Abstract
With the explosive growth of space debris, collisions among space debris and spacecrafts seem to be inevitable, which may greatly threaten the structure of on-orbit spacecrafts as well as astronauts’ safety. It is of crucial importance to locate the leak source and evaluate the corresponding damage quickly and accurately to ensure the safety of astronauts and spacecraft equipment. It is widely accepted that acoustic emission method can be used to detect on-orbit leak for space station; however, accurate prediction of vacuum leak noise in space station is difficult as jet and jet noise in vacuum environments are different from those in terrestrial environment. Therefore, this paper tries to investigate sound generations of vacuum leak jet by numerically analyzing dynamics of unsteady vacuum jet flow. Specifically, numerical simulation based on realizable k-ε model is adopted to study the aerodynamic properties and the aeroacoustic characteristics. Results show that RANS turbulent model can capture the pressure fluctuation with high computation efficiency and acceptable accuracy. Secondly, leak from 1 atm to vacuum forms a supersonic flow with Mach number ranging from 2 to 3, accompanied by obvious gradients of steady density, pressure, and temperature. However, the terrestrial leak from 2 atm to 1 atm forms subsonic jet flow with gradually varying gradients of density, pressure, and temperature. Thirdly, obvious reflections of pressure perturbations at the surface, with the mean free path of air molecule being 0.6 mm, can be found and form cavity-like acoustic resonance. Such resonant mechanism contributes to harmonic acoustic properties of the vacuum jet noises besides the broadband turbulent mixing noises.
Highlights
On April 19, 1971, the world’s first space station, Salyut 1, was successfully launched into orbit, marking the arrival of space age
The realizable k-ε model is adopted in this paper to numerically simulate the aerodynamic
(1) On jet thewith spacea station, the leakofgas will expand into outer spacecore rapidly and form25 a supersonic
Summary
On April 19, 1971, the world’s first space station, Salyut 1, was successfully launched into orbit, marking the arrival of space age. Because the leak jet enters the vacuum directly, the acoustic emission signal propagating backwards into the pressure vessels is very weak. Reusser et al [9] studied propagation and reflection mechanisms of low-order Lamb waves in stiffener components and constructed a generalized impedance model, which had good agreement with numerical simulation results. Abedi’s group [21,22] conducted a leak detection test on the ISS and the measured spectrum showed obvious harmonic wave series, which cannot be explained by screen tone theory in supersonic jet noise. This paper concentrates on the numerical simulation of a specific leak condition, preliminarily revealing the aerodynamic properties and mechanism of the noise propagation in vacuum environment.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
