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Flow past a circular cylinder is a problem for understanding flow around bluff bodies. This flow has been studied both experimentally and numerically of laminar infinite flow of viscous incompressible fluid around a rotating circular cylinder at Reynolds number 80,120,160 and dimensionless rotation rate, α , (ratio of cylinder surface speed to the free stream velocity) varying from 0 to 6 has been carried out. Navier–Stokes and continuity equations were solved numerically by using finite volume technique is conducted with ANSYS CFX 15 package program. High Speed Photography and LDV, present new experimental results for correlation purposes, captured the flow profile. Rotation can be used as a drag reduction technique. Comparison with previous studies showed good agreement.

‘Fuel-flexible’ gas turbines will be required over the next 20 years at least. However, this contrasts with recent experiences of\ud global operators who report increasing emissions and difficult combustion dynamics with even moderate variations in the fuel\ud supply. Swirl stabilized combustion, being the most widely spread technology to control combustion in gas turbines, will be a\ud technology needed for dynamic stabilization of the flow field. However, the features of the recirculation zone are highly complex,\ud three dimensional and time dependent, depending on a variety of parameters. A high momentum flow region inherent to swirling\ud flows has attracted the attention of several groups interested in blowoff and stretch flame phenomena. Therefore, this study\ud focuses on experimental results obtained to characterise the relation between the central recirculation zone and the high momentum\ud flow region under moderate swirl levels using a well-studied tangential swirl burner for power generation applications. As\ud to be expected the recirculation zone and the high momentum flow region rotate together about the central axis. Moreover, the\ud interaction between them produces high, intense local velocities. This region of High Momentum (shearing flow) also presents a\ud complex geometry that seems to be based on the geometrical features of the burner, different to previous findings on the burner\ud where the system was thought to have a unique shearing flow region. The high three dimensional interaction of these structure is\ud confirmed at the point where the precessing vortex core losses its strength.

Lean premixed combustion using swirling flows is widely used in gas tur\ud -\ud bines and combustion. Although flashback is not generally a problem with\ud natural gas combustion, there are some reports of flashback damage with\ud existing gas turbines, whilst hydrogen enriched fuel blends cause concerns\ud in this area. Thus, this paper describes a practical approach to study and\ud avoid flashback in a pilot scale 100\ud kW tangential swirl burner. The flash\ud -\ud back phenomenon is studied experimentally via the derivation of flashback\ud limits for a variety of different geometrical conditions. A high speed camera\ud is used to visualize the process and distinguish new patterns of avoidance.\ud The use of a central fuel injector is shown to give substantial benefits in terms\ud of flashback resistance. Conclusions are drawn as to mitigation technologie

This paper discusses the context for the use of biomass for electricity generation in the UK and similar markets and evaluates the possibility of using cyclonic gasification coupled to small gas turbine systems. In the UK the Government has strongly pushed for a significant increase in the use of renewable energy for electricity generation with only very modest success, nearly 3% coming from this source at present, predominantly hydro and wind. Subsidy for the early tranches of these systems came from an elevated price for generated electricity, but since attempts at price convergence with that pertaining with conventional fossil fuel generation systems has occurred the number of biomass systems being constructed and their net generating capacity has not increased in line with other technologies. Although utilisation technologies exist, and are well proven technologically in Scandinavia, when translated to markets such as the UK, give generating costs which are not competitive with other forms of renewable energy. Problems have arisen with many systems, being predominantly due to fouling/slagging, the different nature of the fuels, and elevated moisture content.\ud In this context this paper describes an EU sponsored programme of work to develop a simple cyclone gasifier and combustor which can produce a medium calorific fuel gas for materials such as sawdust, retain up to about 80% of the total ash/residues in the system, and fire simple, low cost gas turbines for power generation. The system is shown to have a very wide operating range and can handle sawdust with significant quantities of material up to 4mm in size, whilst tolerating significant variation in moisture content and capturing very significant quantities of the ash/particulate matter as well as volatile species.

This paper presents a series of experiments and numerical simulations using commercial software (ANSYS) to determine the behaviour and impact on the blowoff process with various geometries and simulated syngas compositions at fixed power outputs. Experiments were performed using a generic premixed swirl burner. The Central Recirculation Zone and the associated turbulent structure contained within it were obtained through CFD analyses providing details of the structures and the Damkolher Number (Da) close to blowoff limits. The results show how the strength and size of the recirculation zone are highly influenced by the blend, with a shift of Da and turbulence based on carbon-hydrogen ratio, shearing flows and Reynolds number. Instabilities such as thermoacoustics, flashback, autoignition and blowoff are highly affected by the flow structures and chemical reactions/diffusivity. Moreover, it has been observed that turbulence close to the boundaries of the central recirculation zone, a region of high stability for swirling flows, is highly altered by the chemical characteristics of the fuel blends. In terms of blowoff, the phenomenon is still not entirely understood. As the process occurs, its theoretical limits do not match its real behaviour. Therefore, one possibility could be the difference in turbulence and Da numbers across the flame, being critical at the base of the flame where the system is stabilized.