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One of the major challenges in the design of thermal equipment is to minimize the entropy production and enhance the thermal dissipation rate for improving energy efficiency of the devices. In several industrial applications, the structure of thermal device is cylindrical shape. In this regard, this paper aims to explore the impact of isothermal cylindrical solid block on nanofluid (Ag – H₂O) convective flow and entropy generation in a cylindrical annular chamber subjected to different thermal conditions. Furthermore, the present study also addresses the structural impact of cylindrical solid block placed at the center of annular domain.

The alternating direction implicit and successive over relaxation techniques are used in the current investigation to solve the coupled partial differential equations. Furthermore, estimation of average Nusselt number and total entropy generation involves integration and is achieved by Simpson and Trapezoidal’s rules, respectively. Mesh independence checks have been carried out to ensure the accuracy of numerical results.

Computations have been performed to analyze the simultaneous multiple influences, such as different thermal conditions, size and aspect ratio of the hot obstacle, Rayleigh number and nanoparticle shape on buoyancy-driven nanoliquid movement, heat dissipation, irreversibility distribution, cup-mixing temperature and performance evaluation criteria in an annular chamber. The computational results reveal that the nanoparticle shape and obstacle size produce conducive situation for increasing system’s thermal efficiency. Furthermore, utilization of nonspherical shaped nanoparticles enhances the heat transfer rate with minimum entropy generation in the enclosure. Also, greater performance evaluation criteria has been noticed for larger obstacle for both uniform and nonuniform heating.

The current numerical investigation can be extended to further explore the thermal performance with different positions of solid obstacle, inclination angles, by applying Lorentz force, internal heat generation and so on numerically or experimentally.

A pioneering numerical investigation on the structural influence of hot solid block on the convective nanofluid flow, energy transport and entropy production in an annular space has been analyzed. The results in the present study are novel, related to various modern industrial applications. These results could be used as a firsthand information for the design engineers to obtain highly efficient thermal systems.

THIS year's Paris Salon was conspicuously successful, and notably justified the adherence to the international biennial show formula. The permanent building was extended with two large wings of match‐boarding, and there were nearly 200 stands, many representing groups. An increased British participation reflected the opinion that this show is becoming the most important of its kind anywhere.

In a metal rotor blade for rotary wing aircraft, a spanwise load carrying spar, a blade retention fitting by which the blade is adapted to be connected to a rotor hub, said fitting having upper and lower plate‐like members between which the root of said spar is receivable, fastening means extended through the overlapping portions of said spar and fitting, reinforcing plates between said members and said spar having perforate inboard portions through which said fastening means extend and imperforate portions out‐board of said fitting which overlie the upper and lower surfaces of said spar, and adhesive means between the imperforate portions of said plates and the surfaces of said spar for providing load carrying areas free from stress concentrations.

DOWTY Equipment Limited began the study of fuel systems for gas turbines in 1944, following the adoption by the de Havilland Engine Company of the Dowty Live Line Pump as the most promising type for conversion to a fuel pump. The resulting co‐operation hd to a widening interest and in 1945 the first design schemes for a complete fuel system were initiated.

A LARGE proportion of the engines shown at the Grand Palais were either familiar types, or else they were new models of old engines. This always has to be the case, of course, but on this occasion there was a marked division between the older engines, which had mostly been in service for many years, and the new types that were for the most part completely untried. This latter fact in itself is an indication of a much more open security outlook than in the past, for the new French jet engines were exhibited before they had even carried out their bench tests.

THE export agency of this country, Omnipol, exhibited no fewer than five aircraft. One was the Avia 14, a Czech‐built Il'yushin 14 transport which was well finished and had an air of serviceability. The remaining aircraft were relatively lightweight, but of Czech design and construction.

