The temporal instability and primary breakup length of a non-Newtonian viscoelastic liquid jet moving in an inviscid gaseous environment were carried out by solving a set of linearized Navier-Stokes equations and employing the linear viscoelastic model, respectively. The dimensionless dispersion equation that governs the instability was derived and solved by a numerical method. The effects of fluid properties on the instability and primary breakup length of viscoelastic liquid jets were carried out. It could be seen that by increasing the growth rate, the instability range and the primary breakup length of the viscoelastic liquid jets could result in an increase in the liquid Weber number and the ratio of gas to liquid density. Moreover, the significant findings are that an increase in the time constant ratio, and also the Ohnesorge number reduced both of the growth rates of disturbances and primary breakup length. Though, increasing the elasticity number resulted in a higher growth rate of disturbances and enhanced the breakup mechanism.

The study presented in this paper concerns the ventilation system inside tunnels. The ventilation system is responsible for the removal of exhaust gases produced by vehicles and for providing a clear view throughout the tunnels in routine operations and in the event of fire. The ventilation system has several stages, which are equipped with one or more fans and can be activated together or separately. The objective of this study is to find a better correlation between the air velocity and number of ventilation stages inside a tunnel. A small experimental model representing a miniature model of a tunnel was built for the study. In addition, the problem was modelled using computational fluid dynamics (CFD) in ANSYS® Fluent 18.0 for comparison and verification. The results from experiments with the miniature model and simulations from the CFD study were found to be in good agreement and in relation to a real-case scenario. The results also indicated that an increase in the active number of ventilation stages does not result in a linear increase in the air velocity inside the tunnel.

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The shock wave of near-field underwater explosion is investigated experimentally and numerically. Three TNT charge of different shapes are detonated in the water tank. The framing &scanning ultra-high speed photography system is applied to obtain the initial movement and trajectories of shock wave and detonation gas. Use the Arbitrary Lagrangian–Eulerian (ALE) method of LS-DYNA software to simulate the processes of near-field underwater explosion. Comparisons with the experimental tests are conducted to verify the results of numerical solutions. The movement characteristics of explosion loads are matched well. On the basic of experiments and simulations, the engineering formula of pressure for near-field shock wave is built.

Experiments on penetrating into concrete and pebble layered targets were performed by shaped charge with different cone angles, liner wall thicknesses, length to diameter ratios and charge diameters at different standoffs. Based on the experimental data, the influence of shaped charge’s structural parameters on crater diameter, hole diameter, crater depth and penetration depth was analyzed in detail. Meanwhile, formation and penetration processes of all shaped charges were simulated by AUTODYN software for investigating the more intrinsic mechanisms, in which the numerical models are the same as those set up in the experiments. The results obtained in this paper indicate that there are obvious differences between jetting projectile charge (JPC) and explosively formed projectile (EFP) in penetrating into multi-layer targets. For the same charge diameter, the values of hole diameter formed by EFP were much larger than JPC. However, for the same standoff, the penetration depth caused by JCP were larger than EFP. The interfacial effect exists in the penetration progress of JPC.

In recent years most of the oil reserves discovered has been related to heavy oil reservoirs whose reserves are abundant but still show operational difficulties. This fact provoked great interest of the petroleum companies in developing new technologies for increasing the heavy oil production. Produced water generation, effluent recovered from the production wells together with oil and natural gas, is among the greatest potential factors for environmental degradation. Thus, a new scenario of the oil industry appears requiring improvement in treatment units for produced water. Among the technological improvements in the facilities, the use of hydrocyclones has been applied in the treatment of the oily water. In this sense, this study aims to investigate numerically the separation process of heavy oil from a water stream via hydrocyclone, using the computational fluid dynamics technique. In the mathematical modeling was considered a two-phase, three-dimensional, stationary, isothermal and turbulent flow. Results of streamlines, pressure and volume fraction fields of the involved phases (oil and water) into the hydrocyclone, and mechanical efficiency and pumping power of the fluids are shown and analyzed. In conclusion, it seems that with increasing fluid input velocity in the device there is an increase in pressure drop, indicating a greater pumping energy consumption of the mixture, and greatly influences the separation process efficiency.

Wind power is a sustainable source of energy. However, there are certain challenges to be overcome. One of the operational challenges is the phenomenon of ice shedding. Icing happens on wind turbine blades in cold regions. When ice grows to a certain size, it separates from the wind turbine blades resulting in the phenomenon of ice shedding. This phenomenon is of significantly dangerous for equipment and personnel in the region. Ice shedding may happen either because of vibrations or bending in blades. However, it was noticed by operators at Nygardsfjell wind park, Narvik, Norway that ice shedding is more probable to happen when blades are stopped and turned back on. This observation reveals the fact that bending of blades (from loaded to unloaded positions) allows the ice to separate and hence result in ice shedding. This can be linked to the phenomenon of icing, mechanical and adhesive properties of ice. This paper reviews above in detail.

As a prerequisite for studying and ultimately improving the powder coating process, particle motion and deposition effects within flow- and electro-static fields need to be thoroughly understood and thus characterized. In this context, a range of dimensionless groups is proposed and new means of characterization are presented. Considering the impact of electro-static, fluid-dynamic and gravity forces on coating particle motion, a triangle chart notation to characterize the state of varying particle size classes, is introduced. Furthermore a derivation of the dimensionless particle momentum equation is shown to lead to a dimensionless chart, representing all possible process states of coating. In combination with a Eulerian-LaGrangian, numerical model, the new means of characterization have led to a far better, over all perspective of occurring phenomena and their causes. Some examples are demonstrated here.

Combustor design is the most unreliable and challenging portion in the design process of a gas turbine. To ensure the proper performance, many experimental tests must be performed on a combustor in the industry. The above mentioned design phase is costly and time consuming. This paper focused on an automated and augmented conceptual design methodology for conventional combustors. The design tool developed for this study employs empirical and semi-empirical models which include two main parts of the combustor, the reference diameter and area as well as the component design. The necessity of this work arose from an urgent need for comprehensive and fast generation data in the conceptual design phase of a combustion chamber. This automated and comprehensive tool, equipped with the capacity to provide many details, has a considerable impact on the reduction of further experimental effort. Also, the said tool is equipped with a geometrical model generation section that has application in the future design phases, e.g., detail design.

The use of several developmental approaches is the researchers’ major preoccupation with the DARRIEUS wind turbine. This paper presents the first approach and results of a wide computational investigation on the aerodynamics of a vertical axis DARRIEUS wind turbine based on the MAGNUS effect. Consequently, wind tunnel tests were carried out to ascertain overall performance of the turbine and two-dimensional unsteady computational fluid dynamics (CFD) models were generated to help understand the aerodynamics of this new performance. Accordingly, a moving mesh technique was used where the geometry of the turbine blade was cylinders. The turbine model was created in Gambit modeling software and then read into fluent software for fluid flow analysis. Flow field characteristics are investigated for several values of tip speed ratio (TSR), in this case we generated a new rotational speed ratio between the turbine and cylinder (δ = ωC/ωT). This new concept based on the MAGNUS approach provides the best configuration for better power coefficient values. The positive results of Cp obtained in this study are used to generate energy; on the other hand, the negative values of Cp could be used in order to supply the engines with energy.