- document
-
Hemelaar, Senne (author)While the assumption of incompressible flow has been the prevailing standard for numerical simulations of wind turbine aerodynamics, the limit of this assumption is approached as the industry progresses towards increasingly higher operational tip speeds. This thesis explores the implications of compressibility and transonic flow phenomena,...master thesis 2024
- document
-
Schilder, Jop (author)Contrary to conventional wisdom favouring smooth surfaces for drag reduction, the last decades have brought forth different textured surfaces showing drag reduction in turbulent boundary layers, of which riblets are the most studied.<br/>Sirovich and Karlson (1997) introduced a different textured surface named chevron-shaped protrusions,...master thesis 2024
- document
-
PENG, Yi-Kai (author)Boundary Layer Ingestion (BLI) is a promising propulsion concept for aviation, aiming to reduce fuel burn. This configuration involves using the propulsor to ingest the boundary layer from the fuselage or wing. Typically, aircraft with BLI propulsors also integrate a hybrid-electric powertrain. This integrated setup has shown potential in fuel...master thesis 2023
- document
-
Jha, Mayanka (author)With ongoing research towards clean combustion, hydrogen has been identified as a potential alternative to natural gas fuel, for example in power generation sectors utilizing gas turbines because of their inherent nature of being a carbon-free energy carrier. However, it is crucial to clarify that the ultimate goal is not just carbon-free...master thesis 2023
- document
-
Janoff, Philipp (author)Leading edge roughness is an important challenge for the wind energy industry as blades are permanently exposed to the damaging impacts of the environment. The contamination due to impact of insects, ice accretion and dust; as well as the erosion of the blade due to rain, debris and abrasive airborne particles increase roughness upon the surface...master thesis 2023
- document
-
Budanko, Toma (author)An experimental investigation is presented in which an array of pulsed jet actuators is used to control a turbulent separation bubble formed on a curved backward facing ramp. The array is positioned upstream of detachment and consists of wall-normal high aspect ratio skewed rectangular jets which generate streamwise vortices in the boundary...master thesis 2023
- document
-
Kukučka, Tomas (author)Boundary Layer Ingestion (BLI) is a promising technology for reducing the impact of aviation on the environment. By placing a propulsor on an aircraft such that it ingests the slower moving air within the boundary layer, a decrease in power consumption can be achieved. Evaluating the performance of BLI configurations remains a challenge though....master thesis 2023
- document
-
Topper, Friso (author)Boundary layer ingestion is an airframe-propulsion integration technology capable of enhancing aircraft propulsive efficiency. The Propulsive Fuselage Concept, a tube-and-wing layout with an rear-fuselage-mounted propulsor in the boundary layer ingestion configuration, especially takes advantage this. However, the relation between physical shape...master thesis 2023
- document
-
Formidabile, Martina (author)TOP contoured nozzles, with large area-ratios, are commonly employed in rocket propulsion systems as they feature an excellent thrust-to-weight ratio. A significant shortcoming to this design is that, during the startup and shutdown transients of a LRE, the internal nozzle flow progresses through a series of overexpanded flow states - Free Shock...master thesis 2023
- document
-
Singh, Pratyush Kumar (author)In recent years, research for turbulent boundary layer (TBL) has shifted towards developing novel approaches to reduce drag. This shift is driven by new industrial standards emphasizing fuel-efficient and environmentally friendly air transportation. As wall-bounded turbulence plays a significant role in the overall drag experienced by an...master thesis 2023
- document
-
Jose, Nikhil (author)Surfaces that induce slip at the wall have been shown to reduce skin friction drag in the turbulent regime. While superhydrophobic and liquid-infused surfaces are capable of drag reduction in turbulent hydrodynamic flows, neither would be feasible in aerodynamic applications due to the added roughness and the minuscule slip lengths created by...master thesis 2023
- document
-
Makaveev, Momchil (author)This project proposes and evaluates a novel concept for an airspeed instrument aimed at small hybrid unmanned aerial vehicles. The working principle is to relate the power spectra of the wall-pressure fluctuations beneath the turbulent boundary layer formed over the vehicle’s body to its airspeed. The instrument consists of two microphones,...master thesis 2023
- document
-
Sequeira, Aaron (author)Laminar-to-turbulent boundary layer transition on the wings and stabilizers of aircraft leads to a large increase in the skin-friction drag they experience during flight. This has motivated prolific research into understanding and delaying the transition process, in an effort to improve the economic and ecological impact of air travel. The swept...master thesis 2022
- document
-
Molahalli, Pranav (author)Due to the global energy crisis, there is a growing need to make industrial processes more efficient and clean. One such method is to use effective and renewable working fluids in power and refrigeration cycles. Research in this field during the past decade has placed supercritical CO2 (SCO2) in the forefront due to its non-ideal properties and...master thesis 2022
- document
-
Raju, Darshan (author)The energy transition from fossil fuels to renewable energy sources is crucial for climate resilience. In particular, hydrogen combustion in gas turbine combustors is expected to play an essential role in the energy transition. Hence, a fuel-flexible gas turbine combustor operating with a wide range of natural gas and hydrogen fuels is necessary...master thesis 2022
- document
-
van der Laan, Fedor (author)Hydrogen is a promising fuel for both reducing greenhouse gas emissions and being used as an energy carrier for renewable energy sources. The adaption of hydrogen instead of natural gas as a fuel in gas turbine combustors introduces additional challenges regarding flame stability. One instabilities is boundary layer flashback. This phenomenon...master thesis 2022
- document
-
van de Krol, Bart (author)The most used RANS-model in relation to wind farms, k−epsilon, has significant shortcomings. It over-predicts the eddy viscosity in the near-wake and fails to model the anisotropy of the turbulence quantities. The Sparse Regression of the Turbulence Stress Anisotropy (SpaRTA) method could remedy these shortcomings. This method uses temporally...master thesis 2022
- document
-
Kramer, Zino (author)This research aims to analyse the non-ohmic resistance of multiple ion-exchange membranes (IEM) in series, for a better understanding of membrane resistances. These membranes can be found in series in energy storage systems such as acid-base flow batteries (ABFB).<br/>The effect of different current densities on the ohmic and non-ohmic...master thesis 2022
- document
-
Carrasco Grau, Julio (author)In the last decades, the prevailing belief that smooth surfaces offer the lowest drag has been challenged often. Scholars have, for example, introduced rough and modified surfaces to reduce turbulent skin friction. One of the technologies proposed in the literature is an array of chevron-shaped protrusions; however, there is no academic...master thesis 2022
- document
-
Kokkedee, Jop (author)With an ever increasing demand for sustainable energy, limitations of current sustainable technologies are studied widely. In wind farms, the so-called wake effect provides the biggest limitation on wind farm total power output. Using wind from the unaffected boundary layer to re-energize the wind flow in the wake provides a method of limiting...master thesis 2022