The atmosphere of Venus is 96% carbon dioxide and&nbsp;contains&nbsp;clouds of sulfur dioxide and sulfuric acid, with&nbsp;surface temperatures&nbsp;in excess of&nbsp;470 degrees Celsius and&nbsp;pressures&nbsp;92 times that of Earth. These extreme environmental conditions make planetary exploration difficult as modern electronics&nbsp;cannot survive&nbsp;for&nbsp;prolonged periods&nbsp;of time. Photovoltaics, a conventional&nbsp;power generation&nbsp;method for&nbsp;Mars&nbsp;rovers, are inefficient&nbsp;on the planet’s surface due to the dense cloud cover and&nbsp;harsh environment. The NASA – JPL&nbsp;Hybrid&nbsp;Automaton Rover&nbsp;Venus&nbsp;proposes using&nbsp;a mechanical wind&nbsp;energy&nbsp;harvester to further explore the Venusian surface.&nbsp;At&nbsp;the proposed landing site, the surface wind speeds range from 0.3 to 1.3 m/s with an average wind speed of 0.6 m/s. These wind speeds,&nbsp;combined with&nbsp;the&nbsp;high density of Venusian air,&nbsp;results in promising potential for power generation. The power goal for the proposed wind harvester is 9W at the average wind speed of 0.6 m/s.&nbsp;A horizontal axis turbine is used to avoid dynamic stall experienced by vertical axis wind turbines at&nbsp;low wind speeds.&nbsp;In&nbsp;the&nbsp;horizontal axis wind turbine design, existing airfoil profiles were evaluated and chosen using&nbsp;QBlade.&nbsp;The blade designs were analyzed using blade element momentum theory&nbsp;(BEM) and computational fluid dynamics (CFD) to predict and improve turbine&nbsp;performance.&nbsp;Small-scale wind turbines were&nbsp;3D printed, post-processed, and tested in&nbsp;a&nbsp;subsonic&nbsp;wind tunnel. Wind tunnel testing was performed to test the validity of our design tools.&nbsp;Subsequent testing was performed in&nbsp;water,&nbsp;as the greater&nbsp;fluid&nbsp;density allowed for testing at lower speeds to&nbsp;better&nbsp;simulate Venus surface conditions.&nbsp;&nbsp;The&nbsp;preliminary&nbsp;water&nbsp;testing was carried out to characterize turbine performance.&nbsp;In this&nbsp;process, a 3D printed&nbsp;1:4 scale&nbsp;turbine was placed in an&nbsp;open-channel&nbsp;pool&nbsp;with&nbsp;flow supplied&nbsp;through a pump. The turbine was a fixed 2.33&nbsp;m&nbsp;distance away from the inlet of the flow. The flow speed, turbine rotational speed, and torque produced were recorded. The results yielded turbine efficiencies between 7.7% and 53.9% in the range of tip speed ratios&nbsp;(TSR) tested.&nbsp;These results exceeded design expectations,&nbsp;at&nbsp;the&nbsp;designed&nbsp;TSR,&nbsp;where&nbsp;an&nbsp;efficiency&nbsp;of 40% was&nbsp;to&nbsp;be expected.&nbsp;&nbsp;Based on the preliminary results,&nbsp;modifications are being made&nbsp;to the water&nbsp;testbed&nbsp;to improve the testing process as well as&nbsp;more accurately simulate conditions&nbsp;on the surface of&nbsp;Venus. The collected data and the&nbsp;aforementioned design&nbsp;tools are used to improve the current turbine design.&nbsp;

Design of a Horizontal Axis Wind Turbine for a Venusian Environment

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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