Ray Tracing: A Saving Grace for the Aerospace Industry?
Virtual Prototyping predicts exterior noise levels for launchpad acousticsWednesday, June 16, 2021
By Dr. Bryce Gardner
Avoiding a space catastrophe
We have liftoff! What wonderful and exciting words to hear for anyone in the space industry – and even for those watching from the sidelines. What’s not so great for spacecraft engineers and manufacturers to hear? How damaging the extreme acoustic environment can be on launch vehicles and their payloads. Surviving this acoustic load is critical to the proper functioning of the vehicle and payloads. Therefore, predicting the acoustic load is essential to providing necessary input to determine the structural vibration and sound transmission through the vehicle structure – or else the results could be catastrophic.
Although predicting exterior noise levels when dealing with structures like the launch pad and launch vehicle is critical, these are also too large to model with conventional deterministic methods and become computationally expensive. And what about the environment surrounding the launch pad? Minimizing exterior noise also plays a large part in operator safety and comfort, contributing to greater overall efficiency.
The impact that launch acoustics, large structures and noise pollution have on space exploration
As mentioned, launch acoustics are the most damaging loads that the rocket and everything inside of it experience. It can be so severe that the noise level can vibrate and shake apart key components of the rocket, the guidance system or the satellites inside, which can cause a catastrophic failure. During lift-off, the exhaust plume from the engines generates a considerable amount of noise, which induces high vibration loads – and happens to be quite complex and difficult to characterize. Because of this, it becomes essential for engineers to:
- calculate the exterior loads accurately
- run through the standard simulation process using ESI’s industry-standard coupled BEM and SEA solutions
And, for a moment, let’s stop to think about these structures we are dealing with – structures that can reach up to 300 feet tall. In cases like these, everything becomes exacerbated, including the modeling of the structures. For many years, it was common practice for industry leaders to turn to deterministic methods for noise prediction. Because of the sheer size of these structures, this becomes impractical, as models become larger, working with them is more challenging, time-consuming and costly.
Today, another major challenge the space industry must contend with is exterior noise. Considering the noise is so loud – about 180 decibels – that it can damage parts of the spacecraft itself, imagine the damage it could do to the structures and the people in the vicinity. Teams must be cognizant of the acoustics around the launch vehicle, for example in the control tower and the surrounding area and work to minimize the noise.
Ray Tracing – quick and accurate analysis of the acoustic environment
ESI’s Ray Tracing capabilities extension combined with its existing industry-standard vibroacoustic offering provides engineers an integrated, all-in-one vibroacoustic solution. Engineers can, with the full details of the launch pad, get an accurate load to place on the launch vehicle in order to calculate the structural qualification and dynamics. This ray-based technique provides a mesh and frequency-independent method and, subsequently, an efficient alternative for a quick and accurate solution. With ray tracing and its ability to push to high frequencies for a large model, one can survey and predict the noise around the entire launch pad area in addition to getting the acoustic levels on the fairing and the payload, which is critical to the space industry. This combined approach offers a quick and accurate solution for predicting the acoustic environment in general as well as the dynamic response of the structure and interior cavities in the presence of large and complex shaped geometry.
For more information watch our webinar on Structural Integrity and Acoustic Qualification of Space Hardware
Learn more about ESI’s Vibroacoustic Solutions
Dr. Bryce Gardner
Lead Acoustic Scientist
Dr. Bryce Gardner is the Lead Acoustic Scientist at ESI Group working on the VA One simulation solution team. He has been solving structural acoustics problems for the past thirty-some years, both in the aerospace and automotive industries. He has a PhD from Purdue University and serves on the NASA Engineering & Safety Center Loads & Dynamics Technical Discipline Team.