Application of Schlieren Photography to Study Neutral Plane in a Compartment Fire With Scale Models

2013 ◽  
Author(s):  
Chung-Hwei Su ◽  
Yu-Pei Ke ◽  
W. K. Chow ◽  
Ming-Chih Hsu
Keyword(s):  
Neutral Plane ◽  
Scale Model ◽  
Compartment Fire ◽  
Hot Air ◽  
Highly Sensitive ◽  
Scale Models ◽  
Schlieren Photography ◽  
Candle Flame ◽  
Photography Method ◽  
Model Room

In this paper, the neutral plane in a compartment fire was measured by Optical Schlieren Photography. This is a highly sensitive, optical, nonintrusive and remote technique to visualize fluid flow, utilizing refraction when light passes through air of different densities. The positions and variations of hot air flowing out of an opening can be determined clearly. A 1/14 scale model room burning candles inside was used. Hot air induced by the candle flame flowing out a 15 cm opening was observed. Thermocouples were also placed at the opening to compare with the neutral plane determined by the Schlieren Photography method. Simulations with Computational Fluid Dynamics were performed to justify the observed locations of the neutral planes.

scholarly journals The Winter Habitat Selection of Red Deer (Cervus elaphus) Based on a Multi-Scale Model

Animals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2454
Author(s):  
Yue Sun ◽  
Yanze Yu ◽  
Jinhao Guo ◽  
Minghai Zhang
Keyword(s):  
Habitat Selection ◽  
Environmental Factors ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Scale Model ◽  
Winter Habitat ◽  
Multi Scale ◽  
Optimal Scale ◽  
Scale Models ◽  
Selection Of

Single-scale frameworks are often used to analyze the habitat selections of species. Research on habitat selection can be significantly improved using multi-scale models that enable greater in-depth analyses of the scale dependence between species and specific environmental factors. In this study, the winter habitat selection of red deer in the Gogostaihanwula Nature Reserve, Inner Mongolia, was studied using a multi-scale model. Each selected covariate was included in multi-scale models at their “characteristic scale”, and we used an all subsets approach and model selection framework to assess habitat selection. The results showed that: (1) Univariate logistic regression analysis showed that the response scale of red deer to environmental factors was different among different covariate. The optimal scale of the single covariate was 800–3200 m, slope (SLP), altitude (ELE), and ratio of deciduous broad-leaved forests were 800 m in large scale, except that the farmland ratio was 200 m in fine scale. The optimal scale of road density and grassland ratio is both 1600 m, and the optimal scale of net forest production capacity is 3200 m; (2) distance to forest edges, distance to cement roads, distance to villages, altitude, distance to all road, and slope of the region were the most important factors affecting winter habitat selection. The outcomes of this study indicate that future studies on the effectiveness of habitat selections will benefit from multi-scale models. In addition to increasing interpretive and predictive capabilities, multi-scale habitat selection models enhance our understanding of how species respond to their environments and contribute to the formulation of effective conservation and management strategies for ungulata.

Validating Numerical CFD Simulations With Experimental Data for Turbulence Phenomena in Axial Flow Gas Turbine Diffusers

2009 ◽  
Author(s):  
Farrokh Zarifi-Rad ◽  
Hamid Vajihollahi ◽  
James O’Brien
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Axial Flow ◽  
Experimental Results ◽  
Scale Model ◽  
Data Set ◽  
Pressure Profiles ◽  
Scale Models ◽  
Inlet Conditions

Scale models give engineers an excellent understanding of the aerodynamic behavior behind their design; nevertheless, scale models are time consuming and expensive. Therefore computer simulations such as Computational Fluid Dynamics (CFD) are an excellent alternative to scale models. One must ask the question, how close are the CFD results to the actual fluid behavior of the scale model? In order to answer this question the engineering team investigated the performance of a large industrial Gas Turbine (GT) exhaust diffuser scale model with performance predicted by commercially available CFD software. The experimental results were obtained from a 1:12 scale model of a GT exhaust diffuser with a fixed row of blades to simulate the swirl generated by the last row of turbine blades five blade configurations. This work is to validate the effect of the turbulent inlet conditions on an axial diffuser, both on the experimental front and on the numerical analysis approach. The object of this work is to bring forward a better understanding of velocity and static pressure profiles along the gas turbine diffusers and to provide an accurate experimental data set to validate the CFD prediction. For the CFD aspect, ANSYS CFX software was chosen as the solver. Two different types of mesh (hexagonal and tetrahedral) will be compared to the experimental results. It is understood that hexagonal (HEX) meshes are more time consuming and more computationally demanding, they are less prone to mesh sensitivity and have the tendancy to converge at a faster rate than the tetrahedral (TET) mesh. It was found that the HEX mesh was able to generate more consistent results and had less error than TET mesh.

