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High-resolution turbofan intake flow characterization by automated stereoscopic-PIV in an industrial wind tunnel environment

Ujjaini Kempaiah, K. (author), Piovesan, Tommaso (author), Zachos, Pavlos K. (author), Michaelis, Dirk (author), Gebbink, Roy (author), van Rooijen, Bart (author), Prieto, Daniel Gil (author), MacManus, David (author), Sciacchitano, A. (author), Sheaf, Christopher (author)

Unsteady inlet flow distortion can influence the stability and performance of any propulsion system, in particular for more novel, short and slim intakes of future aero-engine configurations. As such, the requirement for measurement methods able to provide high spatial resolution data is important to aid the understanding of these flow fields...

journal article 2024

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Including the effect of depth-uniform ambient currents on waves in a non-hydrostatic wave-flow model

Rijnsdorp, D.P. (author), van Rooijen, Arnold (author), Reniers, A.J.H.M. (author), Tissier, M.F.S. (author), de Wit, F.P. (author), Zijlema, Marcel (author)

Currents can affect the evolution of waves in nearshore regions through altering their wavenumber and amplitude. Including the effect of ambient currents (e.g., tidal and wind-driven) on waves in phase-resolving wave models is not straightforward as it requires appropriate boundary conditions in combination with a large domain size and long...

journal article 2023

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The impact of loose-parts-play on schoolyard social participation of children with and without disabilities: A case study

Eichengreen, Adva (author), van Rooijen, Martin (author), van Klaveren, Lisa Maria (author), Nasri, Maedeh (author), Tsou, Yung Ting (author), Koutamanis, A. (author), Baratchi, Mitra (author), Rieffe, Carolien (author)

Background: Outdoor social participation in the school playground is crucial for children's socio-emotional and cognitive development. Yet, many children with disabilities in mainstream educational settings are not socially included within their peer group. We examined whether loose-parts-play (LPP), a common and cost-effective intervention...

journal article 2023

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Interfacial Tensions, Solubilities, and Transport Properties of the H₂/H₂O/NaCl System: A Molecular Simulation Study

van Rooijen, W.A. (author), Habibi, P. (author), Xu, K. (author), Dey, P. (author), Vlugt, T.J.H. (author), Hajibeygi, H. (author), Moultos, O. (author)

Data for several key thermodynamic and transport properties needed for technologies using hydrogen (H₂), such as underground H₂ storage and H₂O electrolysis are scarce or completely missing. Force field-based Molecular Dynamics (MD) and Continuous Fractional Component Monte Carlo (CFCMC) simulations are...

journal article 2023

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Electrically Small High Permittivity Lens Antenna Using Artificially Loaded Thermoplastics at 170 GHz

van Rooijen, N. (author), Alonso Del Pino, M. (author), Bueno Lopez, J. (author), Spirito, M. (author), Llombart, Nuria (author)

This contribution presents the development of an electrically small lens antenna using an artificially loaded thermoplastic at 140-170GHz. We will present the on-going development of the Fly’s Eye front end antenna concept that was presented in [1]. The antenna is composed on a dual plastic lens, a core lens and a shell lens, fed by a double...

conference paper 2023

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W-Band Demonstration of Dynamic, High-Gain Beam Steering with a Scanning Lens Phased Array

Bosma, S. (author), van Rooijen, N. (author), Alonso Del Pino, M. (author), Spirito, M. (author), Llombart, Nuria (author)

We report the measured results of a sparse, 4x1 scanning lens phased array prototype at W-band that is capable of beam steering a directive (>30 dBi) beam towards ±20° with sidelobe levels around -10 dB. The array elements are high-aperture-efficiency resonant leaky-wave lens antennas with a feed that suppresses the spurious TM0 mode over a...

conference paper 2022

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A Wideband Leaky-Wave Lens Antenna with Annular Corrugations in the Ground Plane

Bosma, S. (author), van Rooijen, N. (author), Alonso Del Pino, M. (author), Llombart, Nuria (author)

We present a resonant leaky-wave lens antenna, fed by a circular waveguide with annular corrugations in the ground plane. The proposed leaky-wave feed reduces the impact of the spurious TM0 leaky-wave mode in all planes over a wide bandwidth while reducing assembly complexity compared to previous methods. The proposed leaky-wave antenna has...

journal article 2022

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Core-Shell Leaky-Wave Lens Antenna for 150GHz Fly’s Eye Communication Systems

van Rooijen, N. (author), Alonso Del Pino, M. (author), Spirito, M. (author), Llombart, Nuria (author)

This work presents a novel lens antenna architecture based on a core-shell lens design with a leaky-wave in-packaged antenna at 150GHz. An electrically small core lens made of dense dielectric material is used to enhance the radiation of the in-packaged antenna. A low-loss dielectric shell lens with electrically large dimensions is then added to...

conference paper 2022

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First Demonstration of Dynamic High-Gain Beam Steering With a Scanning Lens Phased Array

Bosma, S. (author), van Rooijen, N. (author), Alonso Del Pino, M. (author), Spirito, M. (author), Llombart, Nuria (author)

We report on the first demonstration of dynamic beam steering using a scanning lens phased array. A scanning lens phased array relies on a combination of mechanical and electrical phase shifting to dynamically steer a high-gain beam beyond the grating-lobe free region using a sparse array. These two concepts have been demonstrated separately in...

