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RESEARCH PAPERS

J. Eng. Power. 1972;94(1):1-10. doi:10.1115/1.3445613.

Models of single throws of overlapped crankshafts have been loaded by free and restrained torsion, radial and tangential forces and bending moments, and by axial tension. Stress distributions in the fillets have been obtained by frozen stress photoelasticity. Some peak stresses have been measured with strain gauges. Results, expressed as multiples of convenient nominal stresses, are compared with predictions from published work. The maximum stresses due to any combination of firing force and free torsion were computed and it is shown how the effects of other loading modes may be included.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1972;94(1):11-14. doi:10.1115/1.3445608.

This paper is pertinent mainly to combustion in open-chamber diesel engines employing air swirl. It is shown how an increase in air swirl rate can cause a marked loss of combustion efficiency unless fuel spray penetration is increased. High swirl reduces radial fuel spray penetration with central injection and the resulting excess fuel in the central area may be trapped by buoyancy forces following ignition, becoming isolated for as much as a tenth of a second in a chamber of four in. diameter. A brief explanation of fuel injection in terms of the mechanics of fluid jets is given and circumstances described in which buoyancy forces assist fuel-air mixing following ignition.

Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
J. Eng. Power. 1972;94(1):24-34. doi:10.1115/1.3445614.

The electrodynamic shaker is a useful tool in the evaluation and development of engine components and accessories. As the shaker vibratory input to the component fixture or the engine assembly is controlled, the vibratory response of the component or accessory can be determined. A brief review of vibration theory and vibration response of several simple mechanical elements is included. Three examples of the development of engine components by use of fatigue fixtures and three examples of evaluation of engine mounted accessories are presented.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1972;94(1):35-41. doi:10.1115/1.3445616.

An experimental study of the effects of a cross-flowing air stream on the heat transfer characteristics of single lines of circular air jets impinging on plane surfaces is presented. The study models a practically important class of cooling configurations where jets issuing from one wall of a channel and impinging on the opposite wall are deflected by the exhausting flow of upstream jets. The upstream and downstream changes in heat transfer are evaluated separately and compared with heat transfer rates obtained in the absence of crossflow.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1972;94(1):43-50. doi:10.1115/1.3445619.

In this report, a method of analyzing steady, three-dimensional, subsonic, nonviscous flow through a turbomachine with arbitrary hub and shroud shapes and with a finite number of blades is presented. In order to make the analysis manageable, the stream surfaces are assumed to be axisymmetric. Position and shape of these surfaces, which depend upon the work of blades, are obtained by a meridional plane solution using a quasi-orthogonal coordinate system. The flow condition on these surfaces of revolution and the work of blades are obtained by a new blade-to-blade solution and the results are used to improve the meridional plane solution. This procedure is repeated until solution converges. Some numerical examples are given.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1972;94(1):51-58. doi:10.1115/1.3445620.

An experimental investigation of heat transfer characteristics for various configurations of air jets impinging on the leading edge inner surface of the blade wall is presented. Three configurations were investigated, namely a slot jet, a round jet row and an array of round jets. The effect on the heat transfer coefficient of injecting solid particles into the air flow is considered. The study treats an important class of turbine blade cooling for which small cooling mass flow rates are of interest. The experimental facility and procedures are described in detail. A theoretical technique is introduced for predicting the heat transfer in the case of the slot jet configuration. The results are compared to experimental data.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1972;94(1):61-68. doi:10.1115/1.3445623.

In an effort to reduce engine length and weight it is desirable in some applications, such as high bypass ratio turbofan engines, to introduce compressor stages into a downward sloping flowpath. In this “mixed flow” compressor the airfoil orientation with respect to the flowpath becomes important to ensure good performance. The performance of cascades and compressor stages with sloping walls is presented. Three methods of introducing blading into the flowpath were evaluated. It is shown that by canting the blading to be normal to the flow direction, no penalty in performance is incurred compared to the performance of a typical axial compressor with cylindrical flowpath. Test results are compared with predictions based on intrablade analysis and a wall boundary layer calculation. Qualitatively good agreement is obtained except for the case when the blading is swept with respect to the flow direction. Need for further investigtion of three dimensional internal viscous flows is indicated.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

Commentary by Dr. Valentin Fuster

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