Low-density multi-fan wind tunnel design and testing for the Ingenuity Mars Helicopter

Marcel Veismann, Christopher Dougherty, Jason Rabinovitch, Amelia Quon, Morteza Gharib

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Prior to its successful flights on Mars, the Ingenuity Mars Helicopter system underwent extensive flight dynamics testing in the 25-ft Space Simulator facility, a low pressure environmental chamber at NASA’s Jet Propulsion Laboratory (JPL), which can re-create relevant Martian conditions on Earth. This facility, while large, is not large enough for free or tethered forward flight tests. In this work, an open-jet, multi-fan wind tunnel concept is presented, which was integrated into the JPL facility to simulate the external freestream flow of forward flight scenarios in a low-density environment. A theoretical and experimental analysis was performed to evaluate the possibility of utilizing commercially available 80 x 80 mm axial flow cooling fan units for this type of wind tunnel. Sub-scale tests found that under Martian conditions, fans deliver approximately 30% reduced flow rates for the same RPM compared to Earth conditions due to decreased efficiencies at low Reynolds numbers. However, fans can run at higher RPM in low-density fluids, with the RPM increase being specific to the fan motor. While power consumption dropped by more than 90%, fans experienced higher thermal loads due to reduced heat convection. The study concludes that the investigated type of cooling fan can operate without modification in a low-density environment, offering a low-cost and easily adaptable wind tunnel solution. Informed by ambient flow field measurements on a comparable multi-fan wind tunnel, a low-density full-scale facility with 441 individually controlled fan units was constructed and used for aerodynamic testing of an engineering model of Ingenuity. Graphic abstract: [Figure not available: see fulltext.].

Original languageEnglish
Article number193
JournalExperiments in Fluids
Volume62
Issue number9
DOIs
StatePublished - Sep 2021

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