{"id":215805,"date":"2026-04-02T09:30:16","date_gmt":"2026-04-02T09:30:16","guid":{"rendered":"https:\/\/www.newsbeep.com\/us-fl\/215805\/"},"modified":"2026-04-02T09:30:16","modified_gmt":"2026-04-02T09:30:16","slug":"famu-fsu-college-of-engineering-researchers-develop-new-model-for-predicting-noise-feedback-loops-from-supersonic-jets-2","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us-fl\/215805\/","title":{"rendered":"FAMU-FSU College of Engineering Researchers Develop New Model for Predicting Noise Feedback Loops From Supersonic Jets"},"content":{"rendered":"

\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tThe research could help develop methods for reducing intense noise that threatens aircraft and ground crews<\/p>\n

Newswise \u2014 Researchers from the FAMU-FSU College of Engineering<\/a> and the Florida Center for Advanced Aero-Propulsion<\/a>, or FCAAP, are helping to solve a safety challenge in military aviation: the extreme noise generated by supersonic jets during takeoff and landing.<\/p>\n

The research, published in the Journal of Fluid Mechanics<\/a>, demonstrates a new model for understanding how supersonic jets of air collide with the ground or other structures to create a resonant feedback loop that produces extreme noise that can reach dangerous volume levels.<\/p>\n

The team examined jets like those found in a type of aircraft known as Short Takeoff and Vertical Landing jets, or STOVL. The ability to operate without a traditional runway gives these aircraft, such as the F-35B Lightning II, critical tactical advantages.<\/p>\n

But as they descend toward the ground, their exhaust plumes interact with landing surfaces and generate intense noise, often exceeding 140 decibels, posing serious dangers to both aircraft structure and nearby personnel.<\/p>\n

\u201cOnly a tiny fraction of the jet\u2019s energy is transformed into sound, but this small fraction has a major impact,\u201d said Farrukh S. Alvi, professor in the Department of Mechanical and Aerospace Engineering<\/a> and former founding director of the Institute for Strategic Partnerships, Innovation, Research, and Education, or InSPIRE, and founding director of FCAAP. \u201cThe intense noise produced by jet engines can cause structural damage to the aircraft and damage the hearing of personnel on the ground. We are trying to understand the physics behind these supersonic jets and the noise they produce so that we can develop tools that can reduce their impacts. In fact, we have already had some success in developing techniques that can reduce jet noise.\u201d<\/p>\n

Why it matters<\/p>\n

When the high-speed air coming from jet engines mixes with the ambient air, it creates large-scale disturbances that hit the ground, producing strong sound waves that propagate back toward the jet engine. This establishes a repeating, back\u2011and\u2011forth interaction and creates resonance, an example of a feedback loop, causing loud and repeating noise. For aircraft, these resonant vibrations accelerate structural fatigue and can generate hazardous low-pressure zones that can pull the aircraft toward the ground.<\/p>\n

For crewmembers on the ground, sustained exposure to sound levels over 140 decibels can cause permanent hearing damage, even when wearing protective equipment. At peak intensities, extreme acoustic pressure can even cause organ damage.<\/p>\n

\u00a0<\/p>\n

https:\/\/news.fsu.edu\/wp-content\/uploads\/2026\/03\/Animation_02.mp4<\/a><\/p>\n

An animation showing an aircraft using supersonic jets for a vertical landing. As it descends toward the ground, exhaust plumes interact with landing surfaces to generate intense noise, often exceeding 140 decibels, posing serious dangers to both aircraft structure and nearby personnel. (Courtesy of Myungjun Song)<\/p>\n

\u00a0<\/p>\n

\u00a0A new approach to modeling jet resonance<\/p>\n

The research team tested a supersonic, Mach 1.5 jet \u2014 1.5 times the speed of sound \u2014 and adjusted nozzle pressure and the jet\u2019s distance from the ground to simulate take-off\/landing and make a range of measurements.<\/p>\n

