HYPERFIRE

Traditionally, unsteady pressure transducers have been the instrumentation of choice for investigating unsteady flow phenomena which can be time-consuming and expensive. The ability to measure and compute these flows has been a long-term challenge for aerospace vehicle designers and manufacturers. Results using only the pressure transducers are prone to inaccuracies, providing overly conservative load predictions in some cases and underestimating load predictions in other areas depending on the flow characteristics. NASA Ames has developed a new state-of-the-art method for measuring fluctuating aerodynamic-induced pressures on wind tunnel models using unsteady Pressure Sensitive Paint (uPSP). The technology couples recent advances in high-speed cameras, high-powered energy sources, and fast response pressure-sensitive paint. The unsteady pressure-sensitive paint (uPSP) technique has emerged as a powerful tool to measure flow, enabling time-resolved measurements of unsteady pressure fluctuations within a dense grid of spatial points on a wind tunnel model. The invention includes details surrounding uPSP processing. This technique enables time-resolved measurements of unsteady pressure fluctuations within a dense grid of spatial points representing the wind tunnel model. Since uPSP is applied by a spray gun, it is continuously distributed. With this approach, if the model geometry can be painted, viewed from a camera, and excited by a lamp source, uPSP data can be collected. Unsteady PSP (uPSP) has the ability to determine more accurate integrated unsteady loads.

Advances in new polymers and composites along with growing industrial needs in below-ambient temperature applications have brought about the Macroflash development. Accurate thermal performance information, including effective thermal conductivity data, are needed under relevant end-use conditions. The Macroflash is a practical tool for basic testing of common materials or research evaluation of advanced materials/systems. The Macroflash can test solids, foams, or powders that are homogeneous or layered in composition. Test specimens are typically 75mm in diameter and 6mm in thickness. The cold side is maintained by liquid nitrogen at 77 K while a heater disk maintains a steady warm-side temperature from ambient up to 373 K. The steady boiloff of the liquid nitrogen provides a direct measure of the heat energy transferred through the thickness of the test specimen. Nitrogen or other gas is supplied to the instrument to establish a stable, moisture-free, ambient pressure environment. Different compression loading levels can also be conveniently applied to the test specimen as needed for accurate, field-representative thermal performance data. The Macroflash is calibrated from approximately 10 mW/m-K to 800 mW/m-K using well-characterized materials.

Cryostat-100 combines the best features of previous cryostats developed by NASA, while offering new features and conveniences. This unit can readily handle the full range of cryogenic-vacuum conditions over several orders of magnitude of heat flux. Guide rings, handling tools, and other design items make insulation change-out and test measurement verification highly reliable and efficient to operate. The new apparatus requires less ancillary equipment (it is not connected to storage tank, phase separator, subcooler, etc.) to operate properly. It is top-loading, which makes disassembly, change-out, and instrumentation hook-up much faster. The thermal stability is improved because of internal vapor plates, a single-tube system of filling and venting, bellows feed-throughs, Kevlar thread suspensions, and heavy-wall stainless-steel construction. The cold mass of Cryostat-100 is 1m long, with a diameter of 168 mm. The test articles can therefore be of a corresponding length and diameter, with a nominal thickness of 25.4 mm. Shorter lengths are acceptable, and thicknesses may be from 0 mm to 50 mm. Tests are conducted from ambient pressure (760 torr) to high vacuum (below 110-4 torr) and at any vacuum pressure increment between these two extremes. The residual gas (and purge gas) is typically nitrogen but can be any purge gas, such as helium, argon, or carbon dioxide. Typically, eight cold vacuum pressures are performed for each test series. The warm boundary temperature is approximately 293 K, and the cold boundary temperature is approximately 78 K. The delta temperature for the cryogenic testing is therefore approximately 215 K. A unique lift mechanism provides for change-out of the insulation test specimens. It also provides for maintenance and other operations in the most effective and time-efficient ways. The lift mechanism is also a key to the modularity of the overall system.

The Cryostat-500 provides laboratory measurement of the steady-state thermal transmission properties of thermal insulation systems under conditions below ambient temperature. Liquid nitrogen is used as a direct measure of the energy going through the test specimen. Thermal insulation systems may be composed of one or more materials that may be homogeneous or non-homogeneous at boundary conditions from 77 K to 373 K and in environments from high vacuum (10E-7 torr) to ambient pressure (10E+3 torr). The Cryostat-500 provides a much wider range of thermal performance and covers the full range of environmental conditions for applications below ambient temperature. The instrument has been proven through extensive testing of foams, composite panels, multilayer insulation (MLI) systems, aerogel blankets, fiberglass, and many other types of materials. Both the quality and quantity of the thermal performance data for insulation materials and systems have increased even as the process and method has become more time efficient and cost effective. Further guidelines on the test method and equipment for the Cryostat-500 are given in ASTM C1774, Annex A3.

LWDC technology enables an improved channel wall nozzle with an outer liner that is fused to the inner liner to contain the coolant. It is an additive manufacturing technology that builds upon large-scale cladding techniques that have been used for many years in the oil and gas industry and in the repair industry for aerospace components. LWDC leverages wire freeform laser deposition to create features in place and to seal the coolant channels. It enables bimetallic components such as an internal copper liner with a superalloy jacket. LWDC begins when a fabricated liner made from one material, Material #1, is cladded with an interim Material #2 that sets up the base structure for channel slotting. A robotic and wire-based fused additive welding system creates a freeform shell on the outside of the liner. Building up from the base, the rotating weld head spools a bead of wire, closing out the coolant channels as the laser traverses circumferentially around the slotted liner. This creates a joint at the interface of the two materials that is reliable and repeatable. The LWDC wire and laser process is continued for each layer until the slotted liner is fully closed out without the need for any filler internal to the coolant channels. The micrograph on the left shows the quality of the bond at the interface of the channel edge and the closeout layer; on the right is a copper channel closed out with stainless.