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This paper presents the derivation of the equations for circumferential, longitudinal and radial heat transfer conductance for a thin shell toroid or a segment of the toroid. A thin shell toroid is one in which the radius to thickness ratio is greater than 10. The equations for the surface area of a toroid or of a toroidal segment will also be derived along with the equation to determine the location of the centroid. The surface area is needed to determine the radial conductance in the toroid or toroidal segment and the centroid is needed to determine the heat transfer center of the toroid or toroidal segment for circumferential and longitudinal conductance. These equations can be used to obtain more accurate results for conductive heat transfer in toroid which is a curved spacecraft components. A comparison will be made (1) using the equations derived in this paper which takes into account the curvature of the toroid (true geometry) and (2) using flat plates to simulate the toroid.

This Life Support Laboratory consists of a simulator of the spacecraft called Nautilus, which houses Air Revitalization Subsystem, Atmospheric Control and Supply, and Fire Detection and Suppression in the Equipment Area. There are supporting facilities including a Human Metabolic Simulator, simulated Low and Moderate Temperature Coolant Loop, chemical analysis bench, purified water supply, vacuum and gas supplies. These facilities are scheduled to be completed and start to operate for demonstration purposes by March 2005. There are an ARES Ground Model (AGM) and a Trace Contaminant Control Assembly in the ARS. The latter will be integrated with the AGM and a Condensing Heat Exchanger. The unit of AGM is being engineered, built, and will be delivered in early 2005 by EADS Space Division. These assemblies will be operated for sensitivity analysis, integration and optimization studies. The main goal is the achievement for optimal recovery of oxygen.

HEAT TRANSFER causes loading and starting design problems in large missile systems powered by cryogenic propellants. This manifests itself during loading as effective density variation, violent surface conditions, boiloff, and ice formation — problems which may be solved by insulating the tank. During starting it causes overheating and caviation — effects which may be reduced by recirculators and subcooled charge injections. The study described in this paper centers around liquid oxygen and its variations in heat flux rate, which affect liquid density, surface condition, and replenishing requirements. The problem areas are made apparent by consideration of a hypothetical missile system.*

A “next generation” condensing heat exchanger for space systems has to satisfy demanding operational requirements under variable thermal and moisture loads and reduced gravity conditions. Mathematical models described here are used to investigate transient behavior of wetting and de-wetting dynamics in the binary porous system of porous tubes and porous cold plate. The model is based on the Richard's equation simplified for the zero-gravity conditions. The half-saturation distance or the zone of influence of the porous annular suction tubes on the cold-plate porous material will be in the range of 1 to 10 cm for the time scales ranging from 100 to 10,000 seconds and moisture diffusivity in the range of D = 10-4 to 10-6 m2/s.

Spacecraft life support equipment is often challenged with two phase flow, where liquid and gas exist together. In the zero gravity environment of an orbiting spacecraft, the behavior of a liquid/gas interface is dominated by forces not usually observed in one “G” due to the overwhelming effects of gravity. The normal perceptions no longer apply. Water does not run down hill and bubbles do not rise to the surface. Surface energy, capillary forces, wetting characteristics and momentum effects predominate. Techniques and equipment have been developed to separate the liquid/gas mixture into its constituent parts with various levels of efficiency and power consumption.

This paper investigates the use of several zero-ozone depleting potential (zero-ODP) HFC refrigerants, including HFC-134a, HFC-227ca, HFC-227ea, HFC-236ea, HFC-236cb, HFC-236fa, HFC-245cb, and HFC-254cb, for centrifugal chiller applications. We took into account the thermodynamic properties of the refrigerant and aerodynamic characteristics of the impeller compression process in this evaluation.. For a given operating temperature lift, there are significant differences in the pressure ratio required by each refrigerant and this variation in pressure ratio directly affects compressor size, efficiency, and performance. A comparison of the HFC refrigerant candidates with CFC-114 shows that HFC-236ea, HFC-227ca and HFC-227ea are viable alternatives for centrifugal water chillers. HFC-236ea has properties closest to CFC-114, and will result in comparible performance, but will require a slightly larger impeller and a purge system.

The X-29 Fuel/Auxiliary Oil Thermal Management System provides total aircraft accessory oil cooling, including both flight and combined hydraulics, Integrated Drive Generator oil, and Accessory Drive Gearbox oil, with onboard fuel. Fuel cooling rates that are independent of engine demand are achieved through the use of a recirculation loop. Recirculation is minimized by maintaining the engine fuel inlet temperature at the maximum allowable. Fuel cooling results in lower, more uniform subsystem oil temperatures, less ram drag, and smaller, lighter-weight heat exchangers. Initial design studies and laboratory development testing will be discussed, along with comparisons of analytical predictions with flight test results.

