DSpace Repository

Welcome to the NLR Reports Repository

Royal NLR conducts research, which is published in reports. Only a minor part of these reports is made public. This repository holds these public, so called Technical Publications (TP), mainly produced from 1996 up till now.

Technical publications published before 1996 may be obtained using the request-form. Other types of NLR-reports are Contract Reports (CR) and Technical Reports (TR), which in general are not public. You may however request a copy by using the request-form. In some cases permission may be granted, depending on specific properties and contractor of the report. Reports will be supplied as pdf-file.

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Recent Submissions

Using single pulses in powder-blown directed energy deposition to fabricate high-aspect-ratio metal pins
(Elsevier, 2026) Wits, W.W.; Yang, S.; Vroon, J.; Bremer, S.J.L.
This study investigates the fabrication of high-aspect-ratio metal pins using powder-blown directed energy deposition. Pins are deposited by consecutive laser pulses using titanium alloy Ti6Al4V as feedstock material. A physics-integrated experimental-analytical-numerical framework is developed to predict pin geometry, pin growth and thermal history during fabrication. The framework combines experimental in-situ temperature measurements, an analytical geometry model, and a finite element thermal model for melt pool lifetime predictions. Results show good agreement between model predictions and experimental observations, enabling controlled constant-diameter vertical pin growth with optimised process parameters, which is crucial for applications such as hybrid metal-composite joining and structural repair.
Enhanced Computational Performance and Stability & Control Prediction for NATO Military Vehicles
(AIAA, 2026) Stradtner, M.; Drazen, D.A.; Rooij, M.P.C. van
Numerical simulations are a principal tool across the lifecycle of NATO military air and sea vehicles. Traditional low-fidelity methods such as potential flow or Euler codes are often used in the early stages of the design cycle due to their lower computational cost and time requirements. However, these methods may lack the required accuracy for certain design scenarios, and the use of higher-fidelity methods such as computational fluid dynamics and experiments is often limited by the tremendous cost and timescales necessary for providing comprehensive data sets. A feasible means to overcome these limitations is reduced-order modeling. Over a four-year period the NATO Science & Technology Organization Research Task Group 351 of the Applied Vehicle Technology panel developed various data-driven reduced-order models. Those were applied on four different air and sea vehicle use cases, which demonstrated nearly real-time data set population and maneuver or course-keeping prediction capabilities. A summary of the Research Task Group is presented in terms of the air and sea use cases, methods, and results. Additional work is required to understand the real extent of cost reduction achievable with these approaches. Open questions remain on combining data sets with different fidelity levels or quantifying uncertainty in models.
The Role of Communication and Engagement in Airport Noise Management.
(MDPI, 2021) Heyes, G.H.; Hooper, P.H.; Raje, F.R.; Dimitriu, D.D.; Galatioto, F.G.; Burtea, N.E.B.; Ohlenforst, B.A.; Konovalova, O.K.
Research suggests that non-acoustic factors can have a considerable effect on community attitudes and opinions towards aviation noise and that these can be influenced through processes of communication and engagement. This paper reviews literature from various fields to identify the key elements of effective practice, using them as a lens through which to assess case study noise management actions conducted at European airports. This analysis found that communication and engagement holds significant potential for noise management, but that this remains largely unfulfilled due to such methods being used as an ancillary management activity, rather than as a powerful tool to aid in the design and delivery of noise management actions. A series of recommendations and research priorities are proposed that could shape the future of noise management, including potential changes to European policy that more explicitly advocate for communication and engagement as a noise management tool in its own right.
Main challenges and goals of the H2020 STRATOFLY project
(Springer, 2021) Viola, N.; Fusaro, R.; Saracoglu, B.; Schram, C.; Grewe, V.; Martinez, J.; Marini, M.; Hernandez, S.; Lammers, K.H.; Vincent, A.; Hauglustaine, D.; Liebhardt, B.; Linke, F.; Fureby, C.
As eluded in previous studies, with special reference to those carried out in the European framework, some innovative high-speed aircraft configurations have now the potential to assure an economically viable high-speed aircraft fleet. They make use of unexploited flight routes in the stratosphere, offering a solution to the presently congested flight paths while ensuring a minimum environmental impact in terms of emitted noise and green-house gasses, particularly during stratospheric cruise. Only a dedicated multi-disciplinary integrated design approach could realize this, by considering airframe architectures embedding the propulsion systems as well as meticulously integrating crucial subsystems. In this context, starting from an in-depth investigation of the current status of the activities, the STRATOFLY project has been funded by the European Commission, under the framework of Horizon 2020 plan, with the aim of assessing the potential of this type of high-speed transport vehicle to reach Technology Readiness Level (TRL) 6 by 2035, with respect to key technological, societal and economical aspects. Main issues are related to thermal and structural integrity, low-emissions combined propulsion cycles, subsystems design and integration, including smart energy management, environmental aspects impacting climate change, noise emissions and social acceptance, and economic viability accounting for safety and human factors. This paper aims at summarizing the main challenges and goals of the STRATOFLY project, highlighting the steps forward with respect to the past European Projects and underlying the next planned goals.
The Effectiveness of Blue-Light-Emitting Glasses in Security Guards Exposed to Night ShiftWork on Work-Related and General Fatigue: A Randomised Controlled Cross-Over Study
(MDPI, 2022) Helmhout, P.H.; Timmerman, S.; Drongelen, A. van; Bakker, E.W.P.
This study aimed to evaluate the effectiveness of glasses that emit blue light in reducing the need for recovery, general fatigue, and stress levels in security guards who work night shifts. Light manipulation is seen as a promising strategy to mitigate complaints related to shift work, such as sleepiness and impaired cognitive performance. In a randomized controlled cross-over study design, 86 Dutch security guards used light-emitting glasses (exposure duration: 30 min) during night shifts in a five week period versus a five week control period without glasses. Measurements (Need for Recovery Scale; Checklist Individual Strength; stress level assessed by a fitness tracker) were performed at baseline, at five weeks, and again at 11 weeks. The chronotype was measured at baseline as a potential covariate. A mixed model for repeated measure analyses showed no significant reduction in the need for recovery, nor a reduction in general fatigue scores, during the intervention period. Paired Samples T-Test analyses showed no significant changes in stress levels for the intervention period. Conclusively, blue light exposure using light-emitting glasses for security guards during night shifts showed no directly measurable effect on the reduced need for recovery, overall fatigue, and stress levels.