Formation of singularities on the surface of a liquid metal in a strong electric field

The nonlinear dynamics of the free surface of an ideal conducting liquid in a strong external electric field is studied. It is establish that the equations of motion for such a liquid can be solved in the approximation in which the surface deviates from a plane by small angles. This makes it possible to show that on an initially smooth surface for almost any initial conditions points with an infinite curvature corresponding to branch points of the root type can form in a finite time.Comment: 14 page

Creating a Database of Helicopter Main Rotor Acoustics for Validation of CFD Methods

The work presents recent experiments at the Kazan National Technical University (KNRTU-KAI), related to helicopter acoustics. The objective is to provide a database of near-field experimental data suitable for CFD validation. The obtained set of data corresponds to a Mach-scaled rotor of known planform. An advantage of the current dataset is that direct near-field acoustic data is made available and this allows easy and direct comparisons with CFD predictions, without the need to use far-field aeroacoustic methods

Helicopter Fuselage Drag ─ Combined Computational Fluid Dynamics and Experimental Studies

In this paper, wind tunnel experiments are combined with Computational Fluid Dynamics (CFD) aiming to analyze the aerodynamics of realistic fuselage con¦gurations. A development model of the ANSAT aircraft and an early model of the AKTAI light helicopter were employed. Both models were tested at the subsonic wind tunnel of KNRTU-KAI for a range of Reynolds numbers and pitch and yaw angles. The force balance measurements were complemented by particle image velocimetry (PIV) investigations for the cases where the experimental force measurements showed substantial unsteadiness. The CFD results were found to be in fair agreement with the test data and revealed some §ow separation at the rear of the fuselages. Once con¦dence on the CFD method was established, further modi¦cations were introduced to the ANSAT-like fuselage model to demonstrate drag reduction via small shape changes

CAA Modeling of Helicopter Main Rotor in Hover

In this work rotor aeroacoustics in hover is considered. Farfield observers are used and the nearfield flow parameters are obtained using the in house HMB and commercial Fluent CFD codes (identical hexa-grids are used for both solvers). Farfield noise at a remote observer position is calculated at post processing stage using FW–H solver implemented in Fluent and HMB. The main rotor of the UH-1H helicopter is considered as a test case for comparison to experimental data. The sound pressure level is estimated for different rotor blade collectives and observation angles

Plasma-assisted deposition of dielectric conformal coating using hexamethyldisiloxane as precursor

Plasma polymerization is a rapidly growing field of plasma technology. Using this method, it is possible to solve applied problems, for example, the deposition of conformal dielectric coatings to protect electrical circuit boards operating in outer space. In this paper, we study the vapor deposition of hexamethyldisiloxane using low-pressure plasma. The morphology, dielectric strength under plasma, and chemical composition of the deposited coating are studied. It was established that the coating has a lamellar structure, which, together with the data of IR spectroscopy, indirectly prove the formation of a polymer coating. The dielectric strength of the coating under plasma was 650 V