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Predict Space Structure Integrity with Aero-Vibro-Acoustic (AVA) Simulation
Why Engineers Use VA One to Ensure Structural Integrity of Spacecrafts Early and Accurately
As space exploration pushes boundaries, engineers face unique challenges ensuring spacecraft can endure intense conditions, particularly during launch, ascent, and descent. One of the most complex issues is aero vibroacoustics (AVA), specifically during the rocket’s ascent phase, where turbulent airflows around the rocket excite the structure. These excitations can compromise sensitive equipment and payload integrity due to high sound pressure levels and vibrations.
To help engineers understand and address these phenomena, advanced simulation tools like VA One provide the precision and comprehensive analysis necessary to tackle AVA complexities in space. In this blog article, we'll explore the challenges of AVA in space and why VA One is the industry-preferred solution for vibroacoustic simulation.
What Is Aero Vibroacoustics (AVA) in Space Engineering?
Aero vibroacoustics studies how airflows induce vibrations and acoustic responses in structures. In space missions, AVA is particularly relevant during a rocket's ascent phase, especially when the rocket enters transonic conditions. At this stage, turbulent boundary layers (TBL) induce vibrations in the rocket’s fairing, which houses sensitive equipment and payloads. These vibrations and resulting high sound pressure levels propagate through the structure, creating acoustic waves that could jeopardize both payload performance and the electronic components inside the fairing.
What Methods Are Used in AVA Simulation?
The AVA simulation process involves calculating aerodynamic pressure fluctuations using either computational fluid dynamics (CFD) data or test data. There are three primary loading methodologies for vibroacoustic analysis, depending on the frequency range:
- Fluctuating Surface Pressure (FSP) for low-frequency analysis: This method converts Computational Fluid Dynamics (CFD) results into the frequency domain and applies them to a finite element model (FEM) of the structure and cavity. This helps predict how the structure will respond to the pressure fluctuations during ascent.
- General Surface Pressure (GSP) for high-frequency analysis: This method uses wave-number transformation to analyze pressure fluctuations and their impact on the structure. It converts CFD data into loads suitable for the Statistical Energy Analysis (SEA) method.
- Turbulent Boundary Layer (TBL): This method uses the chaotic, high-energy fluid regions along the spacecraft’s surface to model the loads. It represents the interaction between turbulent airflow and the structure, approximating the load applied by turbulent flow on the surface (e.g., a fairing or vehicle body).
Each method focuses on assessing how aerodynamic loads affect structural vibrations and noise propagation within a cavity, such as a rocket fairing or vehicle cabin. The choice between TBL, FSP, and GSP depends on the frequency range and the complexity of the simulation.
What are the Challenges of AVA Analysis in Aerospace Engineering?
Engineers face several critical challenges when analyzing aero-vibro-acoustics in space missions. These challenges include:
- Data Accuracy: One of the main challenges in AVA simulation is ensuring the accuracy of the CFD results before they are used in vibroacoustic analysis. In aerospace, this ensures that the loads—comprising both convective and acoustic components—are correctly applied to the structural model.
- Wide Frequency Range Requirements: Spacecraft experience vibroacoustic loadings under a broad range of frequencies. During lift-off, low-frequency vibrations combine with high-frequency acoustic loading, putting strain on the spacecraft structure. Engineers need simulation tools that can model this full range, from the lowest to the highest frequencies, to ensure designs can withstand all potential loads.
- Complex Acoustic Phenomena: Understanding how acoustic energy travels through structures is crucial in AVA. Engineers face the challenge of determining how vibrations from turbulent airflows interact with structural components. This requires sophisticated tools to separate and analyze the acoustic components from the other dynamic forces present during flight.
- Data Complexity and Modeling: To simulate these complex interactions, engineers work with large amounts of data related to pressure time histories of turbulent airflows. High-fidelity modeling is required to provide accurate predictions of how the structure will behave under different conditions, but this can also lead to increased computational costs if the simulation tool is not optimized.
How Can Engineers Use VA One for Ascent Phase Modeling?
Pre-test aero-vibro-acoustic analysis is essential for ensuring the reliability and performance of spacecraft. Using ESI’s OpenFOAM, an open-source CFD toolbox, alongside VA One provides a comprehensive solution for this process. OpenFOAM generates pressure time histories on the surfaces, which are then integrated into VA One for advanced simulations. This integration reduces costs and streamlines the workflow by having both CFD and acoustic analysis from a single provider.
