Noise and Thermal Management of Naval Systems - Aircraft Carrier Noise Measurement and Mitigation
“I am a more applications-based person, says Ted. “As compared to many other graduate students, I feel no one has been presented with such a hands-on application of research. It has been a huge draw for me. I don’t think there are many projects that provide such a great opportunity as NEEC does.”
NEEC Student Ted Worden.
The project poster presented at the 2012 NEEC Summer Meeting..
Lockheed Martin's F-35B. All rights reserved by Lockheed Martin.
It’s no secret that since the beginning of naval architecture countless hours of research and investigation have been invested to understand how water affects the design and construction of a ship. But as time and technology change, new influences are impacting the ship design process – this time from above. Consider the advent of aircraft on Navy ships, in particular, the new F-35B Joint Strike Fighter (a vertical launch aircraft), and you can begin to see how new forces can significantly impact the field.
This month we head to Florida to check in on the progress being made on a new NEEC project involving the Florida A&M University-Florida State University (FAMU-FSU) College of Engineering. This NEEC team has set out to provide the Navy with a better understanding of impinging jet noise and its potential impact on ships, as well as methods of suppressing this noise.
“It’s an interesting area of research sometimes being overlooked.” Says Professor Chiang Shih, the NEEC Principal Investigator on the project who is Professor of Mechanical Engineering as well as the Director of the Aero-propulsion, Mechatronics, and Energy Center, at Florida State University.
You may think it would be a relatively straight forward problem to research – but not so fast. As research dollars and budgets tighten, the question of who is responsible for understanding the strain and impact of aircraft-generated noise and heat on ships and carrier decks becomes more complicated. “We believe this is a unique project for NAVSEA since the below deck noise/vibration problem is inherently a critical ship design issue. However, relatively little attention has been focused on the above-deck noise since it seems to be considered more of a NAVAIR-related problem,” says Professor Shih. “With our expertise and facilities, we can play a major role in interfacing these two perspectives and we will work closely with the NSWC-Carderock Signatures Department to identify relevant parameters for the testing to further identify practical noise mitigation technologies to integrate into future flight deck design.”
The NEEC team at Florida State University is uniquely poised to help as they have cutting-edge facilities for the study of both impinging and free jet flow. At Florida State’s new Aero-propulsion, Mechatronics, and Energy Center, the High-Temperature Supersonic Jet (HotJet) and Short Take-off and Vertical Landing (STOVL) facilities are capable of generating the high-pressure, high-temperature flows necessary for the accurate simulation of jet engine exhaust. These jets can be produced at temperatures of up to 2200 °F and speeds beyond Mach 2.5.
“These new aircraft create noise and vibration affecting the surrounding structures and personnel, but we do not really have a good understanding of the magnitude of these effects on the deck structure of Navy ships,” says Ted Worden, a NEEC student who works with Professor Shih on the project.
In case you were wondering, this next generation of vertical take-off and landing aircraft, such as the Navy’s F-35B, utilize nozzles and lifting fans that produce vertical air jets to generate lifting force at low or zero forward airspeed. These hot, high-speed jets generate significant pressure and temperature loads on the tarmac or aircraft carrier deck. Close to the ground, the induced flow around the aircraft also produces lift loss and may result in hot gas ingestion in the engine air intakes, potentially producing combustion instabilities and thrust loss. In addition to these effects, it has been found that the jets impinging on the ground generate large-scale instabilities leading to significant unsteady pressure and acoustic loads on the aircraft, ground structures, and surrounding personnel.
Noise from most modern tactical aircraft is dominated by the jet noise produced from the exhaust of very high-speed (supersonic in most cases) gases from the jet engines. Noise levels in the vicinities of these aircraft are extremely high - often as high as 150 dB or more which is louder than a rock concert. When operating at STOVL mode or interacting with the jet blast deflector, the situation gets worse as the high speed jet stream impinges on neighboring surfaces generating even higher-level discrete tones and sound pressure levels. This creates a number of serious problems:
it poses considerable risk to the health and safety of the personnel on aircraft carrier decks;
the high noise levels may also impact the safety, structural integrity and operational lifetime of aircraft and nearby structures; and
the below deck noise transmission can adversely affect operational conditions for personnel who live and work in the gallery deck.
“STOVL and VTOL aircraft are the next generation of high performance aircraft and there is plenty of room for improvement regarding the safety of personnel, structures and cost issues involved,” points out Ted.
Ted is currently designing and executing a set of experiments on impinging jet studies extended to higher temperature applications. When asked about the work on this project and his connection to NEEC, Ted added, “I feel we are unique in the NEEC realm because we are bridging the gap between air and sea.”
And this project is truly unique in that regard. Of the 22 active NEEC projects, this is the only project that takes into consideration the impact of aircraft on Navy ships. “We feel this project is something the Navy was very interested in,” adds Professor David Singer - NEEC Co-Director who is key in the project selection process. “We want to provide educational opportunities and projects that address a wide spectrum of naval concerns and this project fits.” Especially when you consider the recent discussions in the news about the Air-Sea Battle concept (see CNO Admiral Jonathan W. Greenert talk given May 16th at Brookings) you can begin to see how aircraft are an essential component to what the Navy is about.
This NEEC project was newly awarded for the 2012-2013 project phase but during its short existence it has provided a great opportunity for those involved. “I am a more applications-based person, says Ted. “As compared to many other graduate students, I feel no one has been presented with such a hands-on application of research. It has been a huge draw for me. I don’t think there are many projects that provide such a great opportunity as NEEC does.”
From a Navy perspective, this project addresses an area of new concern as the Navy looks at how technology from above impacts its ships. “Using the NEEC we have established a connection to NAVSEA to do something meaningful,” added Professor Shih. Not only will this project provide a level of research which will benefit the Navy, it will engage and educate students in the complex issues the Navy will face as its technology and missions change.
FAMU-FSU students currently engaged in NEEC:
Ted Worden - Graduate Student and Research Assistant, Mechanical Engineering
John Edgar - Senior, Mechanical Engineering
Professor Shih and his team collaborate with Dr. Paul Shang from the Naval Surface Warfare Center (NSWC) Carderock Division.
We encourage you to stay connected to this project and check back to the GoNEEC.org website for updates on the progress Professor Shih is making on this part of the project.
For questions or comments regarding this story, please contact Keith Bretzius, NEEC Communication Manager at kbretzius@GoNEEC.org or by phone at (734) 763-7958.
- Advanced Aero Propulsion Laboratory - Impinging Jets
- Advanced Aero Propulsion Laboratory - High Temperature Supersonic Jet
- Aero-Propulsion, Mechatronics and Energy Building (AME)
- Air-Sea Battle Doctrine: A Discussion with the Chief of Staff of the Air Force and Chief of Naval Operations
- F-35B - Taking STOVL to a New Level
- Naval Engineering Debacle?
- Navy, Marines Bet Big on Carrier for Troubled Stealth Jets