Assessment on Thermal Sensitivity of Fusable Links With a Wind Tunnel

2007 ◽  
Author(s):  
W. K. Chow ◽  
Angus C. K. Cheng
Keyword(s):  
Wind Tunnel ◽  
Air Temperature ◽  
Thermal Sensitivity ◽  
Thermal Response ◽  
Air Speed ◽  
International Testing ◽  
Testing Standards ◽  
Working Section

This is a paper on exploring how codes on assessing thermal sensitivity of fusable links for controlling fire shutters can be established. Typical samples of fusable links were tested in a wind tunnel for studying the thermal response of sprinkler heads. In the test, the fusable link samples were loaded under 0.4 kgf. The working section of the tunnel was set at air temperature of 135°C and air speed of 2.54 ms−1. Results suggested that it is feasible to assess the thermal sensitivity of fusable links by following international testing standards.

Independence of brain and body temperatures in flying American kestrels, Falco sparverius

1979 ◽  
Vol 237 (1) ◽  
pp. R58-R62
Author(s):  
M. H. Bernstein ◽  
M. B. Curtis ◽  
D. M. Hudson
Keyword(s):  
Steady State ◽  
Wind Tunnel ◽  
Air Temperature ◽  
Body Temperatures ◽  
Air Temperatures ◽  
American Kestrels ◽  
Steady State Levels ◽  
Air Speed ◽  
State Difference ◽  
Body Heat

Brain and body temperatures were measured via small thermocouples implanted in the anterior hypothalami and colons, respectively, of five adult American kestrels (F. sparverius, mean mass 119 g) during descending flights in a wind tunnel at angles of 4 and 6 degrees below horizontal, at 10 m.s-1 air speed, and at 23 degrees C air temperature. For comparison, temperatures were recorded from resting birds at 22.5-36.1 degrees C air temperatures. Colonic (Tc) and hypothalamic (Th) temperatures both increased after the onset of flight; steady-state levels were attained after 1 min in the hypothalamus and after 5 or more min in the colon. The steady-state difference (delta T = Tc - Th) averaged 1.2 degrees C, higher by 0.5 degrees C than delta T in resting kestrels. The establishment of delta T during flight may be correlated with increased respiratory and corneal evaporation. The response apparently confines most stored body heat to noncranial regions, thus protecting brain tissue from thermal extremes.

Influence of the Side Walls on the Turbulent Center-Plane Boundary-Layer in a Square Duct

1978 ◽  
Vol 100 (1) ◽  
pp. 91-96 ◽  
Author(s):  
V. de Brederode ◽  
P. Bradshaw
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Flat Plate ◽  
Cross Section ◽  
Secondary Flows ◽  
Plane Boundary ◽  
Square Duct ◽  
Streamwise Pressure Gradient ◽  
Side Walls ◽  
Working Section

Measurements in the entry region of a square duct (specifically, a wind-tunnel working section) show that the direct effect of stress-induced secondary flows in the corners on the center-plane boundary layer is negligible for boundary layers thinner than about one-fourth of the duct width. Further, the effects of streamwise pressure gradient and of quasi-collinear lateral convergence tend to cancel so that the velocity profiles and skin friction are quite close to those on a flat plate. This shows that the boundary layer on the floor of a wind tunnel of constant, square cross section can be used to simulate a flat-plate flow even when the boundary layer thickness is as large as one-fourth of the tunnel height.

Instability in slotted wall tunnels

1958 ◽  
Vol 4 (3) ◽  
pp. 283-305 ◽  
Author(s):  
J. L. King ◽  
P. Boyle ◽  
J. B. Ogle
Keyword(s):  
Wind Tunnel ◽  
Experimental Evidence ◽  
Theoretical Explanation ◽  
Water Tunnel ◽  
Design Consideration ◽  
Working Section

A new water tunnel, incorporating a slotted wall working section, was found to suffer from severe vibration. A theoretical explanation is given for this, together with experimental evidence gleaned from this water tunnel and a small wind tunnel. It is shown that the oscillations are hydrodynamic in origin and are associated with the slotted wall design. Consideration is given to methods of elimination or reduction of the oscillations.

