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RESEARCH PAPERS

J. Eng. Power. 1978;100(2):197-202. doi:10.1115/1.3446333.

The detailed aerodynamic design and test verification of a 6000-hp (4474-kW) turbine with a supersonic first stage for an airborne application is described. The 12.3-in. (312.4-mm) pitch diameter turbine is driven by products of hydrazine decomposition at 700 psia (4.826 MPa) and 2110 R (1172 K) with an overall pressure ratio of 41.2. The design of the supersonic nozzles and rotor incorporated improved concepts compared to previously reported designs. Test results show that the predicted performance was verified. The supersonic design concepts described are applicable to other high-pressure ratio designs where maximum efficiency is required.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):203-211. doi:10.1115/1.3446335.
Abstract
Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):212-218. doi:10.1115/1.3446336.

The development of a streamline curvature throughflow program to predict the flow through the low pressure stages of large steam turbines is described. The program can also be used for gas turbines. Difficulties encountered in dealing with transonic flow and multiple high pressure ratio stages are discussed. Comparisons of the predictions of the program with flow measurements in steam and gas turbines show reasonably good agreement with most of the discrepancies being attributable to errors in the empirical data input to the program.

Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):229-234. doi:10.1115/1.3446338.
Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):235-240. doi:10.1115/1.3446339.

Numerous unexplained failures of rotating machinery by nonsynchronous shaft whirling point to a possible driving mechanism or source of energy not identified by previously existing theory. A majority of these failures have been in machines characterized by overhung disks (or disks located close to one end of a bearing span) and/or high power and load torque. This paper gives exact solutions to the nonlinear differential equations of motion for a rotor having both of these characteristics and shows that high ratios of driving torque to damping can produce nonsynchronous whirling with destructively large amplitudes. Solutions are given for two cases: (1) viscous load torque and damping, and (2) load torque and damping proportional to the second power of velocity (aerodynamic case). Criteria are given for avoiding the torquewhirl condition.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):241-251. doi:10.1115/1.3446340.

The influence of the back pressure on the diffusion of mass and momentum of the fuel in the diesel spray is investigated and reported in this paper. Analytical models were proposed to depict the similarity profiles for the distribution of velocity and mass of the fuel in the diesel spray injected into stagnant atmosphere maintained at different back pressures and ambient temperature. It is conclusively shown that the proposed models are superior to Abramovich and Albertson models so far as the spray situation is concerned. The Schmidt number, σf , varied from 0.806 to 0.430 when the injection pressure was varied from 100 to 200 atm and the back pressure from 1 to 10 atm. It is confirmed that mass diffuses faster than the momentum, the rate of diffusion increasing with the increase in injection pressure and the back pressure.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):252-259. doi:10.1115/1.3446341.

The desire to establish an efficient Energy Conversion System to utilize the fossil fuel of the future—coal—has produced many candidate systems. A comparative technical/economic evaluation was performed on the seven most attractive advanced energy conversion systems. The evaluation maintains a cycle-to-cycle consistency in both performance and economic projections. The technical information base can be employed to make program decisions regarding the most attractive concept. A reference steam power plant was analyzed to the same detail and, under the same ground rules, was used as a comparison base. The power plants were all designed to utilize coal or coal-derived fuels and were targeted to meet an environmental standard. The systems evaluated were two advanced steam systems, a potassium topping cycle, a closed cycle helium system, two open cycle gas turbine combined cycles, and an open cycle MHD system.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):260-266. doi:10.1115/1.3446342.

A central problem in attempting to use ceramic materials in demanding structural applications is uncertainty about the stresses to which they can be safely subjected. A ceramic rarely, if ever, exhibits a characteristic failure stress. This stress depends on the nature and distribution of microscopic flaws that intensify stress locally, and fracture initiates at a single “worst” flaw when Griffith’s criterion for crack instability is met. Within the basic framework, theories are available for treating effects of time, size, and stress distribution on failure stress. This paper reviews these theories, and discusses their use in specifying limiting stresses in designing structural members.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):267-278. doi:10.1115/1.3446343.

