Computational and Experimental Study for Reducing Forebody Wake Effect by Proper Designing of a Slit cut Square Parachute used for Sonobuoy Drop

This paper discusses the design of a square parachute based on classical approach, computational analysis and experimentation. This parachute will be used to drop directional sonobuoy on the sea to locate and classify the submarines. Design improvements are brought out by providing slits into a solid square canopy of parachute to bring in more stability and minimum drift during descend. Specifically, the effect of upstream sonobuoy, RANS model, suspension line length, canopy size and slit size in flow structure were considered. The predicted drag coefficients obtained from CFD for square canopy with slit-cuts compared with the results of wind tunnel experiment and found that the increase in the suspension-line length and/or of the surface area of the parachute canopy helps in better stability and results in the minimum drag loss.

Download Full-text

Experimental Study on the Effect of Reynolds Number Variation on Drag Force for Various Cut Angle on D-Type Cylinders

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.493.140 ◽

2014 ◽

Vol 493 ◽

pp. 140-144

Author(s):

Astu Pudjanarsa ◽

Ardian Ardawalika

Keyword(s):

Experimental Study ◽

Reynolds Number ◽

Drag Force ◽

Free Stream ◽

Force Balance ◽

Stream Velocity ◽

Turning Angle ◽

Subsonic Wind Tunnel ◽

Minimum Drag ◽

Number Variation

Experimental study on the effect of Reynolds number variation on drag force for various cut angles on D-type cylinders was performed. Five different cut angles on different cylinders were applied including: 35o, 45o, 53o, 60o, and 65o. The free stream velocity was varied so the Reynolds number also varied.The experiment was carried out at a subsonic wind tunnel. Drag force for a cut D-type cylinder (for example 35o) was measured using a force balance and wind speed was varied so that corresponding Reynolds number of 2.4×104÷5.3×104 were achieved. Wind turning angle was kept at 0o (without turning angle). This experiment repeated for other D-type cylinders.Experiment results show that, for all D-type cylinders, drag force decreased as the Reynolds number increased, then it was increased after attain minimum drag force. For all D-type cylinders and all variations of Reynolds number the drag minimum is attained at cut angle of 53o. This value is appropriate with previous experiment results.

Download Full-text

Numerical Computation of Phase Separation in Two Fluid Flow

Journal of Fluids Engineering ◽

10.1115/1.3243091 ◽

1984 ◽

Vol 106 (2) ◽

pp. 147-153 ◽

Cited By ~ 44

Author(s):

M. B. Carver

Keyword(s):

Experimental Study ◽

Fluid Flow ◽

Phase Separation ◽

Numerical Computation ◽

Computational Analysis ◽

Fluid Flows ◽

Iterative Approach ◽

Two Fluid

A new iterative approach is outlined for multidimensional computational analysis of two fluid flow. Parametric surveys are described to illustrate that the method rationally predicts separation of two fluid flows under gravitational and centrifugal influences. A comparison is made between behavior computed by the method, and results reported in an experimental study of air and water flowing in elbows and pipes.

Download Full-text

Experimental study of unsteady wake effect on a film-cooled pitchwise-curved surface

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2014.11.042 ◽

2015 ◽

Vol 83 ◽

pp. 118-135 ◽

Cited By ~ 1

Author(s):

Srikrishna Mahadevan ◽

Barkin F. Kutlu ◽

Matthew J. Golsen ◽

Shashi B. Verma ◽

Jayanta S. Kapat

Keyword(s):

Experimental Study ◽

Curved Surface ◽

Wake Effect ◽

Unsteady Wake

Download Full-text

Transient Effects in the Lubrication of Hertzian Contacts

Journal of Mechanical Engineering Science ◽

10.1243/jmes_jour_1971_013_030_02 ◽

1971 ◽

Vol 13 (3) ◽

pp. 173-189 ◽

Cited By ~ 50

Author(s):

J. P. Vichard

Keyword(s):

Experimental Study ◽

Steady State ◽

Reynolds Equation ◽

Hydrodynamic Theory ◽

Classical Approach ◽

Transient Effects ◽

Thermal Origin ◽

Squeeze Effect ◽

Rigid Surfaces ◽

Theoretical Results

Analysis of the lubrication of mechanisms such as gears, roller bearings and cams shows that their contacts involve a squeeze effect when they operate. The classical approach, however, is to limit investigations to steady state conditions. The aim of our work is to estimate the validity of this hypothesis. First, we shall examine the behaviour of contacts with rigid surfaces and we shall compare the results with the Martin theory. The straightforwardness of the derivation of the Reynolds equation allows us to study the effect thoroughly. The squeeze effect contributes to damp down the variations of the external parameters, such as load or speed. Secondly, this result is confirmed in elasto-hydrodynamic theory. In this case the exact calculation is too complicated and we have used the Grubin's approximation. Finally, an experimental study will confirm the theoretical results and will show a phenomenon which has a thermal origin.

Download Full-text

High-Temperature Pyrolysis of Liquified Petroleum Gases in the Fast-Mixing Reactor

International Journal of Chemical Reactor Engineering ◽

10.1515/1542-6580.2565 ◽

2011 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Marat Ktalkherman ◽

Igor Namyatov ◽

Vladimir Emel'kin

Keyword(s):

Experimental Study ◽

Heat Carrier ◽

Mass Fraction ◽

Computational Analysis ◽

Small Scale ◽

Pyrolysis Products ◽

Temperature Growth ◽

Reactor Inlet ◽

High Enthalpy ◽

Steam Cracking

Experimental study and computational analysis of a pyrolysis of liquefied petroleum gases (LPG) in a high-enthalpy heat carrier flow are presented. The experiments on a small-scale device were carried out within the temperature range at the reactor inlet of 1,350-1,500 K, which is essentially higher than the typical values in the conventional method of steam cracking. Increased initial temperatures required to realize in the experiments the ultra-fast mixing of the feedstock with heat carrier (~0.05 ms). The rate of feedstock temperature growth in the mixer was about 107 K/s. The ethylene mass fraction in pyrolysis products in our experiments reached 47%.

