Experimental investigations on rotation–vibration energy transfer in H2-N2 collisions

We investigated the rotational-vibrational impact energy transfer processes in a H2–N2 gas mixture system. The stimulated Raman pumping technique was used to excite H2 molecules to the (1,7) high rotational states. The population of the H2(1,7) level was verified by the coherent anti-Stokes Raman (CARS) spectra, the total pressure of the mixture was maintained at 500 Torr, and nitrogen with different molar ratios was filled in the sample cell. The collisional deactivation rate coefficients of the excited state H2(1,7) with H2 and N2 were obtained by fitting the experimental data with the Stern–Volmer equation. The multi-quantum near-resonant rotational relaxation process of H2(1, 7) colliding with N2 was confirmed by the time-resolved CARS profile measurements of H2(v=1, J=7, 5, 3) after the excitation of H2(1, 7).

Effect of Superimposed Vibrations on Droplet Oscillation Modes in Prilling Process

This article was aimed to solve an urgent problem of ensuring quality for prilling processes in vibrational prilling equipment. During the research, the need for the application of vibrational prilling to create a controlled impact on the process of jet decay on droplets with the proper characteristics was substantiated. Based on the experimental and theoretical studies of the process of decay of a liquid jet into drops, axisymmetric droplet oscillation modes for the different frequencies were observed. Frequency ranges of transition between modes of decay of a jet into drops were obtained. As a result, the mathematical model of the droplet deformation was refined. The experimental research data substantiated this model, and its implementation allowed determining the analytical dependencies for the components of the droplet deformation velocity. The proposed model explains the existence of different droplet oscillation modes depending on the frequency characteristics of the superimposed vibrational impact. Based on an analytical study of the droplet deformation velocity components, the limit values of the characteristics defining the transition between the different droplet oscillation modes were discovered. Analytical dependencies were also obtained to determine the diameter of the satellites and their total number.

Thermal vibrational convection of a pseudoplastic fluid in a rectangular cavity

Thermal vibrational convection of a pseudoplastic fluid in a closed rectangular cavity, which is in zero gravity and performing longitudinal high-frequency linearly polarized vibrations, is studied. The temperature gradient is perpendicular to the direction of vibration. The system of equations of thermovibrational convection of a Williamson pseudoplastic fluid is given. The problem was solved by the finite difference method. The effect of vibrations on the structure and intensity of flows is investigated. The magnitude of the vibrational effect on the liquid was determined by the vibrational Grashof number. The dependences of the maximum of the stream function and the Nusselt number, which determines the heat flux through the boundary of the cavity, on the vibrational Grashof number are obtained. The threshold values of the vibrational Grashof number and the Nusselt number corresponding to a change in the flow regime are determined. At small values of the Grashof vibration number in the cavity, a slow four-vortex symmetric flow is observed. With an increase in the vibrational impact, an intense three-vortex motion arises in the cavity, which transforms into five vortex-like motion. For the five vortex flows, there exists the region of Grashof vibration numbers, where this flow is oscillatory in nature. With increasing degree of non-Newtonian fluid, initially periodic oscillations become chaotic.

An assessment of transmission efficiency on a hard disk’s vibration

At present, there is a trend to design a hard disk with a larger capacity, a faster revolution speed, and a precise mechanism. Therefore, the influence of data transmission with respect to vibration is obvious. To reduce interference of the vibrational impact on the data transmission efficiency, vibrational abatement on the hard disk using the damping material becomes crucial. Because of the complicated relationship for the damping coefficient and spring constant to the hardness (D1, D2, and D3) of the damping material installed under the hard disk, it is difficult to theoretically assess an optimal hardness combination of the damping material. Therefore, an alternative way by using an experimental study in conjunction with Taguchi method, an Artificial Neural Network (ANN), and a GA Method is proposed. In this paper, a hard disk is placed on a vibration tester that is an analogue to a dynamic vibrational circumstance induced by a vibrational base. The data transfer rate of the hard disk will be detected by using IOmeter software under various base-excitation accelerations, tilted angles of the hard disk, and targeted frequencies. To reduce the vibrational impact on the data transmission efficiency, an assessment of an optimal three-layer damping material installed under the hard disk using the Taguchi method, the Artificial Neural Network (ANN), and the GA Method is proposed. Before the optimization of the damping material is performed, the required experimental sets (the hardness for three layers of damping material) of the data transmission testing with respect to various design parameters will be determined by using the Taguchi method. The ANN, a simplified objective function (OBJ), will be established by inputting the hardness of three layers of damping material and their related data transmission efficiency at three targeted frequencies. Thereafter, the optimal hardness for three layers of the damping material will be obtained using a genetic algorithm (GA). Consequently, the optimal hardness of the three-layer damping material with respect to various tilted angles and target frequencies will be assessed.

Hydraulic Power of Vibration Test Stand with Vibration Generator Based on Switching Device

The article reviews the problems of vibration stand development for vibration testing of technological devices with hydraulic power equipped with a switching device to create modes for tested products pre-scanning and to carry out resonance frequency tests. The proposed development will enhance the effect of such tests due to spectrally rich vibrational impact on tested products.