The pollution problems associated with unburned hydrocarbons and carbon monoxide in the idle mode, and NOx and smoke production in the power mode of aircraft gas turbine operation can be minimized using hybrid catalytic combustion. A hybrid catalytic combustor (HCC) consists of a fuel-rich precombustor, secondary air quenching zone, and monolithic catalyst stage which rapidly oxidizes CO and UHC produced in the precombustor. The concentration of thermally produced NOx in the precombustor is very low because of the lack of oxygen. However, the formation of NOx precursors such as HCN and NH3 produced under fuel rich conditions must be considered. Data showed that nitrogenous species produced in the rich precombustion zone were efficiently converted to NOx by catalysts under very lean mixture conditions. The equivalence ratio in the precombustor was varied from 0.5 to 1.5, while the overall mixture, after secondary air injection, was in the range of 01–0.3. The noble metal catalysts on various monolithic support geometries and compositions were found to be the most active materials for CO and UHC oxidation in the temperature range of 700–1200 K. The HCC combustion efficiency of JP-4 which contained 535-ppm sulfur was determined to be 99.8 percent under realistic conditions. The combustor pressure drop was less than 6 percent. The average emission indices of CO, UHC, and NOx leaving the HCC were on the order of 0.95, 0.43, and 1.8 g/kg of fuel, respectively, for metal supported Pt catalyst. This catalyst was effective in reducing CO by 86 percent and UHC by 94 percent, and increasing NOx by 68 percent. Using approximate methods for calculating EPA emission parameters, it was estimated that the HCC can meet the 1979 new aircraft emission standards but fails to meet the 1981 new aircraft emission standards because UHC are slightly too high.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):279-286. doi:10.1115/1.3446344.

The flow field ahead, within, and behind the rotor of a transonic axial compressor designed for a total pressure ratio of 1.51 at a relative tip Mach number of 1.4 has been studied in detail using an advanced laser velocimeter. The tests were carried out at 70 and 100 percent design speed (20,260 rpm) and equivalent mass flows corresponding to the point of maximum isentropic efficiency. The tests yielded quite complete data on the span- and gap-wise velocity profiles, on the three-dimensional shock waves in and outside of the rotor blade channels, and on the blade wakes. Some of the experimental results will be submitted, discussed, and compared to corresponding analytical data of a through-flow calculation. The comparison reveals considerable discrepancies inside the blade row between the two-dimensional calculation and the experiments primarily due to the loss and deviation correlations used, as well as to the distribution of losses and flow angles inside the blade channels.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):287-292. doi:10.1115/1.3446346.

The boundary layer on an axial-flow compressor stator blade has been measured using an ensemble-averaging technique. Although the mean velocity profiles appear to indicate fully developed turbulent flow, ensemble-averaged instantaneous profiles show the boundary layer to be highly unsteady and transitional over much of the blade chord. At a given chordwise position, variations in boundary-layer thickness with time of up to 150 percent were recorded. When compared to boundary-layer development on a similar blade in a two-dimensional cascade the stator blade boundary-layer growth was found to be much greater. The results indicate that extreme caution should be used in attempting to predict blade boundary-layer development from cascade test results or steady calculation procedures.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):294-302. doi:10.1115/1.3446349.

Radial turbines are used predominantly for turbo-charges where the geometry is frequently compromised to favor low fabrications costs. Theoretical as well as experimental investigations have shown that the efficiency potential of radial turbines is as high as the efficiency potential of high reaction axial turbines. Structural and heat transfer studies on radial turbines show that the highest stresses in “deep scalloped” radial rotors occur at locations where the metal temperature is considerably lower than at rotor inlet. Thus the maximum allowable gas inlet temperature for radial turbines is several hundred degrees higher than for high-reaction axial turbines. This difference tends to increase with increasing expansion ratios, at least up to expansion ratios of 10:1. Since the thermal efficiency of typical gas turbine cycles increases with increasing gas temperatures and increasing expansion ratios, it results that the application of uncooled radial turbines will yield cycle efficiencies which are not obtainable with uncooled axial turbines.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):303-307. doi:10.1115/1.3446350.

Results of an experimental investigation of film cooling and heat transfer following injection through two staggered rows of holes are reported. The two staggered rows are considerably more effective in protecting the wall than a single row. The film cooling effectiveness at locations beyond about 30-hole dia downstream of injection is laterally uniform. The heat transfer coefficient is within a few percent of that without injection at low blowing rates, but it increases rapidly as the blowing rate increases above unity.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):308-316. doi:10.1115/1.3446351.

The initial development of a nonaxisymmetric vectoring exhaust nozzle has been completed for the U. S. Navy by the General Electric Company. This exhaust system, called ADEN (Augmented Deflector Exhaust Nozzle), has been tested at GE’s Peebles, Ohio test facility using a YJ101 engine as the gas producer. This paper reviews the structural and cooling design of the ADEN nonaxisymmetric nozzle. Temperature and pressure data from the test series are compared to design intent for the nozzle operating in normal cruise and deflected (vectored) modes.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):317-325. doi:10.1115/1.3446352.

