THERMOTECHNICAL CALCULATIONS OF TWO-DIMENSIONAL TEMPERATURE FIELDS IN POLYMER COMPOSITE STRUCTURES WITH INTUMESCENT FIRE PROTECTION

2013 ◽  
Vol 22 (8) ◽  
pp. 42-47
Author(s):  
V. P. RUDZINSKIY ◽  
◽  
A. N. GARASHCHENKO ◽  
N. A. GARASHCHENKO ◽  
◽  
...  
2021 ◽  
Vol 29 (6) ◽  
pp. 28-39
Author(s):  
A. N. Garashchenko ◽  
A. V. Vinogradov ◽  
I. Z. Dashtiev ◽  
N. V. Kobylkov ◽  
S. A. Terekhov

Introduction. Coiled MBOR basalt fiber material is used to demonstrate the potential of research into the fire protection of structures using a radiant heat test facility. Research methods. A set of high-power halogen lamps is used to simulate a high temperature impact. The heating intensity is adjusted by changing the voltage applied to the lamps, and it is controlled by the thermocouples that record the temperature of the heated surface of a fire proofing material. The studies have proven efficient for various types of fire proofing and various structures. They are especially relevant in providing rational fire protection of polymer composite structures having relatively low thermal resistance (80…120 °С) due to the fact that they are rarely tested in fired furnaces. Results and discussion. Several options of multilayered MBOR-20F fire proofing were tested. Dependences between time, on the one hand, the surface temperature of protected elements (200 × 300 × 20 mm polyurethane plates), and the temperature between the layers of the fire-proofing material, on the other hand, are presented under standard temperature conditions. Fire protection efficiency improvement by PLAZAS fire-resistant adhesive compound, applied between MBOR layers, is demonstrated. This fireproofing method is applicable not only to metal structures. It demonstrates high fireproofing properties and has a strong potential if applied to fireproof polymer composite structures and products. The measurements, taken by thermocouples in the course of a session of tests, can be used to estimate the thermophysical properties of fireproofing materials exposed to high temperatures, which are rare in most cases, although they are necessary for a thermal analysis. It is demonstrated that similar experiments can also be carried out at nonstandard heating temperatures (for example, when the combustion of fossil fuels is imitated). Conclusions. Experiments, conducted using the radiant heat test facility, and thermal engineering calculations allow to accelerate the selection of the optimal fire protection option and identification of the fireproofing thickness. Moreover, this method allows to reasonably minimize the number of costly fired furnace tests using fullscale samples of fireproofed structures and products.


2019 ◽  
pp. 26-31 ◽  
Author(s):  
V. O. Kaledin ◽  
E. S. Vyachkin ◽  
Е. A. Vyachkina ◽  
O. N. Budadin ◽  
S. O. Kozelskaya

Dynamic temperature fields on the surface of a polymer composite material under the action of an internal heat source are considered. It is shown that the use of thermal control based on the measurement and analysis of the temperature field parameters allows detecting a defect (heat source) in the material and determining its depth and coordinates. The studies have shown the possibility of using thermal control to detect internal defects in products made of polymer composite materials when creating internal heat sources in the vicinity of defects with the use of modern thermograph systems that provide the registration of changing the temperature field of 0.1 deg and higher. The numerical solution using the finite element method and the time difference scheme is in good agreement with the analytical solution when choosing grid steps: the error is reduced to 2.4% already at a distance of three grid steps from the source. It is shown that on the basis of the measurement of the parameters of dynamic temperature fields, it is possible to determine the location of the depth of the defect (internal heating source) and its area coordinates that makes it possible significantly to extend the scope of application of thermal control.


1999 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Maximilian S. Mesquita

Abstract The present work investigates the efficiency of the multigrid numerical method applied to solve two-dimensional laminar velocity and temperature fields inside a rectangular domain. Numerical analysis is based on the finite volume discretization scheme applied to structured orthogonal regular meshes. Performance of the correction storage (CS) multigrid algorithm is compared for different inlet Reynolds number (Rein) and number of grids. Up to four grids were used for both V- and W-cycles. Simultaneous and uncoupled temperature-velocity solution schemes were also applied. Advantages in using more than one grid is discussed. Results further indicate an increase in the computational effort for higher Rein and an optimal number of relaxation sweeps for both V- and W-cycles.


Ultrasonics ◽  
2022 ◽  
Vol 120 ◽  
pp. 106657
Author(s):  
Kaipeng Ji ◽  
Peng Zhao ◽  
Chaojie Zhuo ◽  
Mu Chen ◽  
Jian Chen ◽  
...  

Author(s):  
Zi-Gui Huang ◽  
Yunn-Lin Hwang ◽  
Pei-Yu Wang ◽  
Yen-Chieh Mao

The excellent applications and researches of so-called photonic crystals raise the exciting researches of phononic crystals. By the analogy between photon and phonon, repetitive composite structures that are made up of different elastic materials can also prevent elastic waves of some certain frequencies from passing by, i.e., the frequency band gap features also exist in acoustic waves. In this paper, we present the results of the tunable band gaps of acoustic waves in two-dimensional phononic crystals with reticular band structures using the finite element method. Band gaps variations of the bulk modes due to different thickness and angles of reticular band structures are calculated and discussed. The results show that the total elastic band gaps for mixed polarization modes can be enlarged or reduced by adjusting the orientation of the reticular band structures. The phenomena of band gaps of elastic or acoustic waves can potentially be utilized for vibration-free, high-precision mechanical systems, and sound insulation.


1998 ◽  
Vol 4 (2) ◽  
pp. 73-90 ◽  
Author(s):  
Peter Vadasz ◽  
Saneshan Govender

The stability and onset of two-dimensional convection in a rotating fluid saturated porous layer subject to gravity and centrifugal body forces is investigated analytically. The problem corresponding to a layer placed far away from the centre of rotation was identified as a distinct case and therefore justifying special attention. The stability of a basic gravity driven convection is analysed. The marginal stability criterion is established in terms of a critical centrifugal Rayleigh number and a critical wave number for different values of the gravity related Rayleigh number. For any given value of the gravity related Rayleigh number there is a transitional value of the wave number, beyond which the basic gravity driven flow is stable. The results provide the stability map for a wide range of values of the gravity related Rayleigh number, as well as the corresponding flow and temperature fields.


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