Abstract: The paper presents the results of simple measurements
conducted on a model of a wind-driven venturi-type room ventilator.
The ventilator design is new and was developed employing
mathematical modeling. However, the computational model was not
validated experimentally for the particular application considered.
The paper presents the performance of the ventilator model under
laboratory conditions, for five different wind tunnel speeds. The
results are used to both demonstrate the effectiveness of the new
design and to validate the computational model employed to develop
it.
Abstract: The unsteady wake of an EPPLER 361 airfoil in
pitching motion has been investigated in a subsonic wind tunnel by
hot-wire anemometry. The airfoil was given the pitching motion
about the one-quarter chord axis at reduced frequency of 0182.
Streamwise mean velocity profiles (wake profiles) were investigated
at several vertically aligned points behind the airfoil at one-quarter
chord downstream distance from trailing edge. Oscillation amplitude
and mean angle of attack were varied to determine the effects on
wake profiles. When the maximum dynamic angle of attack was
below the static stall angle of attack, weak effects on wake were
found by increasing oscillation amplitude and mean angle of attack.
But, for higher angles of attack strong unsteady effects were
appeared on the wake.
Abstract: The measurement of aerodynamic forces and moments
acting on an aircraft model is important for the development of wind
tunnel measurement technology to predict the performance of the full
scale vehicle. The potentials of an aircraft model with and without
winglet and aerodynamic characteristics with NACA wing No. 65-3-
218 have been studied using subsonic wind tunnel of 1 m × 1 m
rectangular test section and 2.5 m long of Aerodynamics Laboratory
Faculty of Engineering (University Putra Malaysia). Focusing on
analyzing the aerodynamic characteristics of the aircraft model, two
main issues are studied in this paper. First, a six component wind
tunnel external balance is used for measuring lift, drag and pitching
moment. Secondly, Tests are conducted on the aircraft model with
and without winglet of two configurations at Reynolds numbers
1.7×105, 2.1×105, and 2.5×105 for different angle of attacks. Fuzzy
logic approach is found as efficient for the representation,
manipulation and utilization of aerodynamic characteristics.
Therefore, the primary purpose of this work was to investigate the
relationship between lift and drag coefficients, with free-stream
velocities and angle of attacks, and to illustrate how fuzzy logic
might play an important role in study of lift aerodynamic
characteristics of an aircraft model with the addition of certain
winglet configurations. Results of the developed fuzzy logic were
compared with the experimental results. For lift coefficient analysis,
the mean of actual and predicted values were 0.62 and 0.60
respectively. The coreelation between actual and predicted values
(from FLS model) of lift coefficient in different angle of attack was
found as 0.99. The mean relative error of actual and predicted valus
was found as 5.18% for the velocity of 26.36 m/s which was found to
be less than the acceptable limits (10%). The goodness of fit of
prediction value was 0.95 which was close to 1.0.
Abstract: In the present paper; an experimental and numerical
investigations of drag reduction on a grooved circular cylinder have
been performed. The experiments were carried out in closed circuit
subsonic wind tunnel (TE44); the pressure distribution on the
cylinder was conducted using a TE44DPS differential pressure
scanner and the drag forces were measured using the TE81 balance.
The display unit is linked to a computer, loaded with DATASLIM
software for data analysis and logging of result. The numerical study
was performed using the code ANSYS FLUENT solving the
Reynolds Averaged Navier-Stokes (RANS) equations. The k-ε and k-
ω SST models were tested. The results obtained from the
experimental and numerical investigations have showed a reduction
in the drag when using longitudinal grooves namely 2 and 6 on the
cylinder.
Abstract: This work describes the aerodynamic characteristic for
aircraft wing model with and without bird feather like winglet. The
aerofoil used to construct the whole structure is NACA 653-218
Rectangular wing and this aerofoil has been used to compare the
result with previous research using winglet. The model of the
rectangular wing with bird feather like winglet has been fabricated
using polystyrene before design using CATIA P3 V5R13 software
and finally fabricated in wood. The experimental analysis for the
aerodynamic characteristic for rectangular wing without winglet,
wing with horizontal winglet and wing with 60 degree inclination
winglet for Reynolds number 1.66×105, 2.08×105 and 2.50×105 have
been carried out in open loop low speed wind tunnel at the
Aerodynamics laboratory in Universiti Putra Malaysia. The
experimental result shows 25-30 % reduction in drag coefficient and
10-20 % increase in lift coefficient by using bird feather like winglet
for angle of attack of 8 degree.
