Sonic Boom Minimization in Supersonic Jet Propulsion: A Technical Playbook

Sonic boom minimization in supersonic jet propulsion is a critical area of research, with numerous studies and efforts dedicated to understanding and reducing the impact of sonic booms on the ground. The sonic boom is a thunder-like noise heard on the ground when an aircraft flies overhead faster than the speed of sound, caused by the coalescence of shock waves generated by the aircraft.

Aircraft Design for Sonic Boom Minimization

One of the key aspects of sonic boom minimization is the design of the aircraft itself. A design tool incorporating classical sonic boom theory, computational fluid dynamics, and a multi-objective genetic algorithm was developed for low-boom optimization in supersonic aircraft. This framework allows for system-level integration of several key enabling analysis tools and automation methods to optimize supersonic aircraft design for low-boom characteristics.

Shaped Sonic Boom Signatures

NASA’s HSR Program identified three key requirements for overland supersonic flight, including establishing the criteria for an acceptable “shaped” sonic boom. However, it is important to note that all existing sonic boom signatures are sawtoothed (N waves), as current signature prediction codes work well for N-wave aircraft but have not been demonstrated for shaped signature aircraft in real-world atmospheric conditions.

Atmospheric Turbulence Effects

Atmospheric turbulence in the lower layers of the atmosphere can produce large changes in the overpressure or intensity of N-wave sonic boom signatures. Future research programs should consider investigating advanced concepts for reducing wave drag or sonic boom amplitude, such as active flow control, virtual shaping, and energy addition in various forms.

Sonic Boom Data and Measurement

sonic boom minimization in supersonic jet propulsion

A study by NASA’s HSR Program revealed that nearly 50 years of flight data and experience with sonic booms exist, covering some 20 different supersonic aircraft, including the Concorde and the space shuttle, with over 1,500 flights having produced some 15,000 measured signatures. However, these aircraft were so-called N-wave designs, meaning that sonic boom minimization was not considered in their basic design.

Technical Specifications for Sonic Boom Minimization

In terms of technical specifications for sonic boom minimization, a new framework was presented for shape optimization using analytical shape functions and high-fidelity computational fluid dynamics (CFD) via Cart3D. This framework allows for system-level integration of several key enabling analysis tools and automation methods to optimize supersonic aircraft design for low-boom characteristics.

Boom Minimization Case Study

For a boom minimization case study, perceived loudness and overpressure levels were used as measures of low-boom characteristics, and a design space exploration was carried out to assess the key parameters and constraints driving the design. The design problem, analysis processes, and optimization framework were described, along with a case study to demonstrate a subset of the framework capabilities.

Challenges and Future Research

In summary, sonic boom minimization in supersonic jet propulsion is a complex and challenging area of research, requiring advanced design tools, computational fluid dynamics, and a deep understanding of atmospheric conditions and aircraft aerodynamics. While significant progress has been made in this field, there is still much work to be done to establish a credible scientific foundation for designing supersonic aircraft with low sonic booms and to develop improved analytical tools.

Some key challenges and areas for future research include:

  1. Developing advanced design tools and optimization frameworks for low-boom supersonic aircraft
  2. Improving computational fluid dynamics (CFD) models and simulations to accurately predict shaped sonic boom signatures
  3. Investigating the effects of atmospheric turbulence and other environmental factors on sonic boom propagation
  4. Exploring innovative concepts for reducing wave drag and sonic boom amplitude, such as active flow control and energy addition
  5. Conducting more extensive flight testing and data collection to validate sonic boom prediction models and design approaches

By addressing these challenges and continuing to push the boundaries of sonic boom minimization research, the aerospace industry can work towards the goal of enabling a new generation of supersonic aircraft that can operate with minimal impact on the ground.

References:
Supersonic aircraft optimization for minimizing drag and sonic boom
Sonic Boom Prediction and Minimization | Encyclopedia MDPI
Chapter: 3. New Opportunities for Research on Critical Supersonic Technologies
Boom Minimization Framework for Supersonic Aircraft Using CFD Analysis
Supersonic Technologies – NASA
Sonic Boom Minimization Techniques for Supersonic Aircraft
The Science of Sonic Booms and Their Minimization