EXPERIMENTAL DATA OF WAKE-INDUCED VIBRATION ANALYSIS FOR TANDEM CYLINDERS WITH SPACING RATIO OF 2.5 TO 10

Description

Data result from measurements with a condenser microphone, hot wire anemometry, and accelerometer in an aerodynamic channel to study the influence of the space ratio on the flow-induced vibration of a cylinder in a tandem arrangement. The upstream cylinder is rigidly fixed to the channel, while the cylinder placed downstream is free to vibrate transversally to the flow. The Reynolds number for the tested cases ranged between 1.12x104 to 2.29x104, based on the diameter of one cylinder, the reference velocity measured with a Pitot Tube, and the kinematic viscosity at the environmental conditions of the laboratory. 25 mm smooth cylinders with 25mm diameter made of commercial PVC tubes were used. L/D ratios tested were 2.5, 5, 8, and 10. Measurements of a single cylinder were also performed as a base case. The cylinder free-to-vibrate is attached to two blades allowing to adjust the stiffness [1]. Flow visualizations using fixed cylinders were performed in a water channel. Test section and geometry had same dimensions as the aerodynamic channel [2]; the Reynolds number was Re = 2 x 103. Dye was injected through the cylinder’s wall by gravity from two ink tanks. Video resolution was 1920 x 1080 pixels at 30 FPS. The pressure fluctuations were measured in the region between the two cylinders with a Brüel & Kjaer Cartridge type 4138 1/8” diameter condenser microphone placed at the channel upper wall, connected to an amplifier Brüel & Kjaer type 2633. Cylinder acceleration was measured with an ADXL335 analogic accelerometer, attached to the extremity of the cylinder. For the measurements of the flow velocity and velocity fluctuations, a DANTEC StreamLine constant temperature hot-wire anemometry system with a 55P11 single-wire probe placed on the wake of the second cylinder was used. Data acquisition employed an NI USB-9162 16 bits A/D board with a sampling frequency of 1 kHz and a low pass filter set at 0.3 kHz. The mass-damping parameters were equal for the single cylinder and for the arrangements with space ratio L/D = 2.5 to L/D = 8. The mass ratio was m*=539, the damping ratio ξ = 0.0169, and the natural frequency fn= 5.86 Hz. All parameters were obtained from the free vibration signal of the experimental setup. For the case of L/D = 10, the setup characteristics changed due to the increase in the length of the longitudinal gap. Data for L/D = 2.5 to L/D = 10 had a natural frequency fn= 3.906 Hz and the damping ratio was ξ = 0.011. References [1] Neumeister, R. F., Petry, A. P., & Möller, S. V. (2021). Journal of Pressure Vessel Technology, 143(3). [2] Habowski, P. B., de Paula, A. V., & Möller, S. V. (2020). Journal of the Brazilian Society of Mechanical Sciences and Engineering, 42, 1-21.

Steps to reproduce

The data set nomenclature considers the space ratio L/D (LD), the natural frequency (Fn), the Reynolds Number (Re), and the reduced velocity (Vr). The visualization videos are identified by the space ratio (LD). The uncertainty associated with the acceleration signals is about ±8% and with the velocity is between ±3% and ±5%. The uncertainties are about ±4% for the pressure fluctuations. The resulting uncertainty associated with the frequency remains around ±9%. while for the reduced velocity around ±10.5%, and for the Reynolds number about ±5%. Data are in .txt format to be read by almost all software with time [s], cylinder acceleration [m/s²], wake velocity [m/s], and pressure fluctuation [Pa]. The videos are in format .mp4. Single Cylinder Single_Fn=5.86Hz_Re=1.15x104_Vr=48.txt Single_Fn=5.86Hz_Re=1.76x104_Vr=75.txt Single_Fn=5.86Hz_Re=2.29x104_Vr=97.txt SingleCylinder.mp4 LD = 2.5 LD2.5_Fn=3.91Hz_Re=1.12x104_Vr=72.txt LD2.5_Fn=3.91Hz_Re=2.23x104_Vr=142.txt LD2.5_Fn=5.86Hz_Re=1.15x104_Vr=48.txt LD2.5_Fn=5.86Hz_Re=1.76x104_Vr=75.txt LD2.5_Fn=5.86Hz_Re=2.29x104_Vr=97.5.txt VisualisationLD2.5.mp4 LD = 5 LD5_Fn=3.90Hz_Re=1.12x104_Vr=71.txt LD5_Fn=3.90Hz_Re=2.23x104_Vr=142.txt LD5_Fn=5.86Hz_Re=1.15x104_Vr=49.txt LD5_Fn=5.86Hz_Re=1.76x104_Vr=75.txt LD5_Fn=5.86Hz_Re=1.76x104_Vr=75.txt VisualisationLD5.mp4 LD = 8 LD8_Fn=3.90Hz_Re=1.12x104_Vr=71.txt LD8_Fn=3.90Hz_Re=2.23x104_Vr=142.txt LD8_Fn=5.86Hz_Re=1.15x104_Vr=48.txt LD8_Fn=5.86Hz_Re=1.73x104_Vr=75.txt LD8_Fn=5.86Hz_Re=2.27x104_Vr=97.txt VisualisationLD8.mp4 LD = 10 LD10_Fn=3.91Hz_Re=1.12x104__Vr=72.txt LD10_Fn=3.91Hz_Re=2.27x104_Vr=142.txt VisualisationLD10.mp4

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