A model for NOx emissions from turbulent premixed and partially premixed flames in gas turbines combustors is developed. The model is based on splitting NOx formation into a fast (”prompt”) high Damk¨ohler number and a slow (”postflame”) low Damk¨ohler number contributions. A novel idea is presented for modelling prompt NOx. Given their development within the narrow heat release region (flamelet), prompt NOx are modelled coupled to heat release, i.e. according to a flamelet type combustion model. Postflame NOx are accounted for via direct incorporation of a formation rate obtained from the Zeldovich mechanism, integrated with a presumed shape probability density function (pdf) of the fuel mixture fraction f. The model is incorporated into a commercial 3D-CFD solver and shown to give reasonable agreement with NOx experimental data measured from flames stabilized in the ALSTOM EV double cone burner. The model is also incorporated into a less computationally expensive reactor network using detailed chemistry where unmixedness levels at the flame are obtained from CFD results or experiments. The proposed split of NOx into the prompt and postflame contributions gives finally the opportunity to explain observed experimental dependency of total NOx from pressure and unmixedness.
Biagioli F., De Pascale A., Guthe F. (2005). Modelling NOx emissions for lean partially premixed flames in industrial burners. s.l : s.n.
Modelling NOx emissions for lean partially premixed flames in industrial burners
DE PASCALE, ANDREA;
2005
Abstract
A model for NOx emissions from turbulent premixed and partially premixed flames in gas turbines combustors is developed. The model is based on splitting NOx formation into a fast (”prompt”) high Damk¨ohler number and a slow (”postflame”) low Damk¨ohler number contributions. A novel idea is presented for modelling prompt NOx. Given their development within the narrow heat release region (flamelet), prompt NOx are modelled coupled to heat release, i.e. according to a flamelet type combustion model. Postflame NOx are accounted for via direct incorporation of a formation rate obtained from the Zeldovich mechanism, integrated with a presumed shape probability density function (pdf) of the fuel mixture fraction f. The model is incorporated into a commercial 3D-CFD solver and shown to give reasonable agreement with NOx experimental data measured from flames stabilized in the ALSTOM EV double cone burner. The model is also incorporated into a less computationally expensive reactor network using detailed chemistry where unmixedness levels at the flame are obtained from CFD results or experiments. The proposed split of NOx into the prompt and postflame contributions gives finally the opportunity to explain observed experimental dependency of total NOx from pressure and unmixedness.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
