Time Dependent Effect of flow properties on addition of heat to the air flow at Compressible Subsonic Speeds

Heat addition process is a governing phenomenon in turbojet and ramjet burners, where heat is added to the flow during the fuel-air combustion process. In the present work, an analytical study has been performed to investigate the effect of heat addition on the basic flow properties based on compressible Rayleigh flow model between the subsonic and sonic flow regime. The unsteady nature of flow properties in these regimes have been evaluated analytically by adding heat through the walls of a constant area, frictionless duct in which air flow occurs over different periods of time. Sudden variation of temperature, pressure, velocity and kinetic energy of the flow were found at flow Mach number M = 0.94. Flow velocity and kinetic energy increases until the flow approaches M = 0.94, afterwards there is a rapid increase in the flow velocity and kinetic energy until it reaches sonic conditions. Conversely, pressure decreased till the flow reaches M = 0.94, there after a sudden drop was observed. Flow enthalpy increased initially, reached maximum at flow M = 0.845 and then reduced till sonic conditions. Based on the observations, it has been concluded that the heat energy contributed to increase the kinetic energy thereby reducing the temperature of the flow.

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Improving the efficiency of carousel wind turbine using aerodynamic shield

Journal of Physics Conference Series ◽

10.1088/1742-6596/2119/1/012093 ◽

2021 ◽

Vol 2119 (1) ◽

pp. 012093

Author(s):

A F Serov ◽

V N Mamonov ◽

A D Nazarov ◽

N B Miskiv

Keyword(s):

Kinetic Energy ◽

Flow Velocity ◽

Air Flow ◽

Cylindrical Body ◽

Vertical Axis ◽

Rotor Blades ◽

Heat Generator ◽

Axis Of Rotation ◽

Wheel Torque ◽

Air Flow Velocity

Abstract The problem of increasing the efficiency of using the oncoming air flow for a wind wheel with a vertical axis of rotation, which is a mechanical drive of the wind heat generator, is considered. It is proposed to increase the efficiency of the device by installing an aerodynamic shield for the air flow oncoming the wind wheel. Such a shield is a cylindrical body in which a heat generator is placed. The shield creates an effect of confuser, leading to an increase in the speed and, consequently, in the kinetic energy of the air flow acting on the rotor blades. It is shown experimentally that the presence of an aerodynamic shield under the conditions of the experiments carried out at an incoming air flow velocity of ~ 1 m/s leads to a practical doubling of the wind wheel torque.

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EXPERIMENTAL AND ANALYTICAL STUDIES OF VERTICAL AXIS WIND TURBINES

Alternative Energy and Ecology (ISJAEE) ◽

10.15518/isjaee.2018.22-24.051-058 ◽

2018 ◽

pp. 51-58

Author(s):

B. P. Khozyainov

Keyword(s):

Wind Turbine ◽

Flow Velocity ◽

Wind Power ◽

Wind Turbines ◽

Power Efficiency ◽

Air Flow ◽

Geometrical Parameters ◽

Wind Speeds ◽

Analytical Studies ◽

Air Flow Velocity

The article carries out the experimental and analytical studies of three-blade wind power installation and gives the technique for measurements of angular rate of wind turbine rotation depending on the wind speeds, the rotating moment and its power. We have made the comparison of the calculation results according to the formulas offered with the indicators of the wind turbine tests executed in natural conditions. The tests were carried out at wind speeds from 0.709 m/s to 6.427 m/s. The wind power efficiency (WPE) for ideal traditional installation is known to be 0.45. According to the analytical calculations, wind power efficiency of the wind turbine with 3-bladed and 6 wind guide screens at wind speedsfrom 0.709 to 6.427 is equal to 0.317, and in the range of speed from 0.709 to 4.5 m/s – 0.351, but the experimental coefficient is much higher. The analysis of WPE variations shows that the work with the wind guide screens at insignificant average air flow velocity during the set period of time appears to be more effective, than the work without them. If the air flow velocity increases, the wind power efficiency gradually decreases. Such a good fit between experimental data and analytical calculations is confirmed by comparison of F-test design criterion with its tabular values. In the design of wind turbines, it allows determining the wind turbine power, setting the geometrical parameters and mass of all details for their efficient performance.