journal article 2022

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Microfluidics-based analysis of dynamic contact angles relevant for underground hydrogen storage

van Rooijen, W.A. (author), Hashemi, L. (author), Boon, M.M. (author), Farajzadeh, R. (author), Hajibeygi, H. (author)

Underground Hydrogen Storage (UHS) is an attractive technology for large-scale (TWh) renewable energy storage. To ensure the safety and efficiency of the UHS, it is crucial to quantify the H₂ interactions with the reservoir fluids and rocks across scales, including the micro scale. This paper reports the experimental measurements...

journal article 2022

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Wave transmission and drag coefficients through dense cylinder arrays: Implications for designing structures for mangrove restoration

Gijón Mancheño, A. (author), Jansen, W. (author), Uijttewaal, W.S.J. (author), Reniers, A.J.H.M. (author), van Rooijen, A. A. (author), Suzuki, T. (author), Etminan, V. (author), Winterwerp, J.C. (author)

Mangrove vegetation constitutes a natural coastal defence against waves and erosion. Despite their protective role, mangrove ecosystems have experienced continuous degradation over the last decades due to human causes. At retreating mangrove coastlines, bamboo structures are built to create new habitat for mangrove colonization. Existing...

journal article 2021

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High Aperture Efficiency Plastic Lens Antenna for Scanning Lens Phased Array at 180 GHz

Bosma, S. (author), van Rooijen, N. (author), Alonso Del Pino, M. (author), Llombart, Nuria (author)

In this contribution, we present a plastic resonant leaky-wave lens antenna with high aperture efficiency (>80%) over a 1:2 bandwidth centered at 180 GHz. This antenna can be integrated in a scanning lens phased array architecture for next-generation wireless and sensing applications that require high-directivity steerable beams. The high...

conference paper 2021

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Toward individual-sensitive automation for air traffic control using convolutional neural networks

van Rooijen, S. J. (author), Ellerbroek, Joost (author), Borst, C. (author), van Kampen, E. (author)

Lack of trust and lack of acceptance caused by strategic mismatches in problem-solving have been identified as obstacles in the introduction of workload-alleviating automation in air traffic control. One possible way to overcome these obstacles is by creating automation capable of providing personalized advisories conformal to the individual...

journal article 2020

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The Effect of Small Density Differences at River Confluences

van Rooijen, Erik (author), Mosselman, E. (author), Sloff, C.J. (author), Uijttewaal, W.S.J. (author)

Remarkable 3D flow structures occur at river confluences with small density differences due to differences in sediment concentration or temperature. We explain these by comparing numerical simulations for an idealized confluence with aerial photographs of several river confluences where color differences express the pattern of density...

journal article 2020

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Soap bubbles for large-scale PIV in industrial wind tunnels

Engler Faleiros, D. (author), Tuinstra, Marthijn (author), van Rooijen, Bart D. (author), Scarano, F. (author), Sciacchitano, A. (author)

This work evaluates the use of helium-filled soap bubbles (HFSB) for Particle Image Velocimetry (PIV) measurements at high Reynolds numbers (up to 3.2 million) in aeronautics. The measurements are performed in the Low Speed Tunnel (LST) of the German-Dutch Wind Tunnels (DNW) using a high-lift airfoil in close-to-stall conditions up to 70 m/s....

conference paper 2019

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Conformal automation for air traffic control using convolutional neural networks

van Rooijen, S. J. (author), Ellerbroek, Joost (author), Borst, C. (author), van Kampen, E. (author)

Lack of trust has been identified as an obstacle in the introduction of workload-alleviating automation in air traffic control. The work presented in this paper describes a concept to generate individual-sensitive resolution advisories for air traffic conflicts, with the aim of increasing acceptance by adapting advisories to different...

conference paper 2019

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Quantitative flow visualization of a turboprop aircraft by robotic volumetric velocimetry

Sciacchitano, A. (author), Giaquinta, Daniele (author), Schneiders, J.F.G. (author), Scarano, F. (author), van Rooijen, B.D. (author), Funes, D.E. (author)

The flow field around a turboprop aircraft scaled model is investigated with attention to the propeller slipstream and the wing near wake. The experiments are conducted in the Low-Speed Tunnel (LST) of the German-Dutch Wind Tunnels (DNW) as part of a collaboration among DNW, Delft University of Technology and Airbus. Quantitative flow...

conference paper 2018

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The effect of small density differences at large confluences

van Rooijen, E.J. (author), Mosselman, E. (author), Sloff, C.J. (author), Uijttewaal, W.S.J. (author)

Confluences are fascinating elements in river systems. The merging of tributary rivers produces complex hydrodynamics that can play an important role in sediment transport problems, ecological studies or the routing of a pollutant. If the two merging rivers originate from different regions they can have different characteristics. One such a...

abstract 2017

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Integration of a layer picking area with the OptilogX Sequencing Buffer - Integratie van een pallet-ombouwgebied met de OptilogX Sequencing Buffer

van Rooijen, K.E. (author)

master thesis 2016

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Identification and classification of very low frequency waves on a coral reef flat

Gawehn, M. (author), van Dongeren, AR (author), van Rooijen, A.A. (author), Storlazzi, C.D. (author), Cheriton, O.M. (author), Reniers, A.J.H.M. (author)

Very low frequency (VLF, 0.001–0.005 Hz) waves are important drivers of flooding of low-lying coral reef-islands. In particular, VLF wave resonance is known to drive large wave runup and subsequent overwash. Using a 5 month data set of water levels and waves collected along a cross-reef transect on Roi-Namur Island in the Republic of the...

journal article 2016