Use of surface heat transfer measurements as a flow separation diagnostic in a two dimensional reflected oblique shock/turbulent boundary layer interaction

The feasibility of using streamwise surface heat transfer measurements to detect the presence of flow separation in a two-dimensional reflected oblique shock/turbulent boundary layer interaction is reported. Surface heat transfer and static pressure data are presented for attached and separated flows for a free stream nominal Mach number range of 2.5 to 3.5 and shock generator angles of 2 to 8 degrees. The static pressure data do show the characteristic triple inflection point distribution for the strongly separated flow cases. The corresponding surface heat transfer data show unique trends that correlate well with the static pressure determination of the extent of the separated flow region. For the incipient or weakly separated flow cases, the static pressure data do not exhibit the characteristic triple inflection point distribution. However, the same trends in the heat transfer data that are seen for the strongly separated flow cases are evident for the weakly separated flows. Hence, the heat transfer data can be used to determine the extent of weakly separated flows when the surface static pressure distributions often can not

Economics of payment cards: a status report

This article surveys the recent theoretical literature on payment cards (focusing on debit and credit cards) and studies this research's possible implications for the current public policy debate over payment card networks and the pricing of their services for both consumers and merchants.Payment systems ; Credit cards

Heat transfer, velocity-temperature correlation, and turbulent shear stress from Navier-Stokes computations of shock wave/turbulent boundary layer interaction flows

The properties of 2-D shock wave/turbulent boundary layer interaction flows were calculated by using a compressible turbulent Navier-Stokes numerical computational code. Interaction flows caused by oblique shock wave impingement on the turbulent boundary layer flow were considered. The oblique shock waves were induced with shock generators at angles of attack less than 10 degs in supersonic flows. The surface temperatures were kept at near-adiabatic (ratio of wall static temperature to free stream total temperature) and cold wall (ratio of wall static temperature to free stream total temperature) conditions. The computational results were studied for the surface heat transfer, velocity temperature correlation, and turbulent shear stress in the interaction flow fields. Comparisons of the computational results with existing measurements indicated that (1) the surface heat transfer rates and surface pressures could be correlated with Holden's relationship, (2) the mean flow streamwise velocity components and static temperatures could be correlated with Crocco's relationship if flow separation did not occur, and (3) the Baldwin-Lomax turbulence model should be modified for turbulent shear stress computations in the interaction flows

Workmen\u27s Compensation Legislative Trends Throughout the Country

Any attempt to comprehensively analyze the voluminous and detailed Workmen\u27s Compensation and Industrial Employee legislation throughout the United States awakens one to the vast scope of ourmindustrial society. The magnitude of progress in this field dominates all other considerations of this survey, designed to show what aspects of these laws are in the throes of legislative revision, with emphasis on advances in vocational rehabilitation, coverage of public employees, and expansion of occupational disease classifications. This survey encompasses not only legislative revisions, repeals and amendments proposed or pending before State lawmakers, but attempts a preview of future activity

Workmen\u27s Compensation Legislative Trends Throughout the Country

Any attempt to comprehensively analyze the voluminous and detailed Workmen\u27s Compensation and Industrial Employee legislation throughout the United States awakens one to the vast scope of ourmindustrial society. The magnitude of progress in this field dominates all other considerations of this survey, designed to show what aspects of these laws are in the throes of legislative revision, with emphasis on advances in vocational rehabilitation, coverage of public employees, and expansion of occupational disease classifications. This survey encompasses not only legislative revisions, repeals and amendments proposed or pending before State lawmakers, but attempts a preview of future activity

A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high speed flow fields

PROPULSION APPARATUS FOR SPACE VEHICLES AND CORRESPONDING METHOD

Propulsion apparatus (10) for space vehicles, comprising a solid state oxygen-rich source layer (11), means (12) for extracting oxygen from said solid state oxygen-rich source layer (11), means (16, 14, 17) for accelerating correspondingly extracted oxygen ions into vacuum. According to the invention, it comprises a stack including said solid state oxygen-rich source layer (11), an active layer (16) being deposited above said solid state oxygen-rich source layer (11), in contact with said solid state oxygen-rich source layer, said active layer (16) being formed with a material different from said solid state oxygen-rich source layer (11), said material being an oxide presenting impedance hysteresis behavior, i.e. a memristor, wherein in a low resistance state oxygen ions (22) are expelled through the active layer (16) and wherein in a high resistance state the active layer (16) ceases expelling oxygen ions (22)

Dynamic Pressure Probes Developed for Supersonic Flow-Field Measurements

A series of dynamic flow-field pressure probes were developed for use in large-scale supersonic wind tunnels at the NASA Glenn Research Center. These flow-field probes include pitot and static pressure probes that can capture fast-acting flow-field pressure transients occurring on a millisecond timescale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The flow-field pressure probe contains four major components: 1) Static pressure aerodynamic tip; 2) Pressure-sensing cartridge assembly; 3) Pitot pressure aerodynamic tip; 4) Mounting stem. This modular design allows for a variety of probe tips to be used for a specific application. Here, the focus is on flow-field pressure measurements in supersonic flows, so we developed a cone-cylinder static pressure tip and a pitot pressure tip. Alternatively, probe tips optimized for subsonic and transonic flows could be used with this design. The pressure-sensing cartridge assembly allows the simultaneous measurement of steady-state and transient pressure which allows continuous calibration of the dynamic pressure transducer