Degradation of a Multilayer Insulation Due to a Seam and a Penetration

The degradation of the thermal performance of a multilayer insulation due to the presence of a seam and a penetration was studied. The multilayer insulation had 30 aluminized Mylar radiation shields with silk net spacers. The seam, an offset butt joint, caused a heat input of 0.169 watt per meter in addition to the basic insulation thermal performance of 0.388 watt per square meter obtained before the installation of the butt joint. The penetration, a fiberglass tank support strut, provided a heat input (including the degradation of the insulation) of 0.543 watt in addition to the basic insulation thermal performance of 0.452 watt per square meter obtained before the penetration

Comparison of reusable insulation systems for cryogenically-tanked earth-based space vehicles

Three reusable insulation systems concepts were developed for use with cryogenic tanks of earth-based space vehicles. Two concepts utilized double-goldized Kapton (DGK) or double-aluminized Mylar (DAM) multilayer insulation (MLI), while the third utilized a hollow-glass-microsphere, loadbearing insulation (LBI). Thermal performance measurements were made under space-hold (vacuum) conditions for insulating warm boundary temperatures of approximately 291 K. The resulting effective thermal conductivity was approximately 0.00008 W/m-K (W = weight,Kg; m = measured; K = temperature) for the MLI systems (liquid hydrogen test results) and 0.00054 W/m-K for the LBI system (liquid nitrogen test results corrected to liquid hydrogen temperature)

Development of improved-durability plasma sprayed ceramic coatings for gas turbine engines

As part of a NASA program to reduce fuel consumption of current commercial aircraft engines, methods were investigated for improving the durability of plasma sprayed ceramic coatings for use on vane platforms in the JT9D turbofan engine. Increased durability concepts under evaluation include use of improved strain tolerant microstructures and control of the substrate temperature during coating application. Initial burner rig tests conducted at temperatures of 1010 C (1850 F) indicate that improvements in cyclic life greater than 20:1 over previous ceramic coating systems were achieved. Three plasma sprayed coating systems applied to first stage vane platforms in the high pressure turbine were subjected to a 100-cycle JT9D engine endurance test with only minor damage occurring to the coatings

Transient thermal performance of multilayer insulation systems during simulated ascent pressure decay

Transient thermal performance of multilayer insulation systems with liquid hydrogen tank during simulated Saturn 5 ascent pressure deca

EXPERIMENTAL INVESTIGATION OF THE SLOSH-DAMPING EFFECTIVENESS OF POSITIVE-EXPULSION BAGS AND DIAPHRAGMS IN SPHERICAL TANKS

Slosh damping effectiveness of positive expulsion bags and diaphragms in spherical tank

Experimental investigation of liquid sloshing in a scale-model Centaur liquid-hydrogen tank

Liquid sloshing in scale model Centaur liquid hydrogen tan

DNA barcodes and new primers for nature's pest controllers: the social wasps

Globally, biodiversity is declining because of anthropogenic pressures, and this could lead to extinction of some species before they are discovered. The loss of insect taxa is of prime concern, given recent reports of significant declines in the populations of many taxa across the globe. Efforts to document biodiversity have met with several challenges, amongst which are the difficulties in using morphological features to discriminate species, especially in insects. DNA barcoding is a rapid and reliable method for species identification and discovery but choosing appropriate primers to amplify the barcode region without co-amplifying contaminants remains a key challenge. We developed and tested a set of primers for PCR amplification of the DNA barcode region of the COI gene in polistine wasps.Zethus miniatus Saussure. Samples were obtained from Africa, Americas, Asia, and Europe. The polistine-specific primers successfully amplified the barcode region for all polistines tested, without amplifying any Wolbachia present; they also worked with many species from the other Vespidae wasp subfamilies. The new primers are valuable for the discovery and accurate documentation of polistine wasps in the four continents

Liquid propellant reorientation in a low-gravity environment

An existing empirical analysis relating to the reorientation of liquids in cylindrical tanks due to propulsive settling in a low gravity environment was extended to include the effects of geyser formation in the Weber number range from 4 to 10. Estimates of the minimum velocity increment required to be imposed on the propellant tank to achieve liquid reorientation were made. The resulting Bond numbers, based on tank radius, were found to be in the range from 3 to 5, depending upon the initial liquid fill level, with higher Bond number required for high initial fill levels. The resulting Weber numbers, based on tank radius and the velocity of the liquid leading edge, were calculated to be in the range from 6.5 to 8.5 for cylindrical tanks having a fineness ratio of 2.0, with Weber numbers of somewhat greater values for longer cylindrical tanks. It, therefore, appeared to be advantageous to allow small geysers to form and then dissipate into the surface of the collected liquid in order to achieve the minimum velocity increment. The Bond numbers which defined the separation between regions in which geyser formation did and did not occur due to propulsive settling in a spherical tank configuration ranged from 2 to 9 depending upon the liquid fill level

Thermal performance of gaseous-helium-purged tank-mounted multilayer insulation system during ground-hold and space-hold thermal cycling and exposure to water vapor

An experimental investigation was conducted to determine (1) the ground-hold and space-hold thermal performance of a multilayer insulation (MLI) system mounted on a spherical, liquid-hydrogen propellant tank and (2) the degradation to the space-hold thermal performance of the insulation system that resulted from both thermal cycling and exposure to moisture. The propellant tank had a diameter of 1.39 meters (4.57ft). The MLI consisted of two blankets of insulation; each blanket contained 15 double-aluminized Mylar radiation shields separated by double silk net spacers. Nineteen tests simulating basic cryogenic spacecraft thermal (environmental) conditions were conducted. These tests typically included initial helium purge, liquid-hydrogen fill and ground-hold, ascent, space-hold, and repressurization. No significant degradation of the space-hold thermal performance due to thermal cycling was noted

Copper Indium Disulfide Nanocrystal Luminescent Solar Concentrators

The sun is the most prominent renewable energy resource. Technologies such as photovoltaics (PVs) have yet to emerge as a cost effective alternative to non-renewable energy resources such as fossil fuels. Luminescent solar concentrators (LSC) possess the ability to lower the cost of solar energy by the reduction of the photovoltaic cell area and yet increase photovoltaic conversion efficiency. LSC’s offer an attractive approach to concentrating both specular and diffuse light, which eliminates expensive solar tracking methods. Luminophores for LSC applications are often dominated by reabsorption losses and absorb a small part of the solar spectrum, which prevents LSC’s from being a competitor in today’s energy market. This thesis introduces a new class of luminophore for use in LSCs based on Copper Indium Disulfide (CIS). CIS has a broad absorption spectrum from the Ultraviolet to near-infrared with a tunable emission output, high photoluminescent quantum yield, and large effective stokes shift making them the current best LSC luminophore