SBIR-STTR Award

The absence of a comprehensive, integrated aerodynamic/aero-acoustic modeling and analysis framework represents an impediment to achieving significant noise reduction within constraints imposed by the engine cycle, realistic geometry, and airframe. We close the gap by developing a suite of advanced, high fidelity nozzle performance and jet noise-based tools integrated into a unified software package with validation cases and applicability assessments. The flow field software will be based on TTC Technologies, Inc. multi-disciplinary high-order CFD tool, AEROFLO, which predicts temporal and spatial flow fields at all speeds (subsonic, transonic, supersonic, and hypersonic). The tools, ranging from RANS to LES, will be installed as modules interfaced with a comprehensive set of aeroacoustic source modules populated with fundamental physics-based aeroacoustic and semi-empirical models, to allow a range of prediction methods via pull-down 0x9D menus. A large-scale noise model based on a RANS/PSE approach developed by UTRC and Caltech will also be implemented. The simulation codes will be rigorously validated using UTRC acquired data with limitations documented in terms of accuracy, robustness, sensitivity, turnaround time plus recommendations for improvements. The tool will provide a comprehensive approach to the design and development of nozzle components that attenuate exhaust jet noise.

Benefit:
The proposed suite of advanced, high fidelity nozzle performance and jet noise-based tools integrated into a unified software package represents an innovative predictive tool which engine and aircraft manufacturers do not currently have. The product will support a broader objective of developing new concepts for jet noise suppression based on modification and control of large-scale turbulence which dominates tactical aircraft jet exhaust peak noise levels. The Department of Defense, NASA, and other government agencies that use aerospace technology will benefit significantly from this product, since the unified framework for this fast and accurate methodology will be capable of dealing with realistic nozzle geometries at subsonic and supersonic nozzle exhaust velocities. The tool will enable timely screening of new jet engine concepts early in the design process. The proposed product could be bundled into a software module that will interface with government and commercial computational fluid dynamics (CFD) codes in order to obtain jet noise prediction data. It will also will be available to the Navy as a standalone tool, and add significant value to existing CFD codes, thereby making the tool attractive to CFD vendors. The product is expected to lead to consulting and code enhancement activity over the long term (Foluso: not sure if code enhancement is a benefit to governmentit s a benefit to you/TTC which we discussed), thus increasing the profitability of numerous consulting firms that use CFD technology in their business.

Keywords:
noise models, noise models, screech, broadband shock noise, large-scale noise, parabolized stability equations, fine-scale noise, wave-packet models, Jet noise,

The development of optimal engine exhaust noise reduction technology for tactical aircraft continues to rely heavily on laboratory-scale testing due to the absence of appropriate modeling and analysis capability. Thus, concept identification relies largely on engineering intuition, ad hoc reasoning, and exhaustive parametric testing. Another obstacle to the development of exhaust noise technology is the absence of integrated tools for simultaneous assessment of aero-acoustic and aerodynamic performance. The research proposed by TTC Technologies, Inc., (TTC) is to develop and demonstrate innovative methodologies for simultaneous nozzle acoustic and aerodynamic design applicable to supersonic jet exhaust noise reduction in tactical aircraft. Methodologies will be demonstrated via concept design/analysis, followed by experimental validation at model scale. Improved computational efficiency and turn-around will be achieved by developing more robust and efficient numerical procedures. The methodologies will be integrated into a design procedure and applied to nozzle geometries being developed in ongoing Department of Defense noise reduction programs. The proposed effort leverages existing advanced TTC tools, as well as novel jet noise modeling and experimental diagnostic capabilities currently being developed under a NAVAIR-funded effort involving TTC, United Technologies Research Center (UTRC) and California Institute of Technology (CIT).

Benefit:
The outcome of the innovative research proposed by TTC Technologies, Inc., (TTC) will significantly contribute to the development of engine exhaust noise reduction technology for supersonic tactical aircraft. Todays heavy reliance on laboratory-scale testing, engineering intuition, ad hoc reasoning, and exhaustive parametric testing for concept identification will be greatly alleviated. The proposed approach provides an inexpensive way to rapidly assess whether proposed designs will be effective, and determines whether such designs are optimal. Thus, an impediment toward achieving significant noise reduction for tactical aircraft will be removed. Furthermore, the proposed tool will allow simultaneous assessment of aero-acoustic and aerodynamic performance, allowing for non-acoustic design objectives such as nozzle thrust, aircraft stability, and IR signature to be considered early in the noise concept design process. This prevents designs with unnecessarily compromised aerodynamic performance and point designs, 0x9D which neglect the overall mission envelope. The commercial value of the predictive tool proposed by TTC is evident. Both government and non-government entities will find the proposed software to be very valuable. The Department of Defense (DOD), Department of Energy (DOE), and the National Aeronautics and Space Administration (NASA) will be able to utilize the tool for their various projects on engine concepts. The speedup and fast turnaround from CFD analysis with the module will enable parametric testing of many design configurations in a timely manner. The innovative features in the proposed tool will make the product directly applicable to DARPA-funded initiatives on new space vehicle designs. The expected accuracy and robustness of the procedure also assures the design data generated with the code. The ultimate benefits are community-friendly engines and prevention of structural problems associated with excessive jet noise. The commercialization potential of the predictive tool proposed by TTC is also great from the standpoint of the number and breadth of non-governmental organizations and industries that currently look to the CFD technology for a competitive advantage. Vendors of computational fluid dynamic (CFD) software currently do not have the capabilities for fast and accurate prediction of supersonic jet noise. The significant savings in time and money that is inherent in the proposed procedure will motivate these companies to acquire it for competitive noise prediction. Engine companies will also need TTCs compelling technology. These companies have in-house CFD codes, but the capability to accurately simulate supersonic jet noise problems for screening advanced concepts is either non-existent or very primitive. The fast turnaround that the proposed software promises will make these companies acquire the product for timely screening of their design concepts.

Keywords:
Supersonic jet noise, Acoustic projection method, noise reduction, wave packets, Reynolds-averaged Navier-Stokes (RANS), Chevron nozzle, Parabolized Stability Equations (PSE)