To model the ascent phase of a spacecraft, users can apply the loads experienced during ascent using three different methods: Turbulent Boundary Layer (TBL), Finite Structural Potential (FSP), or General Surface Pressure (GSP). These loads can be derived from either measured data (actual flow data collected during tests) or simulated data (flow data generated through simulations).
The wave-number transformation is important because it allows us to apply loads to the structure more accurately, without relying on simplified models like traditional TBL. By using the wave-number frequency spectrum directly, we can avoid assumptions and improve the accuracy of the results, especially when modeling how flow excites a structure and generates noise or convective energyvibrations.
Dr. Alexis CastelTechnical Expert, ESI Group, a part of Keysight Technologies
The Value of Using VA One for Aero Vibro Acoustic Assessment in the Space Industry
VA One is a flexible, powerful tool designed to solve complex aero-vibro-acoustic problems. Here’s why it’s the preferred solution for tackling AVA challenges in space missions.
When it comes to pre-hardware test validation, ESI's VA One stands as the trusted, legacy software solution for space engineers worldwide.
- Comprehensive Frequency Range Coverage: VA One offers a full frequency approach that combines finite element (FE) models, boundary element, and statistical energy analysis methods. This enables detailed low-frequency analysis while efficiently handling high-frequency behavior, ensuring comprehensive vibroacoustic spectrum coverage.
- Integration with CFD: VA One integrates seamlessly with CFD tools like OpenFOAM and others, enabling fluid-structure interaction simulation and highly accurate uncoupled aero-vibro-acoustic analysis.
- Advanced Acoustic and Vibrational Analysis: VA One’s wave-number transformation techniques allow for precise analysis of airflow-induced vibrations, enabling engineers to avoid oversimplified models and capture critical details.
- Efficient High-frequency Simulation: VA One’s SEA capabilities enable efficient high-frequency simulation, saving time and resources while maintaining accuracy—crucial for space missions.
Tools within ESI's VA One software help validate these CFD results, ensuring precise load application for both SEA and FEM. This combination of OpenFOAM for CFD calculations and VA One enables engineers to achieve accurate, reliable results, trusted by engineering review boards worldwide.
Dr. Alexis CastelTechnical Expert, ESI Group, a part of Keysight Technologies
In a Nutshell: Need High Result Accuracy of AVA Simulations? Choose VA One.
Aero-vibro-acoustics presents significant challenges for engineers, especially as spacecraft are exposed to extreme aerodynamic forces during ascent and transonic flight. Accurate AVA simulation across a broad frequency range is essential for spacecraft integrity and mission success. VA One stands out as the preferred aero-vibro-acoustic simulation tool due to its comprehensive frequency analysis, CFD integration, advanced modeling techniques, and high-frequency simulation efficiency. These features provide engineers the confidence to tackle AVA challenges early in the design cycle and ensure rockets withstand immense ascent and transonic forces.
Calling all Acoustic Engineers in the Space Industry: Join Our Technical Webinar on Low Frequency Acoustic Analysis!
Don’t miss the opportunity to hear directly from Alexis, a leading technical expert in Space acoustics engineering, as he delves into the intricacies of assessing structural integrity using VA One. In this blog, we’ve underscored the critical role of accurate Aero-Vibro-Acoustic (AVA) simulations in safeguarding spacecraft performance in the ascent phase. Now, take your expertise further by joining our webinar, where Alexis will break down Low Frequency Acoustic Analysis with FEM-BEM in VA One.
Author
Massimiliano Calloni
Sr. Vibro-Acoustic Product Marketing Manager
Dott. Ing. Massimiliano Calloni is the Senior Product Marketing Manager for ESI Group, where he plays a pivotal role in shaping the future of vibro-acoustic simulation technology. With a Master’s degree in Aerospace Engineering from the prestigious Politecnico di Milano, Massimiliano brings over two decades of deep expertise in Noise & Vibration. His career includes six years at AgustaWestland Helicopters, where he excelled as a consultant in both testing and simulation. Today, he leverages his extensive technical knowledge and marketing acumen to drive the global success of ESI’s VA One software, supporting strategic initiatives worldwide.
Category: Aerospace