ES2010-90418 ON THE DEVELOPMENT OF A LOW COST PYRHELIOMETER

ABSTRACT A low cost pyrheliometer, based on a thermoelectric sensor, was developed at the Energy and Sustainability Center at the Florida State University. In addition, an inexpensive doubleaxis tracking device, capable of autonomous operation, enables the pyrheliometer to operate as a stand-alone system. Widely available off-the-shelf components were used and compromises in accuracy and time responsiveness were made in order to keep the cost low. The obtained data was compared with an Eppley Normal Incidence Pyrheliometer (NIP) using model ST-1 solar tracker. Steady state values of irradiance were measured with an accuracy better than ±2%. Transient measurements are time delayed by a thermal lag of about two minutes, which leads to a high error for instantaneous measured values. However, the integrated irradiance over the course of any given day yields irradiation values with accuracy better than ±2%, even on days when the sun and clouds quickly alternate. Based on a manufacturing cost analysis, the prototype pyrheliometer is anticipated to cost less than $500 if mass-produced. NOMENCLATUR

Solar Thermal Power [video]

NPS Defense Energy SeminarDr. Anjaneyulu Krothapalli, Don Fuqua Eminent Scholar Chair & Professor Emeritus of Mechanical Engineering at Florida State University (FSU)Harvesting solar radiation and converting into useful heat has been subject of intense research because of its use in a wide variety of engineering applications. In early years of solar energy implementation, the direct conversion of solar radiation to electricity using Photovoltaics took the center stage and except for the space applications, it was not considered for common use because of its cost. However, with recent advances in Photovoltaics manufacturing, the cost of solar electricity generation has plummeted to about $0.07 per Kwh making it the most affordable for everyday applications. Photovoltaic power plants and wind farms are being inherently intermittent, solar thermal heat storage and power generation will complement the existing renewable energy grid. Since storing electricity is not a particularly efficient process and heat storage being far easier and efficient method, solar thermal becomes very attractive to large-scale energy production. Many manufacturing industry uses saturated steam at relatively low pressures. A novel flat solar panel, Multiple Parabolic Reflector Flat Panel Solar Collector, is described to heat a working fluid to a maximum temperature of 150oC. The parabolic reflectors in the panel remain stationary, while the receiver moves to track the sun, thereby allowing for maximum energy collection with minimum amount of sun tracking

NCAD2008-73071 ON THE FAR-FIELD PROPAGATION OF HIGH-SPEED JET NOISE

ABSTRACT This paper deals with the effects of atmospheric absorption on the propagation of high-speed jet noise. The common practice for determining the far-field jet noise spectra at a distance far from the jet exit (>100D, where D is the nozzle exit diameter) involves extrapolating data that is typically obtained between 35D and 100D from the nozzle exit. The data is extrapolated along a radial line from the nozzle exit by accounting for the effects of spherical spreading and atmospheric absorption. A previous paper discussed far-field measurements that were obtained for a twin engine aircraft at three locations along a radial line in the peak noise radiation direction. The authors were unable to extrapolate the spectra from the nearest location to either of the further locations and the observed differences were attributed to nonlinear effects in the jet noise signal. It is the purpose of this paper to show that the common extrapolation practice is valid for high speed jets, except in the peak radiation direction and its surrounding angles. Mach wave radiation is present at these locations and the common practice will yield unsatisfactory results, similar to those observed in the previous paper. The data used in this paper is taken from experiments carried out at 1 5 th-scale and full scale and the experimental conditions of these high-speed jets are quite similar to those of the previous paper

International Symposium on Recent Advances in Aerodynamics and Acoustics

The Joint Institute for Aeronautics and Acoustics at Stanford University was established in October 1973 to provide an academic environment for long-term cooperative research between Stanford and NASA Ames Research Center. Since its establishment, the Institute has conducted theoretical and experimental work in the areas of aerodynamics, acoustics, fluid mechanics, flight dynamics, guidance and control, and human factors. This research has involved Stanford faculty, research associates, graduate students, and many distinguished visitors in collaborative efforts with the research staff of NASA Ames Research Center. The occasion of the Institute's tenth anniversary was used to reflect back on where that research has brought us, and to consider where our endeavors should be directed next. Thus, an International Symposium was held to review recent advances in the fields relevant to the activities of the Institute and to discuss the areas of research to be undertaken in the future. This anniversary was also chosen as an opportunity to honor one of the Institute's founders and its director, Professor Krishnamurty Karamcheti. It has been his crea­ tive inspiration that has provided the ideal research environment at the Joint Institute

Compressible dynamic stall control using high momentum microjets

The article of record as published may be found at http://dx.doi.org/10.1007/s00348-014-1813-6Control of the dynamic stall process of a NACA 0015 airfoil undergoing periodic pitching motion is investigated experimentally at the NASA Ames compressible dynamic stall facility. Multiple microjet nozzles distributed uniformly in the first 12 % chord from the airfoil’s leading edge are used for the dynamic stall control. Point diffraction interferometry technique is used to characterize the control effectiveness, both qualitatively and quantitatively. The microjet control has been found to be very effective in suppressing both the emergence of the dynamic stall vortex and the associated massive flow separation at the entire operating range of angles of attack. At the high Mach number (M = 0.4), the use of microjets appears to eliminate the shock structures that are responsible for triggering the shock-induced separation, establishing the fact that the use of microjets is effective in controlling dynamic stall with a strong compressibility effect. In general, microjet control has an overall positive effect in terms of maintaining leading edge suction pressure and preventing flow separation.NASA Ame