scholarly journals Roughness Lengths for Momentum and Heat Derived from Outdoor Urban Scale Models

2007 ◽  
Vol 46 (7) ◽  
pp. 1067-1079 ◽  
Author(s):  
M. Kanda ◽  
M. Kanega ◽  
T. Kawai ◽  
R. Moriwaki ◽  
H. Sugawara
Keyword(s):  
Wind Direction ◽  
Roughness Length ◽  
Scale Dependence ◽  
Scale Model ◽  
Small Scale ◽  
Physical Scale ◽  
Scale Models ◽  
Roughness Lengths ◽  
Urban Sites ◽  
Obstacle Height

Abstract Urban climate experimental results from the Comprehensive Outdoor Scale Model (COSMO) were used to estimate roughness lengths for momentum and heat. Two different physical scale models were used to investigate the scale dependence of the roughness lengths; the large scale model included an aligned array of 1.5-m concrete cubes, and the small scale model had a geometrically similar array of 0.15-m concrete cubes. Only turbulent data from the unstable boundary layers were considered. The roughness length for momentum relative to the obstacle height was dependent on wind direction, but the scale dependence was not evident. Estimated values agreed well with a conventional morphometric relationship. The logarithm of the roughness length for heat relative to the obstacle height depended on the scale but was insensitive to wind direction. COSMO data were used successfully to regress a theoretical relationship between κB−1, the logarithmic ratio of roughness length for momentum to heat, and Re*, the roughness Reynolds number. Values of κB−1 associated with Re* for three different urban sites from previous field experiments were intercompared. A surprising finding was that, even though surface geometry differed from site to site, the regressed function agreed with data from the three urban sites as well as with the COSMO data. Field data showed that κB−1 values decreased as the areal fraction of vegetation increased. The observed dependency of the bulk transfer coefficient on atmospheric stability in the COSMO data could be reproduced using the regressed function of Re* and κB−1, together with a Monin–Obukhov similarity framework.

Semi-automatic calibration procedure for the vision-robot interface applied to scale model decoration

Robotica ◽  
1992 ◽  
Vol 10 (4) ◽  
pp. 303-308
Author(s):  
Luis Gonzaga Trabasso ◽  
Cezary Zielinski
Keyword(s):  
Three Dimensional ◽  
Robot Vision ◽  
Work Load ◽  
Calibration Procedure ◽  
Scale Model ◽  
Three Dimensional Objects ◽  
University Of Technology ◽  
Scale Models ◽  
Set Up ◽  
Small Work

SUMMARYA semi-automatic method for calibrating a robot-vision interface is presented. It puts a small work-load on the operator, requires a simple calibration jig and a solution of a very simple system of equations. It has been extensively used in an experimental robotic cell set up at Loughborough University of Technology, where various aspects of the manufacturing and the decoration of scale models are being investigated. As an extension of the calibration procedure, the paper also shows practical solutions for the problem of dealing with three dimensional objects using a single camera.

Lobed grilles for high mixing ventilation – An experimental analysis in a full scale model room

2011 ◽  
Vol 46 (3) ◽  
pp. 547-555 ◽  
Author(s):  
Ilinca Nastase ◽  
Amina Meslem ◽  
Iordache Vlad ◽  
Iolanda Colda
Keyword(s):  
Experimental Analysis ◽  
Full Scale ◽  
Scale Model ◽  
Model Room

scholarly journals Effect of Turf Roof Slabs on Indoor Thermal Performance in Tropical Climates: A Life Cycle Cost Approach

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
R. U. Halwatura
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Air Conditioning ◽  
Green Roof ◽  
Green Roofs ◽  
Scale Model ◽  
Small Scale ◽  
Indoor Temperature ◽  
Scale Models ◽  
Different Types