In a combustion system for burning fluid fuel in a gaseous stream of combustion‐supporting medium, ducting immersed in the said stream and comprising first and second duct portions both extending gcnsrally in the direction of flow of said stream and enclosing between them an annular passage open at both ends, an annular ring portion extending radially from the downstream end of said second duct portion and away from said first duct portion so as to form a sudden enlargement of said annular passage, an annular fuel supply chamber comprising a wall of porous material adjoining that edge of said annular ring which is the more remote from said first duct portion and extending downstream from said edge, a third duct portion extending downstream from said annular fuel supply chamber, and a flame deflector spaced downstream from said fuel supply chamber and extending part way across said passage.

Utilizing renewable energy and developing new energy sources are practical responses to the shortage of fossil fuels and environmental regulations for carbon dioxide emissions. The purpose of this paper is to assess the practicability of using low heating value (LHV) fuel on an annular miniature gas turbine (MGT) via numerical simulations.

The MGT used in this study is MW‐44 Mark I, whose original fuel is liquid (Jet A1). Its fuel supply system is re‐designed to use biogas fuel with LHV. The simulations, aided by the commercial code CFD‐ACE+, were carried out to investigate the cooling effect in a perforated combustion chamber and combustion behavior in an annular MGT when using LHV gas. In this study, four parameters of rotational speeds are considered. At each specific speed, various mixture ratios of methane (CH₄) to carbon dioxide (CO₂) including 90, 80, 70, and 60 percent were taken into consideration as simulated LHV fuels.

The simulation results show the chamber design can create a proper recirculation zone to concentrate the flame at the center of the chamber, and prevent the flame from expanding to cause hot spot. Furthermore, the hot gas exhausted from combustor outlet is cooled down effectively by jet flow discharged from dilution holes, which prevent turbine blade from heat damage.

Simulation results demonstrate that CFD‐ACE+ can simulate flow field performance and combustion behavior in an annular MGT precisely. The results of these CFD analyses confirm that the methane fuel can be used in such small volume of MGT and still have high performance. With the aid of the constructed combustor model, the performance of a methane‐used MGT can be realized before the experiment procedure starts.

An annular combustion chamber having air jackets around its inner and outer walls, and having in combination a plurality of liquid fuel nozzles mounted in equi‐spaced relationship and circular formation around one end of the chamber with the axes of the nozzles lying centrally between the inner and outer walls of the chamber, air‐swirling means surrounding each nozzle, a hollow annular nosepiece extending from the said end of the chamber, and shaped to direct air to the air jackets, an annular air entrance situated adjacent to the outer end of the nosepiece, an annular hood surrounding the nose piece and forming therewith air passages leading from the air entrance to the air jackets, and a plurality of air scoops situated in equi‐spaced positions within the nosepiece and leading from one of the air passages to the air‐swirling means around the fuel nozzles.

Ignition process is a critical issue in combustion systems. It is particularly important for reliability and safety prospects of aero-engine. This paper aims to numerically investigate the burner-to-burner propagation during ignition process in a full annular multiple-injector combustor and then validate it by comparing with experimental results.

The annular multiple-injector experimental setup features 16 swirling injectors and two quartz tubes providing optical accesses to high-speed imaging of flames. A Reynolds averaged Navier–Stokes model, adaptive mesh refinement (AMR) and complete San Diego chemistry are used to predict the ignition process.

The ignition process shows an overall agreement with experiment. The integrated heat release rate of simulation and the integrated light intensity of experiment is also within reasonable agreement. The flow structure and flame propagation dynamics are carefully analyzed. It is found that the flame fronts propagate symmetrically at an early stage and asymmetrically near merging stage. The flame speed slows down before flame merging. Overall, the numerical results show that the present numerical model can reliably predict the flame propagation during the ignition process.

The dedicated AMR method together with detailed chemistry is used for predicting the unsteady ignition procedure in a laboratory-scale annular combustor for the first time. The validation shows satisfying agreements with the experimental investigations. Some details of flow structures are revealed to explain the characteristics of unsteady flame propagations.