Applying free streamline theory and singularity method, a theoretical study is developed for the torsional flutter problem in fully stalled cascade. Aerodynamic moment acting on a vibrating blade is calculated for some cascade conditions. Computational results show that critical reduced frequency is much higher in the case of stalled cascade than unstalled cascade and affected by the position of pitching center. Experiments were carried out using a water tunnel with a linear cascade, and the unsteady moment acting on the vibrating blade was measured. Computational and experimental results show fairly good agreement.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):326-332. doi:10.1115/1.3446353.

A detailed investigation of the effect of the shape of an open combustion chamber for diesel engine on the air velocity pattern, and consequently, on the trajectory of the fuel spray is given in this paper. A theoretical model for the calculation of the spray penetration, taking into consideration the heat transfer to the droplet, the variation of the drag force with Reynolds number, and air velocity pattern, is suggested. The effect of some working conditions on the spray shape, trajectory, and penetration is experimentally studied to verify the theoretical model and to correlate the results of using different medium pressures, initial spray velocity, and injection angle on the magnitude of fuel spray diameter and spray volume.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):333-343. doi:10.1115/1.3446354.
Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):347-355. doi:10.1115/1.3446361.

The Large Leak Test Rig (LLTR) and its role in providing information on the consequences of large sodium-water reactions in sodium-heated steam generators is described. Facility startup problems and subsequent operating experiences are discussed. Instrumentation and data acquisition methods are identified and typical data from initial tests using the 30-MWt Modular Steam Generator (hockey-stick steam generator) as a test article are presented. Information also is included on post-test inspection methods, equipment, and results. Facility modifications to permit testing of steam generator geometries, systems, and equipment more nearly prototypic of those for large LMFBR’s are described.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):356-362. doi:10.1115/1.3446362.

Methods for performing finite element stress analysis of perforated plates under pressure and complex thermal loading conditions are described. The concept of the equivalent solid material of anisotropic properties is employed to define the elasticity matrices to be used for axisymmetric analysis of plates containing triangular and square patterns of circular holes. Generalized plane strain effective elastic constants are used for better approximation of the overall plate behavior. New methods and curves for obtaining local ligament stresses from the nominal stresses in the equivalent solid material are given.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):363-368. doi:10.1115/1.3446363.

The new Heat Exchange Institute (HEI) condenser standard [1] provides a method for tubesheet analysis. The historical background of this method is reviewed. The structural design problem of a rectangular tubesheet is described. A condenser tubesheet is seen to be a partially perforated plate on an elastic foundation, with the tubes comprising the foundation. The hydrostatic pull from the waterbox and surface pressure on the tubesheet are the dominant loads. Irregular tube patterns and variation in edge boundary conditions make solution of the plate problem difficult. The HEI proposes a simplified approximation: a narrow strip of tubesheet with its supporting row of tubes, analyzed as a beam on an elastic foundation. A discussion is presented of the assumptions required, allowable stress criteria, and the uncertainties involved. A preloading device is described. Some suggestions for future work are made.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):369-373. doi:10.1115/1.3446364.

Steam venting to atmosphere from piping system pressures as high as 2500 psig, as may occur during safety valve and power relief valve operation or during initial steam piping clean up, is one of the most intense sources of noise emitted by fossil and nuclear power plants. This paper discusses characteristics of sonic and turbulent vent noise. Analytical methods to estimate vent noise intensity and frequency characteristics are presented for use where unsilenced noise measurements are not feasible. Design considerations in the effective use of silencers and acoustic lagging materials are discussed. Power plant noise measurements illustrating the severity of the noise emission and its control are presented.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):374-379. doi:10.1115/1.3446365.

With fuel supplies changing and directives of policy being formulated, the use of coal for the industrial plant is of major concern for many owners. This paper discusses many of the questions which are asked on this subject for retrofitting existing plants and for designs of new coal-fired plants. One particular area for discussion is coal gasification for existing plants with package boilers. Estimated capital and operating costs are reviewed for various size ranges applicable to the industrial power plant.

Commentary by Dr. Valentin Fuster
J. Eng. Power. 1978;100(2):380-388. doi:10.1115/1.3446366.

A computer-oriented method for axisymmetric stress analysis of integral tubesheet exchangers is developed. The tubesheet is modeled as a composite plate consisting of a perforated interior and a solid annular plate bonded at the interface radius. The interaction of the shell and channel with the tubesheet is included in the analysis. To incorporate the effect of gravity loads in vertical units, the shell and tubeside pressures are allowed to be different at the two tubesheet locations. An analytical expression for the differential longitudinal expansion of the tubes over the shell is also devised.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

Commentary by Dr. Valentin Fuster

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