Abstract: The aerodynamics characteristics of a blended-wing body (BWB) aircraft were obtained in Universiti Teknologi MARA low speed wind tunnel. The scaled-down of BWB model consisted of a canard as its horizontal stabilizer. There were four canards with different aspect ratio used in the experiments. Canard setting angles were varied from -20q to 20q. All tests were conducted at velocity of 35 m/s, with Mach number 0.1. At low angles of attacks, the increment of lift slope for various canards aspect ratio is small and almost constant. Higher canard aspect ratio will cause higher drag. However, canard has a high effect to the moment at zero lift, CM,0.The visualization using mini tuff was performed to observe the airflow at the upper surface of canard. KeywordsAerodynamics,blended-wing body, canard, wind tunnel.
Abstract: A series of experiments were carried out to study
unsteady behavior of the flow field as well as the boundary layer of
an airfoil oscillating in plunging motion in a subsonic wind tunnel.
The measurements involved surface pressure distribution
complimented with surface-mounted hot-films. The effect of leadingedge
roughness that simulates surface irregularities on the wind
turbine blades was also studied on variations of aerodynamic loads
and boundary layer behavior.
Abstract: Plasma Wind Tunnels (PWT) are extensively used for screening and qualification of re-entry Thermel Protection System (TPS) materials. Proper design of a supersonic diffuser for plasma wind tunnel is of importance for achieving good pressurerecovery (thereby reducing vacuum pumping requirement & run time costs) and isolating downstream stream fluctuations from propagating costs) and isolating downstream stream fluctuationnts the details of a rapid design methodology successfully employed for designing supersonic diffuser for high power (several megawatts)plasma wind tunnels and numerical performance analysis of a diffuser configuration designed for one megawatt power rated plasma wind tunnel(enthalpy ~ 30 MJ/kg) using FLUENT 6.3® solver for different diffuser operating sub-atmospheric back-pressures.
Abstract: Shear-layer instabilities of a pulsed stack-issued
transverse jet were studied experimentally in a wind tunnel. Jet
pulsations were induced by means of acoustic excitation. Streak
pictures of the smoke-flow patterns illuminated by the laser-light sheet
in the median plane were recorded with a high-speed digital camera.
Instantaneous velocities of the shear-layer instabilities in the flow were
digitized by a hot-wire anemometer. By analyzing the streak pictures
of the smoke-flow visualization, three characteristic flow modes,
synchronized flapping jet, transition, and synchronized shear-layer
vortices, are identified in the shear layer of the pulsed stack-issued
transverse jet at various excitation Strouhal numbers. The shear-layer
instabilities of the pulsed stack-issued transverse jet are synchronized
by acoustic excitation except for transition mode. In transition flow
mode, the shear-layer vortices would exhibit a frequency that would be
twice as great as the acoustic excitation frequency.
Abstract: Feeder is one of the airships of the Multibody Advanced Airship for Transport (MAAT) system, under development within the EU FP7 project. MAAT is based on a modular concept composed of two different parts that have the possibility to join; respectively they are the so-called Cruiser and Feeder, designed on the lighter than air principle. Feeder, also named ATEN (Airship Transport Elevator Network), is the smaller one which joins the bigger one, Cruiser, also named PTAH (Photovoltaic modular Transport Airship for High altitude),envisaged to happen at 15km altitude. During the MAAT design phase, the aerodynamic studies of the both airships and their interactions are analyzed. The objective of these studies is to understand the aerodynamic behavior of all the preselected configurations, as an important element in the overall MAAT system design. The most of these configurations are only simulated by CFD, while the most feasible one is experimentally analyzed in order to validate and thrust the CFD predictions. This paper presents the numerical and experimental investigation of the Feeder “conical like" shape configuration. The experiments are focused on the aerodynamic force coefficients and the pressure distribution over the Feeder outer surface, while the numerical simulation cover also the analysis of the velocity and pressure distribution. Finally, the wind tunnel experiment is compared with its CFD model in order to validate such specific simulations with respective experiments and to better understand the difference between the wind tunnel and in-flight circumstances.
