To improve the efficiency of direct laser deposition (DLD) metal powders, a concentrated powder-stream distribution is required, which can be affected by shape powder-delivery nozzle. In this study, simplified, powder particle–wall collision-based 3D numerical model flow in nozzle was used to simulate influences nozzle-exit on concentration stream distribution, characterized its diameter. The p...

Direct numerical simulation is used to study the effect of crossflow on the dynamics, entrainment and mixing characteristics of vortex rings issuing from a circular nozzle. Three distinct regimes exist, depending on the velocity ratio (ratio of the average nozzle exit velocity to free-stream crossflow velocity) and stroke ratio (ratio of stroke length to nozzle exit diameter). Coherent vortex r...

Purpose. To calculate the temperature and velocity of nickel aluminum oxide particles in supersonic flow low-pressure cold gas-dynamic spraying nozzle. investigate effect gas parameters at nozzle inlet, particular pressure, on outlet.
 Research methods. The calculation temperature-velocity characteristics powder is performed after determining channel using well known dependencies. initial ...

R134a sprays have been widely used as a method to protect the epidermis during laser therapies of hyper-vascular lesions, such as port wine stains, due to their high heat flux and precise control of cooling duration. Recent studies have shown that the use of vacuum cups during laser treatment can physically dilate the vasculature of interest and improve therapeutic outcome. However, the effects...

Bioprinting of living cells can cause major shape deformations, which may severely affect cell survival and functionality. While the shear stresses occurring during flow through printer nozzle have been quantified to some extent, extensional as leave into free printing strand mostly ignored. Here we use lattice Boltzmann simulations together with a finite-element based model study deformation i...

We present a new photo-fragment imaging spectrometer, which employs a movable repeller in a single field imaging geometry. This innovation offers two principal advantages. First, the optimal fields for velocity mapping can easily be achieved even using a large molecular beam diameter (5 mm); the velocity resolution (better than 1%) is sufficient to easily resolve photo-electron recoil in (2 + 1...

A method is presented whereby the translational velocity of a vortex ring can be approximated from the total circulation, impulse, and kinetic energy of the vortex system. Assuming a uniform vorticity density, these bulk quantities define a unique stable vortex ring configuration, and the translational velocity can be inferred from this configuration and the system scaling. Here, the accuracy o...

We present a novel pneumatic actuation system for generation of liquid metal droplets according to the so-called StarJet method. In contrast to our previous work, the performance of the device has been significantly improved: the maximum droplet generation frequency in continuous mode has been increased to fmax = 11 kHz (formerly fmax = 4 kHz). In addition, the droplet diameter has been reduced...

The performance of a single spray for electronic power devices using deionized (DI) water and pure silver (Ag) particles as well as multi-walled carbon nanotube (MCNT) particles, respectively, is studied herein. The tests are performed with a flat horizontal heated surface using a nozzle diameter of 0.5 mm with a definite nozzle-to-target surface distance of 25 mm. The effects of nanoparticle v...