Wingbeat frequency of barn swallows and house martins: a comparison between free flight and wind tunnel experiments

2002 ◽  
Vol 205 (16) ◽  
pp. 2461-2467 ◽  
Author(s):  
Felix Liechti ◽  
Lukas Bruderer
Keyword(s):  
Wind Tunnel ◽  
Single Pulse ◽  
Free Flight ◽  
Wind Tunnel Experiments ◽  
Wingbeat Frequency ◽  
Flight Costs ◽  
Radar Echo ◽  
The Mean ◽  
Barn Swallows ◽  
Air Speed

SUMMARYThe flight paths and wingbeat patterns of 39 barn swallows (Hirundo rustica) and 26 house martins (Delichon urbica) were recorded by tracking radar during the spring migration. Depending mostly on flight angle,hirundines performed anything from continuous flapping flight during climbing to single pulse-like wing beats during descent. Unlike most other passerines,hirundines rarely showed regular flapping and rest phases, allowing them to be distinguished from other bird migrants by radar echo signatures. Effective wingbeat frequency (Feff) was calculated as the mean number of wing beats per second, including non-flapping phases. Under comparable flight conditions, Feff was higher in house martins than in barn swallows. Within species, Feff values were higher during climbing and slow flying than during descent. Of the variance in Feff, 71 % could be explained by climb rate,air speed and species; similar results were obtained in the wind tunnel. Under comparable flight conditions, barn swallows and house martins in free flight had significantly lower values of Feff than individuals in wind tunnel experiments (by 40 % and 32 %, respectively). This difference may at least partly be due to the shorter wings of the juveniles tested in the wind tunnel during autumn. However, it seems unlikely that this can account for all of the large difference. It is suggested that wind tunnel experiments might overestimate birds' flight costs compared with free flight.

Aerodynamics of Gliding Flight of a Black Vulture Coragyps Atratus

1970 ◽  
Vol 53 (2) ◽  
pp. 363-374 ◽  
Author(s):  
G. CHRISTIAN PARROTT
Keyword(s):  
Wind Tunnel ◽  
Wing Area ◽  
Drag Coefficients ◽  
Wing Span ◽  
Drag Forces ◽  
Gliding Flight ◽  
Black Vulture ◽  
Air Speed

1. A black vulture (mass = 1.79 kg) gliding freely in a wind tunnel adjusted its wing span and wing area as its air speed and glide angle changed from 9.9 to 16.8 m/s and from 4.8° to 7.9°, respectively. 2. The minimum sinking speed was 1.09 m/s at an air speed of 11.3 m/s. 3. The maximum ratio of lift to drag forces was 11.6 at an air speed of 13.9 m/s. 4. Parasite drag coefficients for the vulture are similar to those for conventional airfoils and do not support the contention that black vultures have unusually low values of parasite drag.

Uncertainty Quantification of Thermocouple Air Temperature Measurement in Highly Radiative Environment: Application to Turbofan Engine Compartment

2016 ◽  
Author(s):  
Y. Sommerer ◽  
V. Drouin ◽  
X. Nicolas ◽  
B. Trouette
Keyword(s):  
Heat Flux ◽  
Temperature Measurement ◽  
Air Temperature ◽  
Data Bank ◽  
Heat Shield ◽  
Engine Compartment ◽  
Heat Shields ◽  
Air Speed ◽  
Thermocouple Temperature ◽  
The Impact

This paper focuses on thermocouple air temperature measurement uncertainty due to the radiative fluxes present in the engine compartment where engine case skin temperature can exceed 900 K. To really measure air temperature, the convective heat flux in the thermocouple bead must be predominant. This is why heat shields are used in order to reduce the radiative heat flux on the bead. However, in engine compartment, the heat shield orientation must be optimized since numerous hot walls surround the thermocouple. In order to evaluate the impact of badly oriented heat shields and to provide a data bank for numerical simulation validations, a heated wind tunnel has been used. It has been shown that the uncertainty on the thermocouple temperature can reach dozens of degrees depending on the air speed and the heat shield orientation. Furthermore a specific 3D thermocouple model has been build and validated by comparison with the lab measurements. Then this thermocouple 3D model has been integrated in the whole engine compartment aero-thermal model in order to quantify the uncertainty of the thermocouple air temperature measurement in the real engine environment.

