Evaluation of the National Aerospace Initiative (2004) / Chapter Skim
Currently Skimming:
2 Hypersonic Flight
2 Hypersonic Flight
Pages 24-52
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 24... ...
On the other hand, scramjet technology has matured significantly over the past decade or so, and the flight-testing of scramjet engines is imminent. Computational methods such as computational fluid dynamics (CFD)
|
From page 25... ...
, especially flight demonstration programs aimed at maturing air-breathing hypersonics technologies to the point where decisions can be made about the development of large-scale Global Strike/ISR aircraft and air-breathing space access vehicles. A realistic budget must be projected consistent with answering the critical technology challenges, and existing programs should be more closely aligned, taking advantage of the synergistic potential championed by NAI, so they can provide critical hypersonics technologies to the nation.
|
From page 26... ...
It is not clear that the process, as used by NAI, was effective in defining a comprehensive and compelling technology development program, from fundamental research to flight demonstration, that would sufficiently mature all technologies critical to operational hypersonic flight. Particularly noteworthy is the low level of fundamental research (6.1 and 6.2)
|
From page 27... ...
SOURCE: Sega, 2003b. opment, ground testing, and flight demonstration plans required to mature enabling technologies to the point where they can be applied to operational hypersonic flight.
|
From page 28... ...
The four critical technologies are these: · Air-breathing propulsion and flight test, · Materials, thermal protection systems (TPSs) , and structures, · Integrated vehicle design and multidisciplinary optimization, and · Integrated ground testing and numerical simulation/analysis.
|
From page 29... ...
programs and NASA's X-43C program. With the HyTech program, the Air Force is developing and ground testing a hydrocarbon scramjet engine.
|
From page 30... ...
For example, development and incorporation of an engine control system that prevents engine flameout or inlet unstart and demonstration on a single-engine module in flight might mitigate the risk of multiengine operation sufficiently to permit the use of multiple engines in a later reusable flight demonstration. The committee notes that canceling or restructuring existing programs can be politically and contractually sensitive.
|
From page 31... ...
indicated that the technology readiness of the materials for the same vehicle and propulsion system was much lower, though the rating system used by the Air Force was not numerical and therefore difficult to correlate. Both NASA and the Air Force made the point that significant effort will be needed to develop materials for high heat flux applications such as leading edges and combustor panels.
|
From page 32... ...
Nevertheless, through a balanced combination of hypersonics high-enthalpy facility testing and numerical simulation, tunnel free stream conditions can be well characterized, and new and important effects can be discovered that will contribute to the development of vehicle design tools. New flow variables that come with high enthalpy, such as vibrational excitation and species concentration, can be measured by modern optical diagnostic techniques, which have, however, only been applied to high-enthalpy ground testing facilities in a few very limited cases.
|
From page 33... ...
· Guidance to program direction Revolutionary Concepts Panels High-Speed/ Space Access Space · Convened as necessary Hypersonics Technology · Report to Executive Director and Lead: AF Lead: NASA Lead: NRO/AF pillar leads as appropriate Deputy: NASA Deputy: AF Deputy: DARPA · Seek revolutionary approaches and solutions to topical/critical Lead/Deputy may rotate technical issues Army Liaison Navy Liaison DARPA Liaison FIGURE 2-3 Structure of the NAI Executive Director's Office.
|
From page 34... ...
NAI should develop a concise description of its goals and objectives, giving equal weight to early applications achievable in the near and medium term, including hypersonic missiles and aircraft that are already part of the HS/H pillar. Recommendations 2-10, 2-11, and 2-12 are found in the first subsection of the section that follows, "Hypersonic Flight Critical Technologies." HYPERSONIC FLIGHT CRITICAL TECHNOLOGIES This section covers the technologies that are critical for air-breathing hypersonic flight and discusses their current readiness levels.
|
From page 35... ...
35 of Area page)
|
From page 36... ...
2 2.5 2.5 1.5 3 2.5 3 3 3 2.5 2 transfer tanks Technology tanks geometry data grid edges protection optimization Areas cryogenic Constituent Seals Sensors Al Graphite-epoxy cryogenic Leading Thermal systems Structure Parametric Automated Automated generation Robust Continued Technology 2-1 vehicle MDO materials Technology and TABLE NAI-Defined Major Area Airframe Integrated design tools
|
From page 37... ...
37 sections various in ed us High both are 9, through 1 scales. of both scale on a High Medium Low Low Low Medium Low with technologies levels, evaluate readiness to Moderate Extreme Extreme Extreme Significant Extreme Significant reader [5]
|
From page 38... ...
