[en] This report contains a short resume of the available information from various sources on the effect of free convection flow on forced convection heat transfer in vertical channels. Both theoretical and experimental investigations are included. Nearly all of the theoretical investigations are concerned with laminar flow with or without internal heat generation. More consistent data are available for upward flow than for downward flow. Curves are presented to determine whether free convection or forced convection mode of heat transfer is predominant for a particular Reynolds number and Rayleigh number. At Re_b > 10⁵ free convection effects are negligible. Downward flow through a heated channel at low Reynolds number is unstable. Under similar conditions the overall heat transfer coefficient for downward flow tends to be higher than that for upward flow

[en] An experimental study was made of turbulent heat transfer from a vertical cylinder placed in a square channel. The flow medium was water flowing upwards. Basic differential equations governing the mixed flow heat transfer phenomena in a vertical annulus are presented. A dimensional analysis is done to find the dimensionless variables affecting the relative magnitude of the effect of buoyancy on forced convection heat transfer. Dimensionless equations correlating the experimental data ana incorporating a buoyancy parameter of the form Gr/Re² are presented. Reynolds number range covered is 690 to 129,500 and the Rayleigh num- ber range covered is 10⁹ to 4.2 x 10¹³ . Effect of different length parameters, like hydraulic diameter and distance of the measuring point from the inlet of the test section, on dimensionless equations are studied

[en] This report contains descriptions of various analogues utilised to study different steady-state and unsteady-state heat transfer problems. The analogues covered are as follows: 1 . Hydraulic: a) water flow b) air flow 2. Membrane 3. Geometric Electrical: a) Electrolytic-tank b) Conducting sheet 4. Network; a) Resistance b) R-C A comparison of the different analogues is presented in the form of a table

[en] This literature survey deals with changes in heat transfer coefficient and friction factor with varying nature and degree of roughness. Experimental data cover mainly the turbulent flow region for both air and water as flow mediums. Semiempirical analysis about changes in heat transfer coefficient due to roughness has been included. An example of how to use these data to design a heat exchanger surface is also cited. The extreme case of large fins has not been considered. Available literature between 1933 - 1963 has been covered

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[en] A variable flow control for a control rod assembly of a nuclear reactor that depends on turbulent friction though an annulus. The annulus is formed by a piston attached to the ocntrol rod drive shaft and a housing or sleeve fitted to the enclosure housing the control rod. As the nuclear fuel is burned up and the need exists for increased reactivity, the control rods are withdrawn, which increases the length of the annulus and decreases the rate of coolant flow through the control rod assembly

[en] The purpose of this paper is to demonstrate a methodology being used in a probabilistic risk assessment of main steam line break outside the containment vessel. An attempt is made to estimate in a systematic manner the consequences and probabilities of the primary event with respect to different operations on the engineered safety systems. By using this methodology the most probable consequences of a given accident are predicted to arrive at a realistic view of the risk distribution. The spectrum of probable consequences will be shown step by step through this analysis. The study begins with a cause- and frequency analysis of the primary event. After stating the accident sequences one must estimate the reliability of the engineered safety systems in the different sequences. This calculation is briefly presented in the report. The safety systems in consideration consists mainly of the core spray system, the reactor containment vessel, the reactor building ventilation and filter system. The consequences of the given accident are combined with the probability of its occurrence. This approach gives a good understanding of the distribution of the possible consequences. The result of the analysis is presented in a tabular form. The calculations and the results in the report are based on reliability theory and data available in literature

[en] Ionospheric amplitude and phase scintillation data have been analyzed to estimate the information dimension associated with the attractor of the system. For weak scintillations, both amplitude and phase data yield identical results which demonstrate that spatial fluctuations of electron density in the ionosphere may be characterized by a few degrees of freedom. Stronger scintillations are attributed to steepened density irregularities which cause focusing of the incident radio wave. This results in the amplitude scintillations exhibiting higher dimensional chaos but spatial fluctuations in ionospheric density still involve low dimensional chaos

No abstract available

No abstract available