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Tesi etd-09122018-155725


Tipo di tesi
Tesi di laurea magistrale
Autore
ACCORINTI, ALESSANDRO
URN
etd-09122018-155725
Titolo
PIV measurements of Turbine Rear Structure flow
Struttura
INGEGNERIA CIVILE E INDUSTRIALE
Corso di studi
INGEGNERIA AEROSPAZIALE
Commissione
relatore Prof.ssa Salvetti, Maria Vittoria
relatore Prof. Buresti, Guido
tutor Prof. Chernoray, Valery
Parole chiave
  • POD
  • Experiments
  • PIV
  • Turbomachinery
  • LPT
  • TRS
  • OGV
Data inizio appello
02/10/2018;
Consultabilità
parziale
Data di rilascio
02/10/2021
Riassunto analitico
The flow field characteristics of a TRS (turbine rear structure) have been experimentally<br>investigated using the non-intrusive PIV (particle image velocimetry)<br>technique. The TRS is the structure located downstream of the LPT (low-pressure<br>turbine) in a jet engine. The flow features through this structure are extremely<br>complex since non-uniformities generated at the LPT interact with the OGVs (outlet<br>guide vanes) located inside this structure.<br>The experiments were conducted at the Chalmers Fluid Mechanics department<br>wind tunnel, which consists in a closed loop facility where an LPT is located upstream<br>of the test section to provide engine-realistic inlet boundary conditions to<br>the TRS.<br>In particular, the measurements involved the three following regions of the flow:<br>the outlet of the TRS (2D and stereo PIV), Plane B (stereo PIV) and the boundary<br>layer around the single OGV of the TRS (2D PIV).<br>Moreover, the experiments were conducted varying the value of two coefficients.<br>The first one is the Reynolds number based on the channel height. Two values<br>were tested corresponding to the low and high speed respectively: Re = 235000<br>and Re = 465000.<br>The second one is the flow coefficient that is defined as the ratio between the axial<br>velocity of the flow and the rotational speed of the turbine. Four different values<br>of this coefficient were tested in the whole experimental campaign: 0.588, 0.622,<br>0.657 and 0.775.<br>Several quantities of interest were calculated from the data recorded through the<br>software Dynamic Studio 2016-a, such as the instantaneous velocity and vorticity<br>fields but also the main statistics (mean velocity field, standard deviations of velocity<br>components etc.).<br>Afterwards, a POD (Proper Orthogonal Decomposition) analysis was applied to<br>the data to investigate the presence of relevant modes.<br>Finally, an FFT transform analysis was conducted to make a comparison with the<br>POD results.<br>To conclude, the quality of the results can be deemed satisfactory, considering<br>that new measurements will be taken in the near future. However, the presence<br>of technical issues such as multiple reflections coming from the internal structure<br>of the TRS or low images recording sampling frequency led to an only partial<br>comprehension of the complex phenomena happening inside the TRS.
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