Aeroelasticity and Experimental Aerodynamics · Aeroelasticity and Experimental Aerodynamics...
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Aeroelasticity and Experimental Aerodynamics AERO0032-1 December 2017 Aeroelastic analysis of a square cylinder 1 Introduction During this lab, wind tunnel measurements are carried out on square cylinder free to oscillate verti- cally with the objective to analyse its aeroelastic behaviour. The aluminum cylinder has an external side of 50mm, a thickness of 2mm and a length of 1340mm. It is supported by four extension springs are connected to a fixed frame bolded to the ceiling of the test section. In addition, elastomers can be connected to the model on each side (see figure 1). The stiffness in flexion in the vertical direction is equal to 8683N/m and 8359N/m for the cases with and without the elastomers mounted respectively. The square cylinder is held horizontal at an angle of attack of zero degree. It is instrumented with a three components accelerometer measuring the acceleration along x,y, and z (acquisition frequency is set to 102.4Hz). A vane anemometer measures the wind velocity seen by the model. Figure 1: Experimental set-up
Transcript of Aeroelasticity and Experimental Aerodynamics · Aeroelasticity and Experimental Aerodynamics...
Aeroelasticity and Experimental Aerodynamics
AERO0032-1
December 2017
Aeroelastic analysis of a square cylinder
1 Introduction
During this lab, wind tunnel measurements are carried out on square cylinder free to oscillate verti-cally with the objective to analyse its aeroelastic behaviour. The aluminum cylinder has an externalside of 50mm, a thickness of 2mm and a length of 1340mm. It is supported by four extension springsare connected to a fixed frame bolded to the ceiling of the test section. In addition, elastomers can beconnected to the model on each side (see figure 1). The stiffness in flexion in the vertical direction isequal to 8683N/m and 8359N/m for the cases with and without the elastomers mounted respectively.The square cylinder is held horizontal at an angle of attack of zero degree. It is instrumented with athree components accelerometer measuring the acceleration along x,y, and z (acquisition frequency isset to 102.4Hz). A vane anemometer measures the wind velocity seen by the model.
Figure 1: Experimental set-up
2 Structure of the data
The measurements performed during the lab by each group and additional measurements have beenpre-processed and compiled into a Matlab file (DATAGi.mat). Each group uses its own mea-surement files. The Matlab file contains a structure array, named exp data Gi with the followingcharacteristics:
• U field, gathering the different airspeeds tested during the lab in m/s (available for wind ontests only).
• e field, gathering the information about the presence (e=1) of elastomers or not (e=0).
• xddot, yddot, zddot fields, corresponding to the acceleration, measured in the streamwisedirection (x), spanize direction (y) and vertical direction (z). Accelerations are expressed inm/s2.
3 Questions
The following questions must be answered (each group uses its own data):
1. Identify the modal properties of the structural cylinder.
2. Analyse the frequency content of the signals vs wind speed.
3. Discuss the effect of the elastomers on the aeroelastic system.
4. Evaluate the critical velocities of VIV and galloping and compare to your experimental results.
5. Identify the two major VIV outputs of this wind tunnel test campaign.
6. Perform the adapted non-dimensionalization to compare your results with the ones of the lecturenotes.
7. Discuss the potential interference between VIV and galloping on the basis of your results.
4 Practical details
One report per group must be provided by Friday 29 December 2017. This report must belimited to 5 pages (be concise, no reading after page 5). It must be sent in pdf format [email protected] with the subject: AERO0032-1: Lab 2: report group #.
5 Groups, schedule and location
The lab session takes place at the Wind Tunnel Laboratory on Thursday 7th December 2017. Thelocation of the lab can be found here. Students are invited to take part to the lab by group.
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