Table 2-1 should help to determine if appropriate attention is being paid to the technologies supporting the NAI goals. Air-Breathing Propulsion and Flight Demonstration Propulsion is foremost among the critical technologies that will enable air-breathing hypersonic flight, not only for the dual-mode ramjet/scramjet engines that will achieve hypersonic speeds but also, although to a lesser degree, for the low-speed engines that will accelerate to ramjet/scramjet takeover speeds (typically Mach 3 to 4)
|
From page 39... ...
Availability of propulsion systems ready for full-scale development (FSD) by 2018 also requires thorough definition and planning of the fundamental research, component technology development, and ground testing and flight demonstrations required to mature full-scale engines to the point where they can be used for operational hypersonic flight.
|
From page 40... ...
Flight is also required to demonstrate engine mode transitions; to fully characterize engine and airframe thermal environments across the speed regime; to demonstrate the durability, effectiveness, and operational utility of integrated airframe-TPS and engine thermal management systems; and to validate the performance of highly integrated hypersonic vehicles designed using integrated analysis and multidisciplinary optimization techniques (see subsection on integrated vehicle design)
|
From page 41... ...
600 ($ 400 200 Next Generation Launch Technology 0 FY 03 FY 04 FY 05 FY 06 FY 07 FY 08 FY03 BAU FY 03 FY 04 FY 05 FY 06 FY 07 FY 08 Orbital Space Plane 295.7 383.3 550.1 609.9 716.6 894.7 916.0 Next Generation Launch Technology 583.7 767.1 514.5 513.8 504.7 362.3 307.4 Space Launch Initiative Total 879.4 1,150.4 1,064.6 1,123.7 1,221.3 1,257.0 1,223.4 FIGURE 2-5 Space Launch Initiative full cost budget (FY 2003 reflects estimated full cost)
|
From page 42... ...
Instead, this report will focus on three important areas of materials technology, as follows: · Thermal protection systems (TPSs) , · Actively cooled combustor panels, and · Cryogenic tanks.
|
From page 43... ...
Free Stream Uncooled 2000 Alloys Total Material Limits Ti Temperature 1000 Al 0 0 1 2 3 4 5 6 7 8 9 10 Mach Number FIGURE 2-6 Combustor wall temperature as a function of Mach number. Active cooling is required in the combustor.
|
From page 44... ...
However, to attain Mach 15 in a large-scale vehicle by 2018 would probably require increasing the materials technology investment by a factor of 5 to 10, resulting in a total investment level of $150 million to $200 million per year. Integrated Vehicle Design and Multidisciplinary Optimization Integrated vehicle design and multidisciplinary optimization have been identified by the committee as a critical technology for the HS/H pillar of the NAI.
|
From page 45... ...
In addition to the previously mentioned weaknesses in applying MDO to conventional aircraft design, the hypersonic vehicle designer must be able to construct high-fidelity fluid dynamics surrogates in the hypersonic regime. The construction of high-fidelity hypersonic fluid dynamic surrogates will require the following:3 · Improved understanding and modeling of shock and turbulent boundary layer interactions, · Measurements of nitrogen oxide and other species to support high-enthalpy wind tunnel studies, · Accurate modeling of finite-rate chemistry effects on turbulent boundary layers, · Validation and verification (V&V)
|
From page 46... ...
It must be emphasized that the problems specific to hypersonic vehicle design are long term and will require several more years of adequate and sustained funding at a level of several tens of millions more dollars to fully solve. 4Accessed at http://www.phoenix-int.com/products/ModelCenter.html.
|
From page 47... ...
At Mach numbers greater than, say, 8, the stagnation temperature is greater than 3000 K, and above Mach 12, greater than 7000 K Materials from which ground test facilities are made cannot sustain associated heat loads for extended periods, so that short-duration methods such as shock tunnels and expansion tubes must be resorted to.
|
From page 48... ...
Existing and Projected Ground Testing Facilities The facilities existing in the United States for testing at enthalpies corresponding to Mach numbers greater than 10 include the shock tunnels and the expansion tunnel at the Calspan-University of Buffalo Research Center, Inc.
|
From page 49... ...
1. One purpose of combining ground testing with computation is to produce validated computational tools that can subsequently be used in design.
|
From page 50... ...
Technology Readiness Levels TRLs in the integrated ground test and numerical simulation/analysis area are as follows: · High-enthalpy ground test facilities (subject to earlier described limitations) : 5-6 (see Figure 2-7 for perceived upgrade needs and costs)
|
From page 51... ...
2002. CFD valida tion for hypersonic flight: Hypersonic double-cone flow experiment.
|
From page 52... ...
Briefing by Charles McClinton, NASA Langley, to the Committee on the National Aerospace Initiative. September 4.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.