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RESEARCH PAPERS

J. Eng. Power. 1969;91(3):143-147. doi:10.1115/1.3574710.

A resonant beam tuned damping device, comprising a flexible beam joined by way of visco-elastic links at the ends, to a vibrating structure, is described. This device has the advantage of relying on the interaction between the beam stiffness and the link stiffness for tuning, rather than on the link stiffness alone as for the conventional tuned damper, so that a weight-saving potential exists. An analysis is developed and verified experimentally.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1969;91(3):149-155. doi:10.1115/1.3574713.

An experimental study of the heat transfer characteristics between single lines of circular jets and concave cylindrical surfaces is presented. It is intended to model a practically important class of impingement cooling configurations for which existing heat transfer correlations are not obviously applicable. The results clarify the present uncertain position with regard to the optimum spacing between the jet nozzle and the heat transfer surface and with regard to the center-to-center spacing between the jets. Some limited results for a two-dimensional jet impinging on the concave surfaces are also presented.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1969;91(3):159-170. doi:10.1115/1.3574718.

This paper presents a method of tailoring the regenerative feedwater-heating system in a nuclear plant to the availability of extraction openings on the main turbine. This is accomplished by optimizing the heater design conditions of each individual heater, in conformance with the peculiarities of the particular cycle being used, and the evaluation parameters that are applicable. It is shown by example that for a typical six-heater, reheat nuclear plant the evaluation is improved. The results show that such “total optimization” in an 880 Mwe plant will accomplish: 1 - An improvement of 27 Btu/kwhr in heat rate, 2 - An increase of 2500 kw in net output (at constant reactor thermal power), 3 - An increase of about 18.5 percent in heater surface, in the reference cycle, for the selected values of the heat rate and incremental kw evaluation parameters, and heater surface cost of $10/sq ft. However, if an incremental heater cost is used, say $6/sq ft, optimum evaluation yields: 1 - An improvement of 45.3 Btu/kwhr in heat rate, 2 - An increase of 4200 kw in net output (at constant reactor thermal power), 3 - An increase of about 42 percent in heater surface. For this set of conditions, there is an improvement in evaluation of about $300,000 for the 880 Mwe plant.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1969;91(3):173-180. doi:10.1115/1.3574723.

Alkali iron trisulfates have been recognized as a major contributor to corrosion of super-heater lubes of boiler furnaces. Factors effecting formation of trisulfate were studied in an oil-fired laboratory combustor that simulates a boiler-furnace environment. Catalysis of SO2 to SO3 by fly ash to produce the high SO3 concentrations necessary for stability of trisulfates at superheater temperatures was investigated. Effects of deposit composition, deposit thickness, temperature, and SO3 concentration on formation of trisulfates were examined.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1969;91(3):182-187. doi:10.1115/1.3574726.

Intercoupling between blades mounted on a flexible disk is examined employing a lumped-parameter model incorporating damping. Tests carried out on a gas turbine compressor and blades provide frequency and mass parameters for the model. Analysis of the model shows that vibration, and hence stress, in one or more blades, can be magnified if the distribution of blade natural frequency around the disk is suitably chosen. Feasible distributions are examined, leading to stress increases of up to 180 percent.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1969;91(3):189-197. doi:10.1115/1.3574731.

A quasisteady method for measuring the thermal diffusivity of molten salts at temperatures above their melting point is described. Essentially, the difference between the temperature at the surface and at the center of a cylindrical container is measured for a constant rate of surface temperature rise. The liquid, whose thermal diffusivity is to be measured, is contained in a narrow annular groove concentric with the surface. The advantages of this method are: (a) no heat flux measurements are needed; (b) no liquid temperature need be measured; (c) theoretically assumed boundary conditions can be experimentally realized; (d) absence of convection can be experimentally verified. Results of measurements are reported for liquid lithium fluoride and sodium nitrate. The results for sodium nitrate agree with previously published results. The thermal conductivity of lithium fluoride can be empirically expressed in terms of the melting point, the molecular weight and the density, as

k = 0.9Tm1/2ρm2/3M−7/6

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1969;91(3):198-205. doi:10.1115/1.3574732.

Metal surfaces exposed to combustion gases from residual fuels suffer from fouling and severe corrosion. Several methods currently in use to combat these effects include chemical treatment of the fuel, combustion at near stoichiometric conditions, and the use of protective coatings. This study introduces another method based primarily on improved burner technology, specifically, combustion with massive, external recirculation. Short (10-hr) and long (30-hr) exposure time tests have demonstrated that the combustion of untreated oil having a high vanadium and sodium content with sufficiently large recirculation produces corrosion of essentially the same magnitude as that experienced from the combustion of diesel fuel without recirculation. These beneficial effects of recirculation are greatest at conditions giving rise to highest corrosion rates, i.e., at high excess air and high metal temperature.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1969;91(3):207-215. doi:10.1115/1.3574737.

Thermal transpiration, the phenomenon of the flow of gases through porous media under the influence of a temperature gradient, can be utilized as a driving force in a new type of gas pump. A parametric study for determining conditions for the optimum performance of such a pump requires, in addition to the thermal transpiration measurements, appropriate independent measurements for determining the geometric properties of the porous media. Experiments were carried out on five porous ceramics and two Millipore fillers of different geometric properties. It was found that a maximum reduced efficiency of about 1 percent can be achieved with a thermal pump under optimum conditions. Equations based on the methods of nonequilibrium thermodynamics and the dusty-gas theory satisfactorily explain the experimental results and thus allow the prediction of pump performance for given conditions.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1969;91(3):216-220. doi:10.1115/1.3574738.

Radioactive sulfur-35 has been used as a tracer to determine the roles of SO2 and SO3 in reactions leading to formation of alkali iron trisulfates. The reactivity of 30 ppm SO3 with surfaces containing iron oxides, alone or mixed with alkali sulfates, has been found to be much greater than that of large amounts of SO2 + O2 over the temperature range 900 to 1300 deg F. The SO3 reactivity was found to be a maximum at 1200 deg F, while the SO2 reactivity was at a minimum about 1150 deg F. Complex sulfates were formed most readily with K2 SO4 -Fe2 O3 surfaces, followed by Na2 SO4 -steel, and Na2 SO4 -Fe3 O3 surfaces.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

Commentary by Dr. Valentin Fuster

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