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Published September 2021 | metadata_only
Journal Article

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


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.

Additional Information

© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2021. Received 30 April 2021; Revised 15 July 2021; Accepted 25 July 2021. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement by the United States Government or the Jet Propulsion Laboratory, California Institute of Technology. The authors would like to thank the JPL Ingenuity Team for the implementation of the low-density wind tunnel in the 25-ft chamber. The authors additionally wish to thank various people for their contribution to this project: Alejandro Stefan Zavala, for developing the operating software for the wind tunnel systems; Peter Renn, for assisting during the ambient flow measurements; Manuel Gallegos, for the sub-scale system chamber integration and testing; and Dave Natzic, for his assistance during the sub-scale chamber tests. The authors would also like to thank associate editor Jerry Westerweel, and reviewers Ralph Lorenz and an anonymous reviewer for their constructive feedback that substantially improved the quality of this manuscript. Parts of this research were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). Author Contributions: Conceptualization: Jason Rabinovitch; Methodology: Marcel Veismann, Christopher Dougherty, Jason Rabinovitch; Formal analysis and investigation: Marcel Veismann, Christopher Dougherty, Jason Rabinovitch; Writing—original draft preparation: Marcel Veismann; Writing—review and editing: Marcel Veismann, Christopher Dougherty, Jason Rabinovitch; Funding acquisition: Jason Rabinovitch; Resources: Jason Rabinovitch; Supervision: Morteza Gharib, Amelia Quon. The authors declare that they have no conflict of interest. Code availability: Not applicable.

Additional details

August 20, 2023
August 20, 2023