Selection of working fluid is one of the main criterions for designing of heat pipes thermal control systems (TCS) for space application. In this paper we will describe how we solved the task of development of the TCS with working fluid of high thermal physical properties. In 2004-2006 we developed the Engineering model of Deployable Radiator based on Loop Heat Pipe by CAST purchase order. It was developed for qualification tests. Ammonia application as LHP working fluid is stipulated by its high thermal physical properties. However Ammonia freezing temperature is of minus 77ºC. Such fact impedes Ammonia application when operation temperatures of LHP Radiator are lower than this value, for example, It takes several tens of hours to orbit a spacecraft and prepare it for work (at that moment the spacecraft is out of power supply) and the working fluid can be frozen in a condenser-radiator when the spacecraft being in the shadow over a long period of time.

This paper discusses the importance of enroute wind conditions and the need for a wind measurement system which provides accurate and timely observations of wind and temperature conditions aloft. Recent advances in remote measurement of winds, temperature, and humidity such as the Stratospheric-Tropospheric radars and profilers developed at the National Oceanic and Atmospheric Administration’s Environmental Research Lab form the basis of such a system. A domestic system could and should be established using these devices together with a near real time winds aloft data dissemination network. Estimates of the saving in aircraft fuel consumption benefits range from 1 to 3 percent per year, or from $ 100 to $ 300 million for U.S. aviation system users at current prices and consumption.

This paper is concerned with the development of statistical models for the gust field in the lowest 300 ft of the atmosphere. It presents some of the highlights of the underlying physics principles, what is known about gusts, and how gusts affect aircraft. The difficulties of developing gust models are accounted for by the lack of data in particular areas and thus direct attention to the work required to provide the needed information.

Unmanned Aerial Vehicles (UAV) are being deployed in military, law enforcement, search & rescue, scientific research, environmental & climate studies, reconnaissance and other commercial and non-commercial applications on a large scale. A design and development of landing gear system has been taken up for a UAV. This paper presents the design optimization of structural components of Wheel-Brake & Fork assembly pertaining to the Main Landing Gear (MLG) for a UAV. The wheel, fork, axle and brake unit constitute the wheel assembly. The wheel-brake assembly is assembled with the strut assembly and forms the Landing gear system. The Fork is the connecting member between the shock strut and the axle containing the wheel-brake assembly. As the fork and axle are subjected to shock loads while landing, the strength of these components are very much essential to withstand the dynamic loads.

Premature wearout of augmentor hydraulic fuel pumps was being experienced in service on a fighter aircraft engine. The removal times ranged from 150 to 800 engine operating hours. Considerable effort had gone into the understanding of the physics of failure and overcoming this problem in a modified pump. However, there still remained the question of how best to proof test the new pump. The challenge was to demonstrate that the redesigned pump was significantly better than the old pump. The problems faced during design verification will be discussed in this case study. For example, does an accelerated test duplicate the service failure mode? When has an accelerated test run long enough to prove the redesign is in fact better than the old product? This paper illustrates the application of new technology to solve these research and development program problems through the use of Weibull and Weibayes Analysis.

The Environmental Control System (ECS) of an aircraft provides thermal and pressure control of the engine bleed air for comfort of the crew members and passengers onboard. For safe and reliable operation of the ECS under complex operating environments, it is critical to detect and diagnose performance degradations in the system during early phases of fault evolution. One of the critical components of the ECS is the heat exchanger, which ensures proper cooling of the engine bleed air. This paper presents a wavelet-based fouling diagnosis approach for the heat exchanger.

The Water Supply Assembly (WSA) is part of the Liquid Management Section (LMS) of the Hermes Environmental Control and Life Support Subsystem (ECLSS) (see ref. [1] and [2]). The WSA has to provide pure water for drinking and food preparation (rehydratation of dry food and beverage powder) and to provide pure water for hygiene purposes (oral hygiene and towel wetting). To obtain different desired temperatures (as well as different quantities of water to be dispensed), a heating device, using electrical foils, and a cooling device, using a water/water heat exchanger have been designed with regard to the critical mass and power requirements. Two dispensers are used to fill food/beverage or hygiene (towels) containers. As part of the Hermes C1 phase, breadboard models of the heating device (heater) and of the cooling device (chiller) have been manufactured and functionally tested.