Urbanization related to population growth is one of the burning issues that the world is facing today. Parallel to this, there is visible evidence of a possible energy crisis in the near future. Thus, scientists have paid attention to sustainable development methods, and in the field of building construction also, several innovations have been proposed. For example, green roof concept is one of such which is considered a viable method mainly to reduce urban heat island effect, to regain lost land spaces in cities, and to increase aesthetics in cities. The present study was aimed at investigating the impact of green roofs on indoor temperature of buildings, the effect of different types of roofs on the air conditioning loads, and the life cycle cost of buildings with different types of roofing. The study was conducted in several phases: initial small-scale models to determine the heat flow characteristics of roof top soil layers with different thicknesses, a large-scale model applying the findings of the small-scale models to determine temperature fluctuations within a building with other common roofing systems, a computer simulation to investigate air conditioning loads in a typical building with cement fiber sheets and green roof slabs, a comparative analysis of the effect of traditional type roofs and green roofs on the air conditioning loads, and finally an analysis to predict the influence of traditional type roofs and green roofs on life cycle cost of the buildings. The main findings of the study were that green roofs are able to reduce the indoor temperature of buildings and are able to achieve better heat transfer through the roof, and, thus a lower cooling load is necessary for air conditioning and has the possibility of reducing life cycle cost of a building.

scholarly journals Prefabricated Futures: Adaptable and productive construction methods for New Zealand dwellings

2021 ◽  
Author(s):  
◽  
Mitchell Holden
Keyword(s):  
New Zealand ◽  
Scale Model ◽  
Package Design ◽  
Home Owner ◽  
Construction Methods ◽  
Physical Scale ◽  
Scale Models ◽  
Building Information ◽  
Roof Panel ◽  
Traditional Construction

<p>The traditional construction method of the New Zealand home has remained largely unchanged over the last century. These housing solutions that have supported our nation no longer suffice and the ‘young home owner’ is becoming a distant dream. New Zealand needs homes, and fast. Specialised trades create fragmentation in construction. This results in inefficient processes that divide the stages of constructing a home. What lacks in these instances is accessibility to design. Architects tend to focus on one-off, bespoke builds, whilst transportable home companies create generic, minimum spec designs. It can be argued that current prefabricated solutions are not complete, requiring sub-trades and work onsite that causes delays and construction related setbacks.  Investigation into a key historic precedent has driven this research. This demonstrates that attempts have been made to change the housing model in New Zealand with some success. The precedent aligns with past notions in considering core parts of the home as products. This can create efficiencies in construction. The current demand for housing provides the perfect opportunity to reboot the method in which we build.  This thesis questions how offsite panel assemblies can create a complete prefabricated housing product and improve construction efficiencies. This will still offer architectural choice.  BIM (Building Information Modelling) and parameter driven design are used as a vehicle to demonstrate how more efficient, more collaborative and more controlled design approaches can be developed in order to create a complete construction package.  Design-led research involving constant scale model testing and development led to my prefabricated wall panel design. Named the LapLock panel, I have developed a complete wall, floor and roof panel product system. Designed to be fully fabricated from structure to claddings and services in factory. This produces ruthless efficiencies onsite. The work utilises BIM in the form of Revit and takes advantage of parameter driven families to allow for fast manipulation and output of drawings for panels. A constant conversation between analogue and digital tools (in the form of physical scale models and Revit) strengthened the understandings of the limitations throughout the research.  This thesis offers a new way of considering how New Zealand builds homes. By introducing adaptable and efficient panels that are complete on arrival to site, the Laplock solution provides accessible architectural choice to clients. This future-proofs the construction of the New Zealand home.</p>

scholarly journals Noise characteristic analysis and sound sources identification for rod–airfoil interaction using different subgrid-scale models

2021 ◽  
Vol 233 ◽  
pp. 04036
Author(s):  
Chenghao Yang ◽  
Heying Feng ◽  
Yehui Peng
Keyword(s):  
Energy Transport ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Scale Model ◽  
Subgrid Scale ◽  
Characteristic Analysis ◽  
Sound Sources ◽  
Eddy Simulation ◽  
Scale Models ◽  
The Impact

Four subgrid-scale models based on large eddy simulation (LES), such as Smagorinsky–Lilly (SL), dynamic Smagorinsky–Lilly (DSL), wall-adapting local eddy-viscosity (WALE), and dynamic kinetic-energy transport (KET) were used and couple Ffowcs Williams–Hawkings equation to accurately analyze and identify the characteristics and position of the sound sources of rod–airfoil interaction. The results of four models were compared with experimental data. It was found that the DSL model was the optimal subgrid-scale model for the study of the interaction noise considering the calculation accuracy. Therefore, the DSL model was selected for analyzing and identifying the characteristics and location of the interaction noise source. During the calculation, solid and permeable data surfaces were used for acoustic integral surfaces. The results show that the impact of the quadrupole source is negligible at a low Mach number, and the dipole noise coming from the pressure fluctuations is dominant. Meanwhile, the dipole noise from the airfoil is louder than that from the rod; the leading edge of about 30% chord length of airfoil the is the main sound source of interference effect. Above results can provide guidance for research of blade-vortex interaction noise.

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