scholarly journals Assessment of downward draught in high-glazing facades in cold climates – experimental and CFD study into draught control with a 21-type radiator

2021 ◽  
Vol 246 ◽  
pp. 02002
Author(s):  
Karl-Villem Võsa ◽  
Andrea Ferrantelli ◽  
Jarek Kurnitski
Keyword(s):  
Cfd Simulation ◽  
Standardized Test ◽  
Test Chamber ◽  
Thermal Plume ◽  
Cold Climates ◽  
Experimental Phase ◽  
High Fraction ◽  
Typical Solution ◽  
Partial Loads ◽  
Insight Into

This paper investigates the interaction of a radiator’s thermal plume and downdraught of cold glazed surfaces. Draughts in working areas are one of the most common thermal comfort complaints in modern buildings. A typical solution for dealing with these draughts is positioning the heat emitters such as radiators or convectors under the windows. However, with thermally efficient envelopes, the internal loads compromise a relatively high fraction of the heating demand and the emitters are working under partial loads in modern buildings. This study comprises two parts: an experimental phase in the EN442 standardized test chamber with a 21-type radiator, and a CFD simulation phase, where the model is validated and applied under an expanded set of boundary conditions. The expanded simulation set results provide preliminary insight into sizing and design. More specifically, the thermal plume can be parametrised with a velocity and temperature value along with the room air and glazing temperatures for a broader analysis and assessment of the risk of draught.

On the Effectiveness of Baffles in Indirect Solar Storage Systems

2007 ◽  
Vol 129 (4) ◽  
pp. 494-498 ◽  
Author(s):  
F. A. Kulacki ◽  
Jane H. Davidson ◽  
M. Hebert
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Storage Systems ◽  
Boundary Layer Theory ◽  
Base Case ◽  
Thermal Plume ◽  
Storage Tanks ◽  
Physical Mechanisms ◽  
Design Factors ◽  
Insight Into

Parameters that control heat transfer and mixing in energy extraction from indirect solar storage tanks that employ an immersed heat exchanger with a straight baffle beneath are identified and estimated. The analysis of flow in the baffle is based on boundary layer theory and provides insight into the effectiveness of a baffle in controlling growth of the thermal plume from the heat exchanger. The important physical mechanisms are the restricted entrainment and heat transfer to the storage fluid. For an adiabatic baffle as a base case, key design factors are the point of attachment of the plume on the baffle and the width of the baffle relative to that of the heat exchanger.

scholarly journals Design of short low speed Göttingen type wind tunnel: CFD simulation

2018 ◽  
Vol 145 ◽  
pp. 03015
Author(s):  
Hardy Weisweiler ◽  
Jasmina Kojouharova ◽  
Roland Dückershoff
Keyword(s):  
Applied Sciences ◽  
Wind Tunnel ◽  
Test Section ◽  
Cfd Simulation ◽  
Test Chamber ◽  
Sectional Area ◽  
Cross Sectional ◽  
Low Speed ◽  
University Of Applied Sciences ◽  
Open Test

The paper is focused on design simulations by the means of commercial software for a low speed circuit wind tunnel with an open test section, recently built at the Department of Mechanical Engineering, Mechatronics and Materials Technology at THM University of Applied Sciences in Friedberg. The proposed wind tunnel has a test section with cross sectional area of 1 X 1 m2 and a length of 1.6 m. The maximum achievable speed is about 50 m/s with empty test section. The simulation had the target to propose and to verify various geometries - test chamber, tunnel contraction, diffuser etc. as well the tunnel corner including the vanes. In addition, the influence of the vanes number and their shape on the ventilator power needed and the flow velocity uniformity as well, have been subjects of the investigation. Also the ventilator type (rotational segment) impact on the flow pattern within the operational area has been scrutinized.

scholarly journals Turning Analysis during Standardized Test Using On-Shoe Wearable Sensors in Parkinson’s Disease

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3103 ◽  
Author(s):  
Nooshin Haji Ghassemi ◽  
Julius Hannink ◽  
Nils Roth ◽  
Heiko Gaßner ◽  
Franz Marxreiter ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Standardized Test ◽  
Wearable Sensors ◽  
Motor Impairment ◽  
Parameters Analysis ◽  
Pathological Gait ◽  
Spatio Temporal ◽  
Disease Stages ◽  
Insight Into

Mobile gait analysis systems using wearable sensors have the potential to analyze and monitor pathological gait in a finer scale than ever before. A closer look at gait in Parkinson’s disease (PD) reveals that turning has its own characteristics and requires its own analysis. The goal of this paper is to present a system with on-shoe wearable sensors in order to analyze the abnormalities of turning in a standardized gait test for PD. We investigated turning abnormalities in a large cohort of 108 PD patients and 42 age-matched controls. We quantified turning through several spatio-temporal parameters. Analysis of turn-derived parameters revealed differences of turn-related gait impairment in relation to different disease stages and motor impairment. Our findings confirm and extend the results from previous studies and show the applicability of our system in turning analysis. Our system can provide insight into the turning in PD and be used as a complement for physicians’ gait assessment and to monitor patients in their daily environment.