Abstract: In this study, in order to clarify wind-induced
phenomena, especially vertical mixing of density stratification in a
closed water area with floating-leaved plants, we conducted hydraulic
experiments on wind flow characteristics, wind wave characteristics,
entrainment phenomena and turbulent structure by using a wind tunnel
test tank and simulated floating-leaved plants. From the experimental
results of wind flow and wind wave characteristics, we quantified the
impact of the occupancy rate of the plants on their resistance
characteristics. From the experimental results of entrainment
phenomena, we defined the parameter that could explain the
magnitude of mixing between the density stratifications, and
quantified the impact of the occupancy rate on vertical mixing
between stratifications. From the experimental results of the turbulent
structure of the upper layer, we clarified the differences in small-scale
turbulence components at each occupancy rate and quantified the
impact of the occupancy rate on the turbulence characteristics. For a
summary of this study, we theoretically quantified wind-induced
entrainment phenomena in a closed water area with luxuriant growth
of floating-leaved plants. The results indicated that the impact of
luxuriant growth of floating-leaved plants in a closed water body
could be seen in the difference in small-scale fluid characteristics, and
these characteristics could be expressed using the small-scale
turbulent components.
Abstract: The methodology of numerical simulation and calculation of aerodynamic characteristics of aircraft taking into account impact of wake on it has been developed. The results of numerical experiment in comparison with the data obtained in the wind tunnel are presented. Efficiency of methodology of calculation and the reliability of the results is shown.
Abstract: A specially designed flat plate was mounted vertically
over the axial line in the wind tunnel of the Aerospace Department of
the Pusan National University. The plate is 2 m long, 0.8 m high and 8
cm thick. The measurements were performed in velocity range from
15 to 60 m/s. A sand paper turbulizer was placed close to the plate nose
to provide fully developed turbulent boundary layer over the most part
of the plate. Strain balances were mounted in the trailing part of the
plate to measure the skin friction drag over removable insertions of
0.55×0.25m2 size. A set of the insertions was designed and
manufactured: 3mm thick polished metal surface and three compliant
surfaces. The compliant surfaces were manufactured of a silicone
rubber Silastic® S2 (Dow Corning company). To modify the
viscoelastic properties of the rubber, its composition was varied: 90%
of the rubber + 10% catalyst (standard), 92.5% + 7.5% (weak), 85% +
15% (strong). Modulus of elasticity and the loss tangent were
measured accurately for these materials in the frequency range from
40 Hz to 3 KHz using the unique proposed technique.
Abstract: This paper deals with the conceptual design of the
new aeroelastic demonstrator for the whirl flutter simulation. The
paper gives a theoretical background of the whirl flutter phenomenon
and describes the events of the whirl flutter occurrence in the
aerospace practice. The second part is focused on the experimental
research of the whirl flutter on aeroelastic similar models. Finally the
concept of the new aeroelastic demonstrator is described. The
demonstrator represents the wing and engine of the twin turboprop
commuter aircraft including a driven propeller. It allows the changes
of the main structural parameters influencing the whirl flutter
stability characteristics. It is intended for the experimental
investigation of the whirl flutter in the wind tunnel. The results will
be utilized for validation of analytical methods and software tools.
Abstract: Over 90% of the world trade is carried by the
international shipping industry. As most of the countries are
developing, seaborne trade continues to expand to bring benefits for
consumers across the world. Studies show that world trade will
increase 70-80% through shipping in the next 15-20 years. Present
global fleet of 70000 commercial ships consumes approximately 200
million tonnes of diesel fuel a year and it is expected that it will be
around 350 million tonnes a year by 2020. It will increase the
demand for fuel and also increase the concentration of CO2 in the
atmosphere. So, it-s essential to control this massive fuel
consumption and CO2 emission. The idea is to utilize a diesel-wind
hybrid system for ship propulsion. Use of wind energy by installing
modern wing-sails in ships can drastically reduce the consumption of
diesel fuel. A huge amount of wind energy is available in oceans.
Whenever wind is available the wing-sails would be deployed and
the diesel engine would be throttled down and still the same forward
speed would be maintained. Wind direction in a particular shipping
route is not same throughout; it changes depending upon the global
wind pattern which depends on the latitude. So, the wing-sail
orientation should be such that it optimizes the use of wind energy.
We have made a computer programme in which by feeding the data
regarding wind velocity, wind direction, ship-motion direction; we
can find out the best wing-sail position and fuel saving for
commercial ships. We have calculated net fuel saving in certain
international shipping routes, for instance, from Mumbai in India to
Durban in South Africa. Our estimates show that about 8.3% diesel
fuel can be saved by utilizing the wind. We are also developing an
experimental model of the ship employing airfoils (small scale wingsail)
and going to test it in National Wind Tunnel Facility in IIT
Kanpur in order to develop a control mechanism for a system of
airfoils.