FEM-BEM Modeling and Experimental Verification of the Vibro-Acoustic Behaviour of a Section of Aircraft Fuselage

2016 ◽  
Author(s):  
Viken N. Koukounian ◽  
Chris K. Mechefske
Keyword(s):  
Transmission Loss ◽  
Pressure Fluctuations ◽  
Experimental Methodology ◽  
Reverberation Chamber ◽  
Aircraft Fuselage ◽  
Ongoing Work ◽  
Damping Materials ◽  
Fuselage Skin ◽  
International Testing ◽  
Testing Standards

The aerodynamics of an aircraft in flight impose significant stresses upon the structure. Specifically, the mechanics of fluid flow are highly turbulent and, the layer around the aircraft, is referred to the turbulent boundary layer (TBL). The TBL incites a gradient of pressure fluctuations across the fuselage skin resulting in its vibration, and in turn, the generation of noise inside the passenger cabin. The investigation herein proposes a hybrid FEM-BEM modeling technique to predict the aforementioned vibro-acoustic response and an experimental methodology to verify the results (following ASTM and ANSI international testing standards). The described expectations required construction of an acoustic facility consisting of a reverberation chamber and a semi-anechoic room, the development of DAQ software using LabVIEW, an assembly of DAQ hardware using National Instruments products, and the post-processing of test data using Microsoft Excel. The principal quantity of interest is transmission loss (though insertion loss, absorption and other metrics are also calculated). Two panels (0.04in (40thou) and 0.09in (90thou) in thickness) were simulated and tested (0.01in = 1thou). The calculated error of the proposed methodology is within a maximum of 5dB, with an average of 1dB. Ongoing work is investigating complex constructions and the use of damping materials.

Design and Operational Problems of the Transonic Jet–Driven Wind Tunnel

1958 ◽  
Vol 62 (565) ◽  
pp. 6-11
Author(s):  
J. A. Kirk
Keyword(s):  
Wind Tunnel ◽  
Short Paper ◽  
Working Section

In this short paper on the transonic jet-driven tunnel, I will place the emphasis on the word transonic and deal only with the jet drive as it affects the design or operation of the transonic working section. I also would like to say that, although a fair amount of the information discussed afterwards will refer to the D.H. transonic tunnel, the problems are more or less general to the jet–driven tunnel and some will even be applicable to electrically–driven transonic tunnels using diffuser suction.

scholarly journals Thermal history and comfort in a Brazilian subtropical climate: a 'cool' addiction hypothesis

2016 ◽  
Vol 16 (1) ◽  
pp. 7-20 ◽  
Author(s):  
Renata De Vecchi ◽  
Christhina Maria Cândido ◽  
Roberto Lamberts
Keyword(s):  
Air Temperature ◽  
Indoor Air ◽  
Thermal History ◽  
Air Conditioning ◽  
Prolonged Exposure ◽  
Temperature Fluctuations ◽  
Subtropical Climate ◽  
Indoor Thermal Comfort ◽  
Air Speed ◽  
The Impact

Abstract Currently, there is a rising trend for commercial buildings to use air conditioning to provide indoor thermal comfort. This paper focuses on the impact of prolonged exposure to indoor air-conditioned environments on occupants' thermal acceptability and preferences in a mixed-mode building in Brazil. Questionnaires were administered while indoor microclimatic measurements were carried out (i.e., air temperature, radiant air temperature, air speed and humidity). Results suggest significant differences in occupants' thermal acceptability and cooling preferences based on thermal history; differences were found between groups based on different physical characteristics (i.e., different gender and body condition). The findings also indicated a significant potential to implement temperature fluctuations indoors when occupants are exposed to air conditioning environments in warm and humid climates.

scholarly journals 2D Numerical Simulation Study of Airfoil Performance

2021 ◽  
Author(s):  
Nasser Shelil
Keyword(s):  
Experimental Data ◽  
Wind Tunnel ◽  
Air Temperature ◽  
Wind Turbines ◽  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
Operating Conditions ◽  
Ansys Fluent

Abstract. The aerodynamic characteristics of DTU-LN221 airfoil is studied. ANSYS Fluent is used to simulate the airfoil performance with seven different turbulence models. The simulation results for the airfoil with different turbulence models are compared with the wind tunnel experimental data performed under the same operating conditions. It is found that there is a good agreement between the computational fluid dynamics (CFD) predicted aerodynamic force coefficients with wind tunnel experimental data especially with angle of attack between −5° to 10°. RSM is chosen to investigate the flow field structure and the surface pressure coefficients under different angle of attack between −5° to 10°. Also the effect of changing air temperature, velocity and turbulence intensity on lift and drag coefficients/forces are examined. The results show that it is recommended to operate the wind turbines airfoil at low air temperature and high velocity to enhance the performance of the wind turbines.

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