Refine
Year of publication
Institute
- Fachbereich Bauingenieurwesen (664) (remove)
Has Fulltext
- no (664) (remove)
Document Type
- Article (327)
- Book (117)
- Conference Proceeding (103)
- Part of a Book (86)
- Report (17)
- Doctoral Thesis (6)
- Contribution to a Periodical (2)
- Patent (2)
- Working Paper (2)
- Conference Poster (1)
Keywords
- metal structure (4)
- steel (4)
- industrial research (3)
- iron and steel industry (3)
- materials technology (3)
- research report (3)
- Architektur (2)
- Deutschland (2)
- Haustechnik (2)
- Heizung (2)
- Klimatechnik (2)
- Lüftung (2)
- Lüftungstechnik (2)
- Stickstoffoxide (2)
- Wasserbau (2)
- Wasserwirtschaft (2)
- building industry (2)
- building information modelling (2)
- building materials (2)
- energy efficiency (2)
- research project (2)
- resistance of materials (2)
- 20 fossil-fueled power plants (1)
- 3D printing (1)
- Abluft (1)
- Anschlüsse an Stahlbeton (1)
- BIM (1)
- Behälterbau (1)
- Bemessung (1)
- Brandfall (1)
- Brandschutz (1)
- Brückenbau (1)
- Didaktik (1)
- Druckvergasung (1)
- Druckwirbelschichtfeuerung (1)
- EN 1993-1-2 (1)
- Eingespannte Stützen und Träger (1)
- Einspanntiefen (1)
- Energy system (1)
- Entstaubung (1)
- Festigkeitslehre (1)
- Filter (Stofftrennung) (1)
- Filterkuchen (1)
- Filtration (1)
- Forschung, pränormativ (1)
- Freshmen (1)
- Geotechnik (1)
- HVAC (1)
- Hazard assessment (1)
- Heterogene Katalyse (1)
- Hydraulic structures (1)
- Kohlefeuerung (1)
- Kohlenmonoxidbelastung (1)
- Kraftwerkstechnik (1)
- Landslide tsunamis (1)
- Large scale tests (1)
- Mischen (1)
- Mixed integer linear programming (MILP) (1)
- Nasskühlturm (1)
- Open channels (1)
- Overland flow (1)
- PIV (1)
- Physical modeling (1)
- Proper Orthogonal Decomposition (1)
- Prozesssimulation (1)
- Q-criterion (1)
- Rauchgasreinigung (1)
- Reduktion <Chemie> (1)
- Renewable energy (1)
- Rohrreaktor (1)
- Schadgas (1)
- Sharing mobility (1)
- Similitude (1)
- Smart Building Engineering (1)
- Solitary waves (1)
- Stahlprofile (1)
- Staubfilter (1)
- Time-series aggregation (1)
- Tragwerksbemessung (1)
- Trockenkühlturm (1)
- Typical periods (1)
- VOF (1)
- Wirbelschichtfeuerung (1)
- anammox (1)
- building safety (1)
- building technique (1)
- business models (1)
- ceramics (1)
- coherent structures (1)
- construction (1)
- dam-break (1)
- designs and models (1)
- digital teaching (1)
- digitale Lehre (1)
- drag force (1)
- electro mobility (1)
- emote practical training (1)
- energy disspation (1)
- filtration (1)
- food production (1)
- friction (1)
- gas flow (1)
- geotechnical engineering (1)
- guide (1)
- hot gas cleanup (1)
- hydraulic modelling (1)
- ingot (1)
- keramischer Werkstoff (1)
- kombiniertes Verfahren (1)
- lockdown conditions (1)
- mainstream deammonification (1)
- mobility behaviour (1)
- model performance (1)
- nitrogen elimination (1)
- numerical model (1)
- physical model (1)
- prefabrication (1)
- remote teamwork (1)
- renewable energy (1)
- roleplay (1)
- small and medium scaled companies (1)
- smart building engineering (1)
- smart engineering (1)
- steel profiles (1)
- structural design (1)
- sustainability (1)
- testing (1)
- thermal insulation (1)
- urban farming (1)
- virtual reality (1)
- wastewater (1)
- wave run-up (1)
This thesis aims at the presentation and discussion of well-accepted and new
imaging techniques applied to different types of flow in common hydraulic
engineering environments. All studies are conducted in laboratory conditions and
focus on flow depth and velocity measurements. Investigated flows cover a wide
range of complexity, e.g. propagation of waves, dam-break flows, slightly and fully
aerated spillway flows as well as highly turbulent hydraulic jumps.
