Experimental Study of the Vertical Hydraulic Drag Force on Regular Tetrahedron

2013 ◽  
Vol 860-863 ◽  
pp. 1547-1550
Author(s):  
Rui Le ◽  
Wei Jiang ◽  
Qi Liu ◽  
Nan Chang Sun ◽  
Bing Xu
Keyword(s):  
Experimental Study ◽  
Drag Coefficient ◽  
Drag Force ◽  
Vertical Velocity ◽  
Hydraulic Engineering ◽  
Hydraulic Drag ◽  
Regular Tetrahedron ◽  
Impact Effect ◽  
Drag Forces ◽  
The Impact

It is well known that the hydraulic drag force on objects cant be ignored in computing the movement of objects in water. And the drag forces on sphere and cuboids have long been studied. While in hydraulic engineering, objects with regular tetrahedron shape are widely used to form the foundation and temporary dam for they can interlock each other to obtain a compacted integral. In this article the vertical hydraulic drag force on regular tetrahedron is studied by indoor experiments, the relation of the vertical hydraulic drag coefficient and the vertical velocity is proposed. And the max vertical speeds of different materials are deduced. The result is helpful to compute the movement of regular tetrahedron in water and estimate the impact effect on the groundwork.

scholarly journals Preliminary study of software tracker usage to analyze inhibitory style on free fall movie events

2018 ◽  
Vol 197 ◽  
pp. 02012
Author(s):  
Seni Susanti ◽  
Ea Cahya Septia Mahen ◽  
Ade Yeti Nuryantini
Keyword(s):  
Drag Coefficient ◽  
Drag Force ◽  
Free Fall ◽  
Force Analysis ◽  
Drag Coefficients ◽  
Drag Forces ◽  
Preliminary Study ◽  
Free Falling ◽  
Good Agreement

This paper presents drag force analysis of free falling object using software tracker. We use video cupclips that have been embedded in this software. The video featured cupcakes to which hung a number of different paper clips were dropped simultaneously. We track the trajectory of free falling cupclips using the software to get the information of position, speed, and acceleration of each cupcake against time. From the data we get the value of drag forces and drag coefficients for each time. The result shows that the drag force value increased to almost constant value, otherwise the drag coefficient is reduced to almost constant values well. According to the results, the analyzed data has good agreement with the theory. Thus, software tracker can be used as media to learn drag force easily and inexpensively.

scholarly journals Experimental Characterization of Drag Coefficient of an UAV Recovery Parachute

2021 ◽  
Vol 31 (2) ◽  
pp. 67-74
Keyword(s):  
Drag Coefficient ◽  
Unmanned Aerial Vehicles ◽  
Drag Force ◽  
Aerodynamic Drag ◽  
Experimental Characterization ◽  
Aerial Vehicles ◽  
Flat Type ◽  
Suspension Line ◽  
The Impact

Parachute recovery systems are proved to be an efficient method to recovery and rescue unmanned aerial vehicles (UAV) as it follows most requirements of reliability and airworthiness in flights. Parachutes are key components of the recovery systems and the drag coefficient of parachutes plays a crucial role in evaluating parachute’s performance. The purpose of the research is to determine and compare the impact of some factors on aerodynamic drag force during the inflation of a parachute. The canopy’s shape (flat circular type and extended skirt 10% flat type), of the length of suspension lines (be in proportion to nominal diameter from 0.6 to 1.5) are considered. Measurement of the drag force of the parachute models is carried out in an open return wind tunnel. Experimental results show that flat circular canopy has a higher drag coefficient than extended skirt 10% flat model in the range of low speed from 3 to 6 m/s. However, when wind speed is greater than 6 m/s, the drag coefficients of both two parachute types are nearly 0.85. In terms of the suspension line, the longer length would significantly raise the coefficient of drag force.

scholarly journals Experimental Study of the Aerodynamics of Sail in Natural Wind

2018 ◽  
Vol 25 (s2) ◽  
pp. 17-22
Author(s):  
Zeng Xiangming ◽  
Zhang Huawu
Keyword(s):  
Experimental Study ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Wind Field ◽  
Effectiveness Evaluation ◽  
Wind Tunnel Tests ◽  
The Impact ◽  
Natural Wind

Abstract In order to evaluate the impacts of a motor vessel after installing wind sails, the aerodynamics of the sail should be accurately calculated. However most of the research on sails are based on stable wind instead of natural wind which is changing horizontally and vertically. In this paper wind tunnel tests are carried out based on stable wind field and simulated natural wind field, the results shown that there are 16–44% decrease in natural wind in terms of lifting coefficient and 11–42% decrease for drag coefficient. This would provide a valuable reference to the effectiveness evaluation of the impact of sails for sail assisted ships.

