Improved Models for Prediction of Locally Intense Aeroacoustic Loads and Vibration Environments

ATA Engineering, Inc. proposes an STTR program to develop innovative tools and methods that will significantly improve the accuracy of random vibration response predictions for aerospace structures under critical inhomogeneous aeroacoustic loads. This will allow more accurate predictions of structural responses to be made, potentially reducing vehicle weight and cost and improving the reliability of these structures. Empirical wind tunnel test data will be used as a basis to develop innovative methods to characterize the surface fluctuating pressures encountered by launch vehicles during ascent, and then to accurately predict the random vibration environment caused by these loads. The wind tunnel test will measure both the surface fluctuating pressure and the resulting vibration in a flexible panel. Phase I will be spent performing pre-test engineering to reduce Phase II risk, generating drawings for construction of test articles, and deriving the test matrix for the Phase II wind tunnel test. The objective of Phase I is to demonstrate that the proposed Phase II wind tunnel test will be able to provide the test data necessary to improve predictions of fluctuating pressures and random vibration during ascent. Phase II will be used to perform the wind tunnel tests for compression corners, expansion corners, and protuberances. The vibration and fluctuating pressure data from these tests will be used to develop more accurate models to predict the auto- and cross-spectra of surface fluctuating pressures during ascent, followed by the development of coupling models to predict the resulting spacecraft structural vibrations. A critical improvement over current methods will be the inclusion of a statistical basis which will enable prediction of both mean and maximum expected environments. The experimental data in Phase II will also be made available to other researchers performing unsteady computational fluid dynamics simulations as validation data.

The methods and embodying software that will be developed under this project will provide unprecedented accuracy in predicting aeroacoustic loading and vibration response for any spacecraft or launch vehicle during ascent. One of the most noteworthy and immediate opportunities for infusion of this technology is in the design of NASA's Space Launch System (SLS), an advanced heavy-lift launch vehicle being developed. The SLS will deliver the Orion Multi-Purpose Crew Vehicle to space and will be involved in a number of commercial and International Space Station missions. The technologies proposed do not carry much risk and provide an opportunity early in the development process to make design decisions that can result in significant increases in affordability, reliability, and performance. Additionally, the design of systems and components aboard more near-term NASA spaceflight missions will benefit from the improved predictive capability, with specific examples including the proposed series of Flagship Technology Demonstration launches, the constellation of CYGNSS spacecraft, and InSight and other prospective Mars missions. The proposed technology directly addresses the high-priority challenge for "analytical capabilities that go far beyond existing modeling and simulation capabilities and reduce use of empirical approaches in vehicle design" identified in NASA's Space Technology Roadmap for Technology Area 11: Modeling, Simulation, Information Technology, & Processing.

As the aerospace industry adapts to the retirement of the Space Shuttle, it stands poised at the beginning of a new era of space exploration and commercial space activities. Numerous private sector companies are developing the next generation of commercial launch vehicles, space station resupply services, and spacecraft for the suborbital space tourism market. A common theme for these new systems is that they feature innovative designs that make a marked departure from the legacy spaceflight and rocket systems employed in the last half decade of orbital launches. New concepts such as Virgin Galactic's SpaceShip Two spaceplane and SpaceX's nine-engine Falcon 9 rocket provide a host of new vibroacoustic scenarios that must be understood and addressed as part of certifying payload survivability or human passenger safety. By enabling more accurate prediction of the vibroacoustic response of these systems, the methods developed in this project will contribute to the design of more efficient and reliable systems while reducing the mission risk from unaccounted aeroacoustic loads. ATA will make this technology available to industry by offering engineering consulting services and specialized software.

This is early/mid-stage (TRL 4) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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