibration work is done as a step in the HydroFlex project, with the goal of taking experimental data to validate numerical models to better estimate the reduction in li...

In this work, the complex structural response of the Francis-99 turbine runner is further investigated by decomposition of the output signal from previous Laser Doppler Vibrometry (LDV) measurements into the motion of each nodal diameter. During the structural measurements, the non-rotating runner was installed in the turbine pit, submerged in a no...

The use of Computational Fluid Dynamics (CFD) for predicting the flow behaviour in Pelton turbines is limited by the complex nature of the flow, interaction between the jets and interference of the water after the impact on the buckets. Besides, validation of the numerical results in such turbines is usually challenging due to the unsteadiness of t...

The Francis-99 low specific speed Francis runner has undergone much study in the years since it was first made available to the public. The High Head Francis(HiFrancis) project, hosted by the Waterpower Laboratory at NTNU, have conducted multiple experimental campaigns to supply validation data for numerical simulations of the RSI phenomenon for th...

Hydropower is facing new operational strategies as the increasingly competitive power market demands for higher flexibility. Consequently, turbines are forced to handle tougher operation and are prone to more frequent degradation. By implementing a real-time monitoring system, a better understanding of the behavior of components may contribute to d...

In Norway, more than 10 hydropower plants are known to have caused biologically relevant levels of total dissolved gas supersaturation in the rivers downstream power plants. This phenomenon is causing fish kills due to gas bubble disease and have large impacts onthe biodiversity. The gas supersaturation is often caused by undersized or blocked broo...

Impulse turbines are widely used in hydropower plants around the world due to their high efficiency in a larger operating range compared to reaction turbines. State of the art Pelton turbines can give over 90% efficiency at the designed operation load. However, there lies a possibility of improving the efficiency at off design condition for these t...

Over the last years, several breakdowns in hydropower plants with low specific speed Francis runners have been reported. One of the main excitation forces in such runners is the pressure fluctuations originating from the rotor stator interaction. In this paper, the rotor-stator interaction has been analyzed utilizing pressure sensors onboard the ru...

Control valves, nozzles and other mechanical flow constricting constructions often introduces highly turbulent flow downstream of vena contracta. When solid particles are present in the fluid stream erosion can occur due to the high fluid velocity and turbulence, both in the converging and diverging section of a constriction. This paper presents an...

Due to thinner blades and higher demands for flexibility, the high-head Francis runners designed today face considerable challenges that severely affect the runners’ expected lifetime. For many high-head Francis runners, the leading cause of fatigue is blade cracking due to Rotor-Stator Interaction, which cause vibrations in the runner blades. Accu...

The Norwegian power system today includes a relatively large percentage of Francis turbines with a head of above 300m, in the world. This leads to a need to maintain and develop the national competence regarding the challenges connected to this type of turbine. The importance of this competence is increased by the fact that these turbines have a hi...

The rotor stator interaction in a low specific speed Francis model turbine and a pump-turbine is analyzed utilizing pressure sensors in the vaneless space and in the guide vane cascade. The measurements are analyzed relative to the runner angular position by utilizing an absolute encoder mounted on the shaft end. From the literature, the pressure i...

A post processing method has been developed to enable the extraction of quantifiable data from images captured from within the rotating frame of reference of a Pelton turbine. The turbine tested was the reference Pelton runner, designed at the Waterpower Laboratory (NTNU). The method relies on interpolation to 3D map the inner hydraulic surface of...

To enable a detailed study the flow mechanisms effecting the flow within the reference Pelton runner designed at the Waterpower Laboratory (NTNU) a flow visualization system has been developed. The system enables high speed filming of the hydraulic surface of a single bucket in the rotating frame of reference. It is built with an angular borescopes...

The Pelton turbine is a widely used technology for power generation first pat- ented in 1880. Despite being a mature technology, there is still little published knowledge regarding the design method of Pelton turbines. There is need of a common and accessible Pelton turbine geometry as a basis for future research. The chaotic environment surroundin...

A reference Pelton turbine developed at the Waterpower Laboratory at the Norwegian University of Science and Technology has been tested with different nozzle positions. The positions were the same in the radial direction, but had two different degrees of width-wise misalignment, leading to a difference in the jet area interacting with each side of...

The designs of hydraulic turbines are usually close kept corporation secrets. Therefore, the possibility of innovation and co-operation between different academic institutions regarding a specific turbine geometry is difficult. A Ph.D.-project at the Waterpower Laboratory, NTNU, aim to design several model Pelton turbines where all measurements, si...