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Ways to improve the accuracy of measuring the air flow velocity of the acoustic anemometer

MINING INFORMATIONAL AND ANALYTICAL BULLETIN ◽

10.25018/0236-1493-2019-5-14-3-12 ◽

2019 ◽

Vol 5 (14) ◽

pp. 3-12

Author(s):

S.Z. Shkundin ◽

◽

D.S. Belikov ◽

Keyword(s):

Flow Velocity ◽

Air Flow ◽

Acoustic Anemometer ◽

Air Flow Velocity

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Development of a two zone turbulence model and its application to the cycle-simulation

Thermal Science ◽

10.2298/tsci130103030s ◽

2014 ◽

Vol 18 (1) ◽

pp. 1-16 ◽

Cited By ~ 10

Author(s):

Momir Sjeric ◽

Darko Kozarac ◽

Rudolf Tomic

Keyword(s):

High Pressure ◽

Kinetic Energy ◽

Flow Field ◽

Turbulent Kinetic Energy ◽

Turbulence Model ◽

Combustion Process ◽

Progress Variable ◽

Cycle Simulation ◽

Pressure Cycle ◽

Turbulent Flow Field

The development of a two zone k-? turbulence model for the cycle-simulation software is presented. The in-cylinder turbulent flow field of internal combustion engines plays the most important role in the combustion process. Turbulence has a strong influence on the combustion process because the convective deformation of the flame front as well as the additional transfer of the momentum, heat and mass can occur. The development and use of numerical simulation models are prompted by the high experimental costs, lack of measurement equipment and increase in computer power. In the cycle-simulation codes, multi zone models are often used for rapid and robust evaluation of key engine parameters. The extension of the single zone turbulence model to the two zone model is presented and described. Turbulence analysis was focused only on the high pressure cycle according to the assumption of the homogeneous and isotropic turbulent flow field. Specific modifications of differential equation derivatives were made in both cases (single and two zone). Validation was performed on two engine geometries for different engine speeds and loads. Results of the cyclesimulation model for the turbulent kinetic energy and the combustion progress variable are compared with the results of 3D-CFD simulations. Very good agreement between the turbulent kinetic energy during the high pressure cycle and the combustion progress variable was obtained. The two zone k-? turbulence model showed a further progress in terms of prediction of the combustion process by using only the turbulent quantities of the unburned zone.

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The influence of voltage and air flow velocity of combined convective-electrohydrodynamic drying system on the kinetics and energy consumption of mushroom slices

Journal of Cleaner Production ◽

10.1016/j.jclepro.2015.02.033 ◽

2015 ◽

Vol 95 ◽

pp. 203-211 ◽

Cited By ~ 21

Author(s):

Somayeh Taghian Dinani ◽

Michel Havet

Keyword(s):

Energy Consumption ◽

Flow Velocity ◽

Air Flow ◽

Drying System ◽

Air Flow Velocity

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Numerical Study of Distribution Temperature and Air Flow Velocity at Closed Type Chicken Coop for Capacity of 15,500 Chicks with Opening 1 Inlet and 4 Exhaust

Universal Journal of Mechanical Engineering ◽

10.13189/ujme.2019.071302 ◽

2019 ◽

Vol 7 (3A) ◽

pp. 12-19

Author(s):

Nia Nuraeni Suryaman ◽

Udin Komaruddin ◽

Arry Hutomo ◽

Dr. Martoni

Keyword(s):

Flow Velocity ◽

Numerical Study ◽

Air Flow ◽

Closed Type ◽

Air Flow Velocity

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Numerical investigation of the effect of the turbulence in the predicting flow velocity distribution, turbulence kinetic energy and hydrostatic pressure on the lateral intakes

Journal of Vibroengineering ◽

10.21595/jve.2015.15924 ◽

2016 ◽

Vol 18 (4) ◽

pp. 2429-2436

Author(s):

Edris Merufinia ◽

Adel Asnaashari ◽

Babak Aminnejad ◽

Saeid Khoshtinat

Keyword(s):

Hydrostatic Pressure ◽

Kinetic Energy ◽

Velocity Distribution ◽

Flow Velocity ◽

Numerical Investigation ◽

Turbulence Kinetic Energy

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Numerical Study on the Surface Convective Heat Transfer of Mass Concrete Structure

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.723.992 ◽

2015 ◽

Vol 723 ◽

pp. 992-995

Author(s):

Biao Li ◽

Fu Guo Tong ◽

Chang Liu ◽

Nian Nian Xi

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Flow Velocity ◽

Convective Heat Transfer ◽

Convective Heat ◽

Air Flow ◽

Convective Heat Transfer Coefficient ◽

Concrete Surface ◽

Mass Concrete ◽

Air Flow Velocity

The surface convective heat transfer of mass concrete is an important element of concrete structure temperature effect analysis. Based on coupled Thermal Fluid governing differential equation and finite element method, the paper calculated and analyzed the dependence of the concrete surface convective heat transfer on the air flow velocity and the concrete thermal conductivity coefficient. Results show that the surface convective heat transfer coefficient of concrete is a quadratic polynomial function of the air flow velocity, but influenced much less by the air flow velocity when temperature gradient is dominating in heat transfer. The concrete surface convective heat transfer coefficient increases linearly with the thermal conductivity of concrete increases.

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