CFD Simulation of Thermal Plume and Firebrands Scattering in Urban Fire

2004 ◽  
Vol 23 (2) ◽  
pp. 152-163 ◽  
Author(s):  
Hong Huang ◽  
Ryozo Ooka ◽  
Shinsuke Kato ◽  
Hiroshi Otake ◽  
Yoshihiko Hayashi
Keyword(s):  
Cfd Simulation ◽  
Thermal Plume ◽  
Urban Fire

CFD Performance Analysis of a Flowmaker

2006 ◽  
Author(s):  
Lasse A. Rosendahl ◽  
Xiaopeng Wang ◽  
Christian B. Jacobsen
Keyword(s):  
Cfd Simulation ◽  
Laser Doppler Anemometry ◽  
Near Field ◽  
Proximity Effects ◽  
Scale Model ◽  
Valuable Insight ◽  
Mean Flow ◽  
Multiple Frame ◽  
Wall Proximity ◽  
Insight Into

In the present work, the mean flow field in a stirred tank equipped with a scale model of a commercially available Grundfos AFG.40.230.35 flowmaker is investigated using CFD simulation and Laser Doppler Anemometry (LDA), in order to provide information on the interaction between flow, propeller and wall proximity. The propeller is placed at a specified location in the tank, and measurements are taken at various locations in the tank to provide as detailed a representation of the resulting flow as possible as well as insight into the near-field of the flowmaker. The simulation, carried out with Ansys CFX 10, used a multiple frame of reference (MFR) approach to include a full representation of the flowmaker blade and motor geometry, to fully include the effects of the blade shape and variable pitch. The reported results are based on a k-e model using a second order discretization scheme. The results show good agreement on downstream axial velocities immediately after the flowmaker, although the numerical results exhibit symmetry to a greater extent than the experimental data, which is believed to be due to a combination of wall proximity effects in the latter and the turbulence model in the latter. However, the results provide valuable insight into the performance of CFD analysis on this type of flow maker, and highlight aspects for future work.

scholarly journals Growth oscillation in larger foraminifera

Paleobiology ◽  
10.1666/13051 ◽  
2014 ◽  
Vol 40 (3) ◽  
pp. 494-509 ◽  
Author(s):  
Antonino Briguglio ◽  
Johann Hohenegger
Keyword(s):  
Cell Growth ◽  
Test Chamber ◽  
Three Dimensional ◽  
Benthic Fauna ◽  
Larger Foraminifera ◽  
Three Dimensional Model ◽  
Larger Benthic Foraminifera ◽  
Growth Oscillation ◽  
Insight Into ◽  
Gaining Insight

This work shows the potential for applying three-dimensional biometry to studying cell growth in larger benthic foraminifera. The volume of each test chamber was measured from the three-dimensional model obtained by means of computed tomography. Analyses of cell growth based on the sequence of chamber volumes revealed constant and significant oscillations for all investigated specimens, characterized by periods of approximately 15, 30, 90, and 360 days. Possible explanations for these periods are connected to tides, lunar cycles, and seasonality. The potential to record environmental oscillations or fluctuations during the lifetime of larger foraminifera is pivotal for reconstructing short-term paleoenvironmental variations or for gaining insight into the influence of tides or tidal current on the shallow-water benthic fauna in both recent and fossil environments.

Study on a Multi-Layer Analytical Model of Natural Ventilation in Large Single-Cell Buildings

Solar Energy ◽  
2005 ◽  
Author(s):  
Jun Gao ◽  
Jia-Ning Zhao ◽  
Fu-Sheng Gao ◽  
Jing Liu ◽  
Zhao-Jun Wang
Keyword(s):  
Single Cell ◽  
Analytical Model ◽  
Flow Rate ◽  
Thermal Stratification ◽  
Natural Ventilation ◽  
Cfd Simulation ◽  
Thermal Plume ◽  
Boundary Treatment ◽  
Vertical Walls ◽  
Basic Equations

In large single-cell buildings, a multi-layer analytical model of natural ventilation is presented in this paper. The fluid mechanics of a plume developing in multi-layer environment is investigated based on the plume theory. Using the basic equations for a thermal plume, a mathematical model demonstrating this mechanics is established. Multi-layer thermal stratification of air density or temperature is considered driven by heat flux along wall surfaces. Airflow along vertical walls is modeled with two separate methods, one considering separate wall plumes for each layer and another modeling continuous airflow along the whole wall surface. A multi-layer model is established through balance equations for mass flow rate and heat in each layer. Two separate multi-layer models are presented and then are used to predict the ventilation flow rate and vertical temperature profiles. CFD simulation is also carried out using the RNG κ-ε model, together with an enhanced wall boundary treatment. Results of both present models are compared with those of CFD simulation. Comparisons of the results show that one model using turbulent boundary layer to calculate continuous airflow along vertical walls gives more reasonable and reliable predictions than the other one.

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