The two-phase flow downstream of a production gas-turbine engine combustor fuel injection system (i.e., "swirl cup") is characterized at atmospheric pressure in the absence of reaction. The swirl cup features a centrally located simplex atomizer, a surrounding liquid filming surface, and counter-swirling air streams. Two-component phase Doppler interferometer is employed to determine the time averaged droplet size and velocity distributions and the time-averaged velocities of the continuous phase (gas-phase in the presence of spray). The time-dependent behavior of both phases is documented with a high-speed video camera. This work represents the first detailed characterization of the two-phase flow field in a production fixture and reveals the complexity of the flow field produced. The interferometric results, for example, reveal an on-axial recirculation zone and show that droplets are entrained as a function of size. Large slip velocities between the gas phase and the droplets are measured in all regions of the flow, indicating the presence of momentum transfer between phases. The magnitude of the slip velocities is correlated with droplet size. High speed photographs (1) reveal the dynamic behavior of the droplet and continuous phase, (2) identify clustering of droplets, and (3) reaffirm a correlation of droplet recirculation with size. © 1992 Combustion Institute.

A production gas turbine combustor swirl cup and a 3x-scale model, both featuring co-axial, counter-swirling air streams are characterized at atmospheric pressure and in the absence of reaction. Spatially-resolved measurements of continuous phase (gas in the presence of spray) and droplet size and velocity are acquired downstream of the production and 3x-scale swirl cups by using two-component phase Doppler interferometry. The effect of scale on the behavior of the continuous phase and droplets is investigated by comparing the continuous phase velocity and droplet size and velocity at geometrically analogous positions. The continuous phase flow field scales well at the exit of the swirl cup. Farther downstream, differences occur which are due to disparity in entrainment. The droplet velocities scale reasonably well, but the sizes show some differences. However, the difference in size is less significant than it is between the two atomizers in the absence of the swirl cup assemblies.

A production gas turbine combustor swirl cup and a3× -scale model (both featuring co-axial, counterswirling air streams) are characterized at atmospheric pressure. Such a study provides an opportunity to assess the effect of scale on the behavior of the continuous phase (gas in the presence of spray) and droplets by comparing the continuous phase velocity, droplet size, and droplet velocity at geometrically analogous positions. Spatially resolved velocity measurements of the continuous phase, droplet size, and droplet velocity were acquired downstream of the production and 3 X -scale swirl cups by using two-component phase-Doppler interferometry in the absence of reaction. While the continuous phase flow fields scale well at the exit of the swirl cup, the similarity deviates at downstream locations due to (1) differences in entrainment, and (2) a flow asymmetry in the case of the production hardware. The droplet velocities scale reasonably well with notable exceptions. More significant differences are noted in droplet size, although the presence of the swirl cup assemblies substantially reduces the differences in size that are otherwise produced by the two atomizers when operated independent of the swirl cup. © 1993 ASME.

The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 ¹/₂ years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.