Entrance loss coefficients and exit coefficients for a physical model of the glottis with convergent angles

An experimental flow study on cooling holes in cylindrical models simulating the leading edge of a typical turbine airfoil is presented. The effect of external flow around the cylinder on the coolant discharge through a single hole is represented as a function of the momentum ratio of the cooling jet to the local external flow. A similar correlation was found for the effect of internal axial flow. The ability to separate the entrance and exit effects on the hole is due to the fact that the hole is a long orifice. The entrance and exit effects on the coolant flow are expressed as loss coefficients analogous to traditional loss coefficients in pipe flow. The loss coefficients for single holes were used to predict the total and individual flows through an array of holes in the presence of an external flow field. The total flow is predicted accurately as compared to the results of tests on arrays of holes. It can be concluded that the interaction between adjacent cooling holes is slight. The physical model can be used for coolant optimization studies.

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Head Loss Reduction in Surcharged Four-Way Junction Manholes

Water ◽

10.3390/w10121741 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1741 ◽

Cited By ~ 2

Author(s):

Jung Kim ◽

Jun Jo ◽

Sei Yoon

Keyword(s):

Numerical Simulations ◽

Physical Model ◽

Flow Rate ◽

Flow Characteristics ◽

Head Loss ◽

Loss Reduction ◽

Effluent Flow Rate ◽

Loss Coefficients ◽

Drainage Capacity ◽

Influent Flow

Head loss in surcharged four-way junction manholes is a factor that increases damage due to urban inundation; thus, the flow characteristics of such manholes must be analyzed to reduce the head loss. In this study, a physical model was constructed; this model included a manhole and a connection pipe, fabricated on a 1/5 scale by applying sewer facility standards to perform a physical model investigation. Numerical simulations were performed using the Fluent model to derive efficient benching designs that can reduce head loss. Physical model investigations were performed by varying the ratio of the lateral influent flow rate to the effluent flow rate as well as by varying the effluent flow rate and benching designs. The result of physical model investigations showed that the installation of half rectangular benching reduced the head loss coefficients by 7% and 10% on average compared with square and circular manholes, respectively. The installation of full rectangular benching reduced the head loss coefficients by 28% and 17% on average compared with square and circular manholes, respectively. Thus, the benching proposed herein can be installed and used to improve the drainage capacity of urban stormwater conduit facilities.

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Intraglottal pressures in a static physical model of the uniform glottis: Entrance loss coefficients and viscous effects

The Journal of the Acoustical Society of America ◽

10.1121/1.2942789 ◽

2007 ◽

Vol 122 (5) ◽

pp. 3019 ◽

Cited By ~ 2

Author(s):

Lewis Fulcher ◽

Ronald Scherer

Keyword(s):

Physical Model ◽

Viscous Effects ◽

Loss Coefficients

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EXPERIMENTAL STUDIES OF CAR PROPERTIES ON A PHYSICAL MODEL

Avtoshliakhovyk Ukrayiny ◽

10.33868/0365-8392-2019-4-260-10-16 ◽

2019 ◽

pp. 10-16

Author(s):

Oleksii Timkov ◽

Dmytro Yashchenko ◽

Volodymyr Bosenko

Keyword(s):

Mathematical Model ◽

Remote Control ◽

Physical Model ◽

Model Experiment ◽

Experimental Studies ◽

Electrical Energy ◽

Short Term ◽

Motor Current ◽

Memory Card ◽

The Mathematical Model

The article deals with the development of a physical model of a car equipped with measuring, recording and remote control equipment for experimental study of car properties. A detailed description of the design of the physical model and of the electronic modules used is given, links to application libraries and the code of the first part of the program for remote control of the model are given. Atmega microcontroller on the Arduino Uno platform was used to manage the model and register the parameters. When moving the car on the memory card saved such parameters as speed, voltage on the motor, current on the motor, the angle of the steered wheel, acceleration along three coordinate axes are recorded. Use of more powerful microcontrollers will allow to expand the list of the registered parameters of movement of the car. It is possible to measure the forces acting on the elements of the car and other parameters. In the future, it is planned to develop a mathematical model of motion of the car and check its adequacy in conducting experimental studies on maneuverability on the physical model. In addition, it is possible to conduct studies of stability and consumption of electrical energy. The physical model allows to quickly change geometric dimensions and mass parameters. In the study of highway trains, this approach will allow to investigate the various layout schemes of highway trains in the short term. It is possible to make two-axle road trains and saddle towed trains, three-way hitched trains of different layout. The results obtained will allow us to improve not only the mathematical model, but also the experimental physical model, and move on to further study the properties of hybrid road trains with an active trailer link. This approach allows to reduce material and time costs when researching the properties of cars and road trains. Keywords: car, physical model, experiment, road trains, sensor, remote control, maneuverability, stability.

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