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The hydrodynamic stability of the radial Rayleigh-Benard-Poiseuille flow inside the collector of solar chimney power plants has not attracted much attention in the literature. Because the ground is heated, buoyancy driven instability is possible. In addition, viscosity driven instability may occur. Temporal and spatial simulations are employed for investigating the hydrodynamic stability of the radial flow. Towards this end a new compact finite difference Navier-Stokes code is being developed. Square channel ow simulations were performed for code validation purposes using both the new code and an existing finite-volume code. For certain Reynolds and Rayleigh number combinations transverse rolls or longitudinal rolls appear while for others the ow remains stable. A Fourier mode decomposition of the wall-normal velocity component at mid-channel height reveals linear (exponential) growth for the unstable modes and nonlinear interactions once the mode amplitudes exceed a certain threshold. The present square channel flow results are consistent with the neutral curves from the linear stability theory analysis by Gage and Reid. Simulations were also carried out for the collector of a 1:30 scale model of the Manzanares solar chimney power plant at the University of Arizona. The Rayleigh number is well above the critical Rayleigh number and steady longitudinal rolls appear shortly downstream of the collector inflow.
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Experimental and Numerical Investigation of a Roof-Scale Solar Chimney
This paper reports on an experimental investigation of the flow through the collector of a solar chimney power plant which has been constructed on the roof of the Aerospace and Mechanical Engineering building at the University of Arizona. This model contains a central chimney which is a long tubular structure located in the center and a circular collector that employs the greenhouse effect to heat up the air under it. The chimney is 5.9m high and the collector radius measured from the center of the chimney is 4.13m. Measurements were carried out from April to June 2019. Several types of J thermocouples were mounted inside the collector at various radial locations to measure the air temperature both near the ground and the ceiling of the collector. A hot-wire probe (anemometer) was employed to measure the airflow velocity under the collector near the chimney inlet. A traverse system was designed and constructed, which allows the anemometer to be moved in the radial and circumferential direction under the collector. The height of the probe position above the collector ground can be adjusted by rotating the probe support along its longitudinal axis. A digital analog conversion system was used to convert the thermocouple and hot-wire readouts into binary data for processing via a LabVIEW interface. In parallel to the experiments, high-fidelity numerical simulations are being carried out for the conditions of the experiments. The simulations show longitudinal flow structures near the collector outflow that likely result from a buoyancy-driven instability.
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- Award ID(s):
- 1510179
- PAR ID:
- 10180776
- Date Published:
- Journal Name:
- AIAA Scitech 2020 Forum
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.2514/6.2020-0838