Newimagingmethods are compared to different types of sensorswhich are frequently
employed in contemporary laboratory studies. This classical instrumentation as well
as the general concept of hydraulic modeling is introduced to give an overview on
experimental methods.
Flow depths are commonly measured by means of ultrasonic sensors, also known as
acoustic displacement sensors. These sensors may provide accurate data with high
sample rates in case of simple flow conditions, e.g. low-turbulent clear water flows.
However, with increasing turbulence, higher uncertainty must be considered.
Moreover, ultrasonic sensors can provide point data only, while the relatively large
acoustic beam footprint may lead to another source of uncertainty in case of
relatively short, highly turbulent surface fluctuations (ripples) or free-surface
air-water flows. Analysis of turbulent length and time scales of surface fluctuations
from point measurements is also difficult. Imaging techniques with different
dimensionality, however, may close this gap. It is shown in this thesis that edge
detection methods (known from computer vision) may be used for two-dimensional
free-surface extraction (i.e. from images taken through transparant sidewalls in
laboratory flumes). Another opportunity in hydraulic laboratory studies comes with
the application of stereo vision. Low-cost RGB-D sensors can be used to gather
instantaneous, three-dimensional free-surface elevations, even in flows with very
high complexity (e.g. aerated hydraulic jumps). It will be shown that the uncertainty
of these methods is of similar order as for classical instruments.
Particle Image Velocimetry (PIV) is a well-accepted and widespread imaging
technique for velocity determination in laboratory conditions. In combination with
high-speed cameras, PIV can give time-resolved velocity fields in 2D/3D or even as
volumetric flow fields. PIV is based on a cross-correlation technique applied to small
subimages of seeded flows. The minimum size of these subimages defines the
maximum spatial resolution of resulting velocity fields. A derivative of PIV for
aerated flows is also available, i.e. the so-called Bubble Image Velocimetry (BIV). This
thesis emphasizes the capacities and limitations of both methods, using relatively
simple setups with halogen and LED illuminations. It will be demonstrated that
PIV/BIV images may also be processed by means of Optical Flow (OF) techniques.
OF is another method originating from the computer vision discipline, based on the
assumption of image brightness conservation within a sequence of images. The
Horn-Schunck approach, which has been first employed to hydraulic engineering
problems in the studies presented herein, yields dense velocity fields, i.e. pixelwise
velocity data. As discussed hereinafter, the accuracy of OF competes well with PIV
for clear-water flows and even improves results (compared to BIV) for aerated flow
conditions. In order to independently benchmark the OF approach, synthetic images
with defined turbulence intensitiy are used.
Computer vision offers new opportunities that may help to improve the
understanding of fluid mechanics and fluid-structure interactions in laboratory
investigations. In prototype environments, it can be employed for obstacle detection
(e.g. identification of potential fish migration corridors) and recognition (e.g. fish
species for monitoring in a fishway) or surface reconstruction (e.g. inspection of
hydraulic structures). It can thus be expected that applications to hydraulic
engineering problems will develop rapidly in near future. Current methods have not
been developed for fluids in motion. Systematic future developments are needed to
improve the results in such difficult conditions.
Energy saving ordinances requires that buildings must be designed in such a way that the heat transfer surface including the joints is permanently air impermeable. The prefabricated roof and wall panels in lightweight steel constructions are airtight in the area of the steel covering layers. The sealing of the panel joints contributes to fulfil the comprehensive requirements for an airtight building envelope. To improve the airtightness of steel sandwich panels, additional sealing tapes can be installed in the panel joint. The influence of these sealing tapes was evaluated by measurements carried out by the RWTH Aachen University - Sustainable Metal Building Envelopes. Different installation situations were evaluated by carrying out airtightness tests for different joint distances. In addition, the influence on the heat transfer coefficient was also evaluated using the Finite Element Method (FEM). The combination of obtained air volume flow and transmission losses enables to create an "effective heat transfer coefficient" due to transmission and infiltration. This summarizes both effects in one value and is particularly helpful for approximate calculations on energy efficiency.
Since several decades, dam-break waves have been of main research interest. Mathematical approaches have been developed by analytical, physical and numerical models within the past 120 years. During the past 10 years, the number of research investigations has increased due to improved measurement techniques as well as significantly increased computer memories and performances. In this context, the present research deals with the initial stage of two-dimensional dam-break waves by comparing physical and numerical model results as well as analytical approaches. High-speed images and resulting particle image velocimetry calculations are thereby compared with the numerical volume-of-fluid (VOF) method, included in the commercial code FLOW-3D. Wave profiles and drag forces on placed obstacles are analysed in detail. Generally, a good agreement between the laboratory and VOF results is found.