To see the airflow, they used a high\u2011speed camera and a specialized visualization technique called schlieren imaging that allowed them to \u2018see\u2019 the jet flow \u2014 including its large-scale disturbances and the sound waves generated in real time. At the same time, a highly sensitive microphone also recorded the sound produced by the jet.<\/p>\n

When the jet is loud, the jet flow and the sound waves repeat at a regular rhythm, which is a characteristic of a resonant cycle. By matching images to a specific point in the cycle, the researchers developed a clear picture of the airflow and measured how fast large-scale disturbances in air moved and how sound waves traveled back toward the nozzle.<\/p>\n

The researchers found that for many cases, the pitch \u2014 how the human brain perceives the frequency of sound waves \u2014 of the noise was primarily governed by acoustic standing waves, which appear stationary in space between the body of the plane and the ground. The findings reveal that the pitch is not primarily governed by disturbance velocity, thereby offering another perspective on the existing understanding of the resonance feedback. They also found that slower disturbances tend to be larger, consequently creating louder noise.<\/p>\n

\u201cThat was surprising,\u201d said postdoctoral researcher Myungjun Song, the study\u2019s lead author. \u201cWe found that these acoustic standing waves are much more important in determining the pitch, while the size and speed of the disturbances decide the level or \u2018loudness\u2019 of the noise produced.\u201d<\/p>\n

The discovery offered the research team an insight. Because the disturbance speed has little effect on pitch, information about acoustic standing waves would be enough to predict the noise pitch.<\/p>\n

The new model enables engineers to predict noise frequencies more easily during aircraft and landing pad design, a critical step toward protecting both aircraft structures and personnel from acoustic trauma.<\/p>\n

World-class research facilities drive discovery<\/p>\n

The experiments were conducted at FCAAP\u2019s specialized research facilities, designed for advanced high-speed aerodynamic studies at the FAMU-FSU College of Engineering.<\/p>\n

Researchers used the FCAAP\u2019s STOVL facility, which offers cutting-edge flow diagnostic capabilities, and the hot jet facility, which can generate high-temperature, high-speed airflow in an anechoic chamber to allow for highly accurate acoustic measurements under realistic jet conditions.<\/p>\n

\u201cWhile jet propulsion is an important focus of our work, our research is not limited to it,\u201d Alvi said. \u201cThe university and the college, through FCAAP, operates a polysonic wind tunnel that simulates supersonic flows up to Mach 6 \u2014 supersonic to hypersonic conditions. We also use our anechoic wind tunnel and subsonic wind tunnels for numerous other aerospace related research projects. Together, these facilities and the expertise of our researchers create a one-of-a-kind ecosystem for conducting leading-edge research in aerospace and aviation.\u201d<\/p>\n

An associated initiative, InSPIRE is an FSU-led effort to establish a new aerospace and advanced manufacturing hub in Bay County, Florida. The program builds on FCAAP\u2019s foundation to develop complementary facilities for larger hypersonic wind tunnels that can handle a wider range of conditions for applied, industry-relevant research.<\/p>\n

\u201cIn partnership with industry, InSPIRE is also integrating advanced manufacturing capabilities that will allow much more efficient test and evaluation and assist our industry partners to innovate manufacturing processes in a realistic factory-modeled setting,\u201d said Alvi, the former director of InSPIRE. \u201cWorking with industry partners allows our researchers to use their expertise to solve the pressing and difficult problems that are directly relevant for industry.\u201d<\/p>\n

Research team and support<\/p>\n

The project was a collaborative effort involving Song, the study\u2019s lead author; Alvi; and graduate student Serdar Se\u00e7kin.<\/p>\n

Funding was provided by the Office of Naval Research, with additional support from the National Science Foundation, the Air Force Office of Scientific Research, FCAAP, the FAMU-FSU College of Engineering and the Don Fuqua Eminent Scholar Fund.<\/p>\n

\u00a0<\/p>\n

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