Giordano Tanzini

LDA and PIV velocity measurements in free jets

Abstract Velocity measurements on axisymmetric jets are performed with both laser-Doppler anemometry (LDA) and particle image velocimetry (PIV). Two geometric configurations are investigated: circular and annular jets in still ambient fluid. The results obtained with the two measuring techniques are compared and related to the results of self-preservation theories. To describe mixing properties of the tested geometric configurations, vorticity plots are also calculated from PIV measurements: the results are useful for optimal design of efficient burners.

Development and Experimental Testing of a Pilot Burner for DLN Combustors

Different geometrical modifications have been investigated and experimentally tested to improve a pilot burner for low emission industrial gas turbine combustors. Results of the ongoing collaboration between the DE of Florence and the Italian electric company ENEL are reported. The activity is dedicated to the improvement of the pilot burner to extend the operable margin of the engine and to reduce, at the same time, the emissions. The study has been performed mainly by means of experimental investigations both on isothermal flow as on combustion test rig. Results of the activity were employed both to obtain design information about the swirler and injection fuel holes for the pilot burner under investigation. Moreover the post-processing of the experimental data permitted the improvement of the correlation implemented into the 1-D model for the prediction of the injected fuel path. These results were implemented in the routine DoFHIS (Design of Fuel Holes Injection Systems) developed for the analysis/design of injection fuel systems.Copyright

Velocity Measurements and Gas Mixing Characterization at the Exit of an Isothermal Model of a Gas Turbine Premixer

Premixed flames have shown to provide sufficient low NOx emission levels in gas turbine combustor. To achieve this goal several issues are to be addressed. Highly uniform fuel air ratio along with proper velocity profiles at the flame front has to be achieved. Vortex generators are commonly employed inside lean premixed combustor to generate a swirling flow that can assure the two aspects above. An experimental parametric study of the isothermal swirl flow of a non-confined prototype premixer is presented. Several different geometrical details have been considered for two different fuel air ratios. Velocity fields and mixing distribution between fuel and air at the premixer exit are described. Velocity and turbulence data can be related to formation of flashback and temporal homogeneity of the mixture respectively while the degree of spatial mixing, in terms of segregation factor, is connected with NOx rate of formation. In both cases the vigorous and high responsive character of the vortex generated by the swirler plays a major role. The final objective is twofold: to define an optimum geometrical arrangement to be tested in subsequent combustion tests and to demonstrate the feasibility of a rapid assessment method of degree of mixing between fuel and air.Copyright

LDA AND PIV VELOCITY MEASUREMENTS IN FREE JETS

Velocity measurements on axisymmetric jets are performed with both Laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV). Two geometrical configurations are investigated: circular and anular jets flowing in free environment. The results obtained with the two measuring techniques are compared between them and with theoretical results. From PIV measurements vorticity plots are also calculated.

Visualizing and Charactering Free Jets Flow with Laser Velocimetries

During last years the use of whole field velocimetry techniques in fluid flows overlays the limits of single point measurements (HWA, HFA, LDA etc.). The enhancements in image recording and processing gave advantages to optical over classical methods. If the interest is focalized on velocity measurements, several new methods can be employed: Holographic Interferometry [1]; Doppler Global Velocimetry (DGV) [2]; Particle Image Velocimetry (PIV) [3, 4].