Aerodynamics of an isolated slot-burner from a tangentially-fired boiler

Abstract

a b s t r a c tThe aerodynamic development of fully turbulent isothermal jets issuing from rectangular slot-burners was modelled by obtaining a solution to the Reynolds averaged Navier-Stokes equations. A finite-volume method was used with the standard k-e, RNG k-e and Reynolds stress turbulence models. The slot-burners were based on physical models, which were designed to be representative of typical burner geometries found in tangentially-fired coal boilers. Two cases were investigated, in which jets from three vertically stacked rectangular nozzles discharged at 90°and then 60°to the wall containing the burner. The nozzle angle had little effect on jet centreline velocity decay, with the 60°nozzle showing a marginally higher rate of decay. The jets from the 60°nozzles were found to deviate slightly from their geometric axis slightly due to internal pressure redistribution in the flow at the nozzles. The simulations were validated against the physical models and were found to reproduce the flow field of the jets accurately with the Reynolds stress model producing the best results.

Simulation of Improvements to In-cylinder Mixing of Biodiesel with Air by Incorporating Guide Vanes into the Air Intake System

“…Improved swirl and tumble within the air flow at the fuel injection area between the start of injection (SOI) and start of combustion (SOC) is expected to aid the mixing of biodiesel and air, and the increased air velocity in the injection area is expected to impart velocity to the molecules of biodiesel. This swirling vortex of air will result in better air and fuel mixing and higher combustion efficiency [16]. This article will present the results of simulations of the air and biodiesel flows within cylinders for engines with and without the GVSTD, in order to assess the effectiveness of the device.…”

Investigation of Slot-Burner Aerodynamics with Recessed-Type Nozzle Geometry

“…Fluid is entrained from the surroundings into the separated regions and into the base regions between the jets. Geometrically-similar jets exhibit similar behaviour when the Reynolds number is above 2.5ˆ10 4 [15]. Therefore, the model burner jets should exhibit an aerodynamic behaviour similar to a full-sized burner jet, taking into consideration the previous comments on the effects of compressibility and temperature, as well as the isolated nature of the model burners compared to the a real burner, which experiences cross-flow due to neighbouring burners and the furnace's central vortex.…”

“…The details of all other geometries are documented in [15]. The physical model is approximately 1/30th the geometric scale of a real burner nozzle, with the Reynolds number maintained at around 1.0ˆ10 5 .…”

Numerical and experimental investigations on the physical characteristics of supersonic steam jet induced hydrodynamic instabilities

“…The thermal hydraulic instabilities in boiling channels have been investigated [8] by using RELAP5 code. [10] Not only the effect of the nozzle angle on the jet centerline velocity decay has been found, but also the simulations were validated against the physical models and were found to reproduce the flow field of the jets accurately with the Reynolds stress model producing the best results. The aerodynamic development of fully turbulent isothermal jets issuing from rectangular slot-burners was modeled by obtaining a solution to the Reynolds averaged Navier-Stokes equations.…”

“…The aerodynamic development of fully turbulent isothermal jets issuing from rectangular slot-burners was modeled by obtaining a solution to the Reynolds averaged Navier-Stokes equations. [10] Not only the effect of the nozzle angle on the jet centerline velocity decay has been found, but also the simulations were validated against the physical models and were found to reproduce the flow field of the jets accurately with the Reynolds stress model producing the best results. The behavior of two-phase flow instabilities in a twin channel system has been discussed [11] elsewhere.…”