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Aircraft carriers are essential for modern naval operations. Takeoff maneuver is critical because of the short runway distance. The ski-jump ramp is a system which increases the angle of attack of the aircraft, so an extra lift is obtained. Regarding the flow configuration over the ski-jump ramp at ahead wind conditions, the complex aerodynamic environment generated by the ramp configuration influences aircraft operations. This flow field is mainly characterized by a low velocity recirculation bubble that reduces aircraft performances. The purpose of this paper is to find a solution to reduce these adverse effects, by means of flow control devices, which opens a wide field of research.

This paper presents wind tunnel tests performed to study the flow configuration in the vicinity of the ski-jump ramp and the flow control devices effects. A 1:100 scaled ship model was built to develop experimental tests by using flow control devices fabricated by means of additive manufacturing. Particle image velocimetry technique was used to measure the velocity flow field and the turbulence intensity maps.

Interesting results were obtained when the angle between the intersection of the ski-jump ramp and the columnar vortex generator (CVG) is modified. The results showed a high reduction of the recirculation bubble generated over the flight deck.

CVG has presented encouraging results as a passive flow control device. A study of the variation of CVG geometrical parameters has been developed.

The purpose of this paper is to study the effects of uniform injection and suction through a perforated pentagonal cylinder on the flow field and heat transfer.

The finite-volume method has been used to solve the ensemble-averaged Navier-Stokes equations for incompressible flow at moderate Reynolds number (Re = 22,000) with the k-ɛ turbulence model equations.

A computational fluid dynamics analysis of turbulent flow past a non-regular pentagonal cylinder with three different aspect ratios aspect ratios has been carried out to investigate the effects of uniform injection/suction through the front and all surfaces of the cylinder. It is found that flow field parameters such as drag coefficient, pressure coefficient and Nusselt number are affected considerably in some cases depend on injection/suction rate (Γ) and perforated wall position.

To optimize the efficiency of the injection and suction through a perforated surface, both wide-ranging and intensive further studies are required. Using various perforation ratios and injection/suction intensities are some possibilities.

Control of the vortex shedding and wake region behind bluff bodies is of vital interest in fluid dynamics. Therefore, applying uniform injection and suction from a perforated bluff body into the main flow can be used as a drag reduction mechanism, thermal protection and heat transfer enhancement.

This study provides unique insights into the active flow control method around pentagonal cylinders that can be useful for researchers in the field of fluid dynamics and aeronautics.

The purpose of this paper is to understand the natural wind field characteristics of the tunnel entrance section and analyzing the aerodynamic performance of high-speed railway trains (HSRTs) under natural winds.

Three typical tunnel entrance section sites, namely, tunnel–bridge in a dry canyon (TBDC), tunnel–bridge in a river canyon (TBRC) and tunnel–flat ground (TF), are selected to conduct a continuous wind field measurement. Based on the measured wind characteristics, the natural winds of the TBDC and TF sites are reconstituted and imported into the two corresponding full-scale computational fluid dynamics models. The aerodynamic loads of the HSRT running on TBDC and TF with reconstituted winds are simply analyzed.

The von Kármán spectrum can be used to describe the wind field at the tunnel entrance section. In the reconstituted natural wind condition, a time-varying feature of wind speed distribution and leeward side vortex around the HSRT caused by the wind speed fluctuation is found. The fluctuating amplitude of aerodynamic loads at the TBDC infrastructure is up to 97.9% larger than that at the TF infrastructure.

The natural wind characteristics at tunnel entrance sections on the high-speed railway are first measured and analyzed. A numerical reconstitution scheme considering the temporal and spatial variation of natural wind speed is proposed and verified based on field measurement results. The aerodynamic performance of an HSRT under reconstituted natural winds is first investigated.

For Francis turbine, the vortex flow in the draft tube plays an important role in the safe and efficient operating of hydraulic turbine. The swirling flow produced at the blade trailing edge at off-design conditions has been proved to be the fundamental reason of the vortex flow. Exploring the swirling flow variations in the non-cavitation flow and cavitation flow field is an effective way to explain the mechanism of the complex unsteady flow in the draft tube.

The swirling flow in different cavitation evolution stages of varying flow rates was studied. The swirl number, which denotes the strength of the swirling flow, was chosen to systematically analyze the swirling flow changes with the cavitation evolutions. The Zwart–Gerber–Blemari cavitation model and SST turbulence model were used to simulate the two-phase cavitating flow. The finite volume method was used to discrete the equations in the unsteady flow field simulation. The Frozen Rotor Stator scheme was used to transfer the data between the rotor-stator interfaces. The inlet total pressure was set to inlet boundary condition and static pressure was set to outlet boundary condition.

The results prove that the mutual influences exist between the swirling flow and cavitation. The swirling flow was not only affected by the load but also significantly changed with the cavitation development, because the circumferential velocity decrease and axial velocity increase presented with the cavitation evolution. At the high load conditions, the system stability may improve with the decreasing swirling flow strength.

Further experimental and simulation studies still need to verify and estimate the reasonability of the swirling flow seen as the cavitation inception signal.

One interesting finding is that the swirl number began to change as the inception cavitation appeared. This is meaningful for the cavitation controlling in the Francis turbine.

This study aims to review the recent advancements in high entropy alloys (HEAs) called high entropy materials, including high entropy superalloys which are current potential alternatives to nickel superalloys for gas turbine applications. Understandings of the laser surface modification techniques of the HEA are discussed whilst future recommendations and remedies to manufacturing challenges via laser are outlined.

Materials used for high-pressure gas turbine engine applications must be able to withstand severe environmentally induced degradation, mechanical, thermal loads and general extreme conditions caused by hot corrosive gases, high-temperature oxidation and stress. Over the years, Nickel-based superalloys with elevated temperature rupture and creep resistance, excellent lifetime expectancy and solution strengthening L12 and γ´ precipitate used for turbine engine applications. However, the superalloy’s density, low creep strength, poor thermal conductivity, difficulty in machining and low fatigue resistance demands the innovation of new advanced materials.

HEAs is one of the most frequently investigated advanced materials, attributed to their configurational complexity and properties reported to exceed conventional materials. Thus, owing to their characteristic feature of the high entropy effect, several other materials have emerged to become potential solutions for several functional and structural applications in the aerospace industry. In a previous study, research contributions show that defects are associated with conventional manufacturing processes of HEAs; therefore, this study investigates new advances in the laser-based manufacturing and surface modification techniques of HEA.

The AlxCoCrCuFeNi HEA system, particularly the Al0.5CoCrCuFeNi HEA has been extensively studied, attributed to its mechanical and physical properties exceeding that of pure metals for aerospace turbine engine applications and the advances in the fabrication and surface modification processes of the alloy was outlined to show the latest developments focusing only on laser-based manufacturing processing due to its many advantages.

It is evident that high entropy materials are a potential innovative alternative to conventional superalloys for turbine engine applications via laser additive manufacturing.

While working with clients in the last years of his life, Gordon Pask produced an axiomatic scheme for his Interactions of Actors Theory which is a development of his well known Conversation Theory. These axioms are interpretable as a general theory of self‐organisation and are discussed as characteristic of field concurrence and as part of the second‐order cybernetics canon. An application to population density is reported supported by both kinematic and kinetic simulation. Implications for cardiovascular anti‐coagulation therapy and planetary evolution are discussed.