THEORETICAL MATHEMATICAL MODELING OF HEAT EXCHANGE  IN PIPES WITH TRIANGULAR AND SQUARE TURBULATORS WITH d/D=0.95÷0.90, t/D=0.25÷1.00 AND HIGH REYNOLDS NUMBERS Re=106

Mathematical modeling of heat exchange process in straight and round horizontal pipes with protrusions and d/D=0.95...0.90, t/D=0.25...1.00 of triangular and square sections with large Reynolds numbers (RE=106) are carried out on the basis of multiblock computing technologies based on solutions of factored and finite-volume algorithm of RANS equations and energy equations. It is shown that for higher square protrusions and at higher Reynolds numbers, a limited increase in NU/NUgl is accompanied by a significant increase in relative hydro resist ance in accordance with the higher Reynolds number; for triangular turbulators, this persists and even deepens.

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Mathematical modeling of the heat-exchange process in a quarry bench in permanently frozen rock

Journal of Mining Science ◽

10.1007/bf02046589 ◽

1996 ◽

Vol 32 (3) ◽

pp. 197-204 ◽

Cited By ~ 1

Author(s):

T. N. Polubelova ◽

V. I. Sleptsov ◽

V. Y. Izakson

Keyword(s):

Mathematical Modeling ◽

Heat Exchange ◽

Exchange Process ◽

Heat Exchange Process

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Mathematical modeling of the heat exchange process transpiration cooling systems under influence of pulsations of a coolant gas

2015 International Conference on Mechanical Engineering, Automation and Control Systems (MEACS) ◽

10.1109/meacs.2015.7414934 ◽

2015 ◽

Author(s):

V.A. Ovchinnikov ◽

A.S. Yakimov

Keyword(s):

Mathematical Modeling ◽

Heat Exchange ◽

Exchange Process ◽

Transpiration Cooling ◽

Cooling Systems ◽

Heat Exchange Process

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Thermic Influence on the Dynamics of Pneumatic Servosystems

Volume 1: Advanced Energy Systems, Advanced Materials, Aerospace, Automation and Robotics, Noise Control and Acoustics, and Systems Engineering ◽

10.1115/esda2006-95545 ◽

2006 ◽

Author(s):

Massimo Sorli ◽

Laura Gastaldi

Keyword(s):

Heat Exchange ◽

Natural Frequency ◽

Working Conditions ◽

Dynamic Stiffness ◽

Exchange Process ◽

Temperature Dynamics ◽

Heat Exchange Process ◽

Energy Equations ◽

And Control ◽

Accuracy And Repeatability

The gains values that can be imposed in pneumatic systems controllers are bounded to the restricted actuator bandwidth. That limitation, with low damping and stiffness, due to the air compressibility, seriously affects accuracy and repeatability when varying payload or supply pressures. For modelling and control intent a correct characterisation of the pneumatic actuator natural frequency is indispensable. The aim of this paper is to evaluate how heat exchange process affects the proper characteristics of pneumatic drivers, and in particular their hydraulic stiffness. To this purpose dynamic stiffness had been studied both by imposing in the cylinder’s chambers a polytrophic transformation of the fluid with a prefixed index and by employing energy equations. Numerical results obtained by implementing the two formulations for different working conditions are reported and compared in order to point out the ranges in which they overlap, and hence both approaches produce accurate results, or the ones in which there is a difference, and then it is necessary to consider the temperature dynamics.

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On cavity flow at high Reynolds numbers

Journal of Fluid Mechanics ◽

10.1017/s0022112077000214 ◽

1977 ◽

Vol 79 (2) ◽

pp. 391-414 ◽

Cited By ~ 87

Author(s):

M. Nallasamy ◽

K. Krishna Prasad

Keyword(s):

Reynolds Numbers ◽

Separated Flows ◽

Navier Stokes ◽

Thermal Fields ◽

High Reynolds Numbers ◽

Wide Range ◽

High Reynolds ◽

Energy Equations ◽

First Time ◽

Finite Difference Techniques

The flow in a square cavity is studied by solving the full Navier–Stokes and energy equations numerically, employing finite-difference techniques. Solutions are obtained over a wide range of Reynolds numbers from 0 to 50000. The solutions show that only at very high Reynolds numbers (Re[ges ] 30000) does the flow in the cavity completely correspond to that assumed by Batchelor's model for separated flows. The flow and thermal fields at such high Reynolds numbers clearly exhibit a boundary-layer character. For the first time, it is demonstrated that the downstream secondary eddy grows and decays in a manner similar to the upstream one. The upstream and downstream secondary eddies remain completely viscous throughout the range of Reynolds numbers of their existence. It is suggested that the behaviour of the secondary eddies may be characteristic of internal separated flows.

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