scholarly journals Normal and Tangential Drag Forces of Nylon Nets, Clean and with Fouling, in Fish Farming. An Experimental Study

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2238
Author(s):  
Yarko Niño ◽  
Kevin Vidal ◽  
Aldo Tamburrino ◽  
Luis Zamorano ◽  
Juan Felipe Beltrán ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Drag Force ◽  
Fish Farming ◽  
Operating Conditions ◽  
Relevant Parameter ◽  
Sea Lion ◽  
Drag Coefficients ◽  
Average Value ◽  
Drag Forces

Experiments in a laboratory tank have provided measurements of the normal and tangential drag forces exerted on flat nets for different flow conditions. From those forces, normal and tangential drag coefficients of the nets have been obtained as functions of the Reynolds number and the solidity index. The experiments used two types of nets employed in the operation of a cultivation center: the fish net and the sea lion net, for the clean situation and for real operating conditions, with fouling adhered to the nets. Polyethylene ropes were used to characterize the presence of fouling in the nets. The experiments were carried out to determine equations for the normal and tangential drag coefficients. For the normal drag coefficient, the equations are linear with the Reynolds number, and the coefficients of the equations are linear with the solidity index. The equations are not so accurate for the tangential drag coefficient. The Reynolds number is not a relevant parameter for this coefficient and neither is the solidity index for the fish net, but the coefficient grows slightly with it for single and double sea lion nets with fouling. The literature review on the drag forces of nets reports that the tangential drag force is around 30% of the normal drag force. This value is approximately an average value of the ratio for the sea lion net and is higher for the clean fish net in this article.

Lift and Drag Forces With Respect to Azimuth Position of a Darrieus Wind Turbine

2018 ◽  
Author(s):  
Sajid Ali ◽  
Sang-Moon Lee ◽  
Choon-Man Jang
Keyword(s):  
Wind Turbine ◽  
Drag Force ◽  
Lift Force ◽  
Tangential Force ◽  
Navier Stokes ◽  
Drag Forces ◽  
Force Variation ◽  
Lift And Drag ◽  
Naca 0015 ◽  
The Impact

Tangential force is the most important parameter for driving the blade of a straight bladed H-Darrieus wind turbine forward. The direction of this force is very critical as it may move the blade forward (positive force) or it can also oppose the rotation (negative force). The direction of tangential force depends upon the distribution of two fundamental aerodynamic forces around the wind turbine blade i.e. Lift and drag. Current study aims to understand the impact of lift and drag forces on the tangential force variation with respect to (w.r.t) azimuth position. Commercial CFD software SC/tetra was employed in order to solve the unsteady Reynold-averaged Navier stokes (URANS) equations around the blades. Results show that very small portion (maximum 20% during rotation) of the drag force is actually converted into useful tangential force whereas rest of the drag force is converted into either normal force or negative tangential force (waste of energy). On the other hand, out of all the generated lift force, 70–90 percent is seemed to be beneficial for moving the blade forward and rest of the lift force also tries to oppose the motion (almost 15%). Overall, it was found that only 50–60 percent of the resultant force (lift + drag) acting on the blade, is actually useful to move the blade forward. The study was conducted at seven different tip speed ratios (TSRs) i.e. 1, 2, 2.28, 3, 3.5, 4 and 5 with NACA 0015 airfoil. Relatively higher fluctuations were observed in the distribution of forces at low values of TSRs (1 and 2) as compared to high values of TSRs (4 and 5). The results presented here are only limited to NACA 0015 whereas same methodology can be adopted for other blade profiles in future as well.

Theory for the Determination of Flutter Speed of a Class of Hydrofoils

1972 ◽  
Vol 94 (1) ◽  
pp. 76-80 ◽  
Author(s):  
J. Mahig
Keyword(s):  
Experimental Study ◽  
Drag Coefficient ◽  
Constant Speed ◽  
Flutter Speed ◽  
Drag Forces ◽  
Lift Curve ◽  
Theoretical Results

A theory is given for the determination of the flutter frequency and speed of a hydrofoil traveling at a constant speed. This work used the work of Sears to determine the fluctuating lift and combined it with the chordwise and transverse drag forces to determine flutter speeds. It is shown that flutter speed is sensitive to the drag coefficient as well as lift curve slopes. The theoretical results obtained are shown compared with an experimental study conducted by Huang.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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