Download Full-text

Experimental study on the minimum drag coefficient of supercritical pressure water in horizontal tubes

Nuclear Engineering and Design ◽

10.1016/j.nucengdes.2016.02.039 ◽

2016 ◽

Vol 301 ◽

pp. 164-174 ◽

Cited By ~ 3

Author(s):

Xianliang Lei ◽

Huixiong Li ◽

YuMeng Guo ◽

Qing Zhang ◽

Weiqiang Zhang ◽

...

Keyword(s):

Experimental Study ◽

Drag Coefficient ◽

Supercritical Pressure ◽

Horizontal Tubes ◽

Minimum Drag ◽

Pressure Water ◽

Supercritical Pressure Water

Download Full-text

Experimental study and computational analysis on pedestrians behaviour walking through angled-corridor

10.1063/1.5066888 ◽

2018 ◽

Author(s):

N. A. Rahman ◽

S. H. M. Adenan ◽

N. A. Alias ◽

N. H. Kasehyani ◽

N. S. A. Sukor ◽

...

Keyword(s):

Experimental Study ◽

Computational Analysis

Download Full-text

A New Mechanism Explaining High Frequency Chatter Vibration Involving Tool Tip X-Y Looping in Fine Boring

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.1387017 ◽

2000 ◽

Vol 123 (3) ◽

pp. 370-376 ◽

Cited By ~ 3

Author(s):

Evita Edhi ◽

Tetsutaro Hoshi

Keyword(s):

Experimental Study ◽

Tool Life ◽

Structural Dynamics ◽

High Frequency ◽

Computational Analysis ◽

Chatter Vibration ◽

Penetration Effect ◽

Regenerative Effect ◽

Boring Tool ◽

Fine Boring

Chatter occurring at more than 10,000 Hz frequency was found in fine boring operation, and causing reduced tool life. To identify the mechanism for the onset of high frequency chatter, cutting tests and structural dynamics examination of the boring tool have been performed. Experimental study has revealed that the regenerative effect, the penetration effect, and the X-Y looping of the tool tip are three relevant characteristics in the onset of the chatter. Those findings are included in a new chatter model of which validity is evaluated by computational analysis of energy supplied and dissipated in the vibrating system.

Download Full-text

An Experimental Study on Heat Transfer Around Two Side-by-Side Closely Arranged Circular Cylinders

Journal of Heat Transfer ◽

10.1115/1.4002147 ◽

2010 ◽

Vol 132 (11) ◽

Cited By ~ 4

Author(s):

Takayuki Tsutsui

Keyword(s):

Heat Transfer ◽

Experimental Study ◽

Free Stream ◽

Local Heat Transfer ◽

Local Heat ◽

Circular Cylinders ◽

Stream Velocity ◽

Heat Transfer Characteristics ◽

Minimum Drag ◽

Coefficient Condition

The present paper describes heat transfer around two side-by-side closely arranged circular cylinders. The flows around two circular cylinders in a side-by-side arrangement can be classified into three flow patterns according to the gap between the two cylinders. The heat transfer characteristics of the cylinders in each flow regime were experimentally investigated. The diameter of the circular cylinders was 40 mm and the gap between the two cylinders varied from 4 mm to 40 mm. The free stream velocity ranged from 4 m/s to 24 m/s, resulting in Reynolds nos. ranging from 1.1×104 to 6.2×104. The local heat transfer coefficient of both cylinders was measured. The overall Nusselt no. of the two cylinders was found to be minimum at G/D(=gap/diameter)=0.4, which is the minimum drag coefficient condition of the two cylinders, too.

Download Full-text

Development of an Experimental Setup for Double Rotor HAWT Investigation

Volume 6: Oil and Gas Applications; Concentrating Solar Power Plants; Steam Turbines; Wind Energy ◽

10.1115/gt2012-70032 ◽

2012 ◽

Cited By ~ 4

Author(s):

Ali Al-Abadi ◽

Özgür Ertunç ◽

Philipp Epple ◽

Wolfram Koerbel ◽

Antonio Delgado

Keyword(s):

Experimental Study ◽

Kinetic Energy ◽

Theoretical Analysis ◽

Power Coefficient ◽

Total Power ◽

Experimental Setup ◽

Wake Effect ◽

Horizontal Axis Wind Turbines ◽

Set Up ◽

Speed Characteristic

An experimental set-up was designed and constructed to study the performance of single and double rotor Horizontal Axis Wind Turbines (HAWT) configurations. Different tip speed ratios (TSR) were tested under varying wind loadings. The experimental study was carried out in order to investigate the HAWT performance and thereby increase its aerodynamics efficiency. Another setup was built to measure the torque rotational speed characteristic of the generator. The double rotor configuration was chosen intentionally to study the efficiency improvements when the second downstream rotor extracts the kinetic energy dismissed by the upstream rotor. The study showed that the power coefficient can be indeed increased about 50% with a double rotor HAWT configuration, and the power gained from a counter rotating rotor is higher than that of a co-rotating rotor owing to the effect of the wake of the upstream rotor. In addition, a theoretical analysis of wake effect of the upstream rotor on the downstream rotor including the effect of the distance between the two rotors on the total power coefficient was made and investigated experimentally in order to estimate the optimum distance between the two rotors.

Download Full-text