A Suit Water Membrane Evaporator (SWME) system was designed at JSC, NASA, for the Advanced Space Suit Portable Life Support System (PLSS). The SWME was investigated to provide a more robust and reliable method of heat transfer for PLSS heat load, providing an alternate technology to the current Shuttle EMU sublimator. The SWME is less sensitive to water contamination, provides gas venting capability to the PLSS thermal loop, and permits control of heat transfer rate via back pressure regulation. The tests served as a technology demonstration of SWME performance in a concentric, dual-sided design configuration, back pressure regulation under water vapor condition, and combined system compatibility. The tests provided preliminary data to characterize SWME performance and investigate the viability of backpressure regulation control.

Water recovery from wastewater is essential for the success of long term missions. Honeywell Aerospace and the team comprising Thermodistillation Co. (Kiev, Ukraine) and NASA JSC Crew and Thermal Systems Division are developing an advanced wastewater processing subsystem that is based on centrifugal vacuum distillation that will be tested at the NASA JSC water lab. The wastewater processing cascade distillation subsystem (CDS) utilizes a multi-stage thermodynamic process to efficiently produce purified water, and its rotary centrifugal design provides gas/liquid phase separation and liquid transport (pumping) under microgravity conditions. The objective of the program is to demonstrate potable water recovery from various wastewater streams that is suitable to meet the requirements of present (ISS) and future (Lunar-Mars) human space missions. This paper presents the subsystem design and the cascade distiller operational evaluation.

An analysis is presented of the relative suitability of sodium, potassium, rubidium, and cesium as working fluids in a high temperature, Rankine Cycle, space power plant. Turbine inlet temperatures of from 1800 to 2000 F with corresponding condensing temperatures of from 1240 to 1530 F are considered. The criteria by which the fluids are evaluated are the thermodynamic cycle characteristics, heat transfer and fluid friction characteristics, metallurgical compatibility, and the influence of the fluids on the design of the turbine, bearings, radiator, generator, and pump. The turbogenerator unit is thought to be the most critical component and it is found that the working fluid will determine the required number of turbine stages and will therefore establish the turbogenerator bearing arrangement. It is not known whether blade erosion will be a problem.

Through microscopic visualization experiments, a process generally known as depth filtration was shown to be caused by surface pores. Moreover, the existence of a soot cake layer was an important advantage for filtration performance because it could trap most of the particulates. We proposed an ideal diesel particulate filter (DPF), in which a silicon carbide (SiC) nanoparticle membrane (made from a mixture of 80 nm and 500 nm powders) instead of a soot cake was sintered on the DPF wall surface; this improved the filtration performance at the beginning of the trapping process and reduced energy consumption during the regeneration process. The proposed filter was called a diesel particulate membrane filter (DPMF). A diesel fuel lamp was used in the trapping process to verify the trapping and oxidation mechanisms of ultrafine particulate matter. Thus, the filtration performance of the membrane filters was shown to be better than that of conventional DPFs.

Failure analysis of engineering systems typically emphasizes identification and mitigation under an independent failure assumption with dependent failures treated as the exception rather than the rule. Some frameworks for addressing dependent failures through analysis appear in standards including NUREG 0492, ISO 26262, MIL-1629-A, and ARP4761 amongst others. The purpose of identifying these dependencies is to allow system analysts to determine and quantify the factors that influence dependent fault probabilities. Once identified, failure relationships can be incorporated into a Discrete Event Simulation (DES) of the system, providing a mathematically rigorous estimate of system utility (e.g., availability, reliability). The output of a simulation can provide an expected value of performance but additionally, can also allow the analyst to identify the downstream impact of probabilistic dependencies between system elements.

Vehicle suspension is a critical system which influences vehicle stability, ride comfort and finally the performance of the car. Designing a good suspension will positively influence the customer perception of the ride comfort and handling of the vehicle. In the present scenario, large electrification drive across the globe in the automotive sector are encouraging the manufacturers to explore the possibility of replacing the engine with the electric motor and battery in a conventional vehicle. Dynamic characteristics of the vehicle may vary due to change in mass distribution and center of gravity of the vehicle, which in turn will have an impact on the suspension characteristics. To avoid the negative impact on the ride and handling, suspension characteristics like pitch, bounce, roll, wheel rate, camber angle, toe in/out need to be reassessed and modified. They are likely to impact suspension geometry and vehicle stability during maneuvers involving oversteer and understeer.