Experimental and numerical investigation of spray characteristics in a new FLOX^®based combustor for liquid fuels for Micro Gas Turbine Range Extender (MGT-REX)

Abstract

A liquid fuel combustor based on the FLOX ® gas turbine burner concept has been developed for application in a Micro Gas Turbine (MGT) Range Extender (REX) for next generation cars. The characterization of this combustor was performed at the High Pressure Optical Test rig (HIPOT) at DLR Stuttgart. Spray characteristics were measured using droplet mie scattering and phase Doppler interferometry in flames of a stable burner operation point (BOP) at a pressure, preheat temperature, global lambda (G), and jet velocity of 3.5 bars, 300 °C, 1.45 and 120 m/s respectively. The experimental results showed long flames with deep penetration of the spray into the combustion chamber. A comprehensive data set of the spray characteristic with well-defined boundary condition was made available for CFD simulations. The CFD simulation of the two-phase flow was performed by coupling the DLR liquid phase simulation code SPRAYSIM with the commercial CFD-code ANSYS CFX-16.1. The comparison of axial and radial velocity profiles between simulation and experiment clearly showed that the turbulence model used in the numerical simulation was unable to predict the measured turbulence appropriately. The calculated and measured spray behavior in the combustion chamber showed satisfying agreement. The observed differences were mainly due to the simple 1-step global combustion model, which predicted an early onset of the heat release. The simulation showed that even though a large portion of the evaporation happened already inside the nozzle, the remaining spray droplets penetrate deep into the combustion chamber.

Experimental Investigation of Flame Stabilization in a Turbulent Premixed Recirculation-Stabilized Jet-Flame with Simultaneous kHz Laser Diagnostics

“…The spectrum rather is an almost ideal homogeneous turbulence. The energy dissipation towards higher frequencies follows the slope of − 5 3 , which is predicted by theory. 19 At lower frequencies in the orders of 10 1 and 10 2 Hz, the velocity fluctuations of the axial component k y are much higher than the lateral components k x and k z , which are of similar magnitude.…”

“…3 Furthermore, they qualify for an operation with a large variety of both gaseous and liquid fuels. 1,[4][5][6] RSJF are used in FLOX gas turbine combustors, 1,2,7 which consist of nozzles circularly arranged on the burner base plate. These nozzles feed partially premixed air and fuel into the combustion chamber at high velocity (e.g.…”

Numerical and Experimental Study of a Jet-and-Recirculation Stabilized Low Calorific Combustor for a Hybrid Power Plant

“…Combustion dynamics and thermoacoustic phenomena were analyzed by means of experiments [34] and numerics [35], only to name a few. A later adaption in view of possible aero-engine applications was the transition to liquid fuel operation [36][37][38]. Explicit developments for aero-engine applications are subject to on-going studies [39].…”

Experimental Investigation of the Combustion Behavior of Single-Nozzle Liquid-FLOX®-Based Burners on an Atmospheric Test Rig

“…Some research studies have previously been conducted on FLOX ® -based burners. In particular, experiments conducted by Gounder, et al [9] studied the spray characteristics in a new liquid fuel 8-nozzle FLOX ® -based combustor for MGT applications. Gounder's investigation showed a stable flame at high jet velocity and lambda-based global air equivalence ratio of vnozzle = 120 m/s and λ = 1.45, respectively.…”