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There is a need for a space launch system that can provide ready, reliable, unencumbered access to space. The need exists for a highly reliable launch system that can operate from numerous available sites, that can provide all azimuth launch capability, that is fully reusable, and that can carry significant payloads into low earth orbit. A vehicle concept was developed to demonstrate the ability of near term aeromechanics and propulsion technology to support such a system. The vehicle was composed of two stages. The system takes off horizontally and both stages return to a horizontal landing. Turbojet, ramjet, and rocket propulsion is used. The sensitivity of the system to thrust, drag, weight, and staging Mach number was examined. The two stage system is able to accommodate a range of performance variations yet still retain significant mission potential.

The US space program is facing the dilemma of the federal government reducing in size, the Congress asking for lowered costs, and the US market share of commercial launches declining. While several new launch vehicle options have been studied and advocated, a national plan has yet to be adopted. Despite this, there may be compelling solutions that await discovery. This paper suggests a particular TSTO launch system may solve the dilemma, but only if some of the past presumptions and guidelines are viewed as impediments to be overcome instead of “realities”.

Unmanned Aerial Vehicles (UAV) require simple and reliable engines of high power to weight ratio. Wankel and two stroke engines offer many advantages over four stroke engines. A two stroke engines featuring crank case scavenging, precise oiling, direct injection and jet ignition is analyzed here by using CAD, CFD and CAE tools. Results of simulations of engine performances are shown in details. The CFD analysis is used to study fuel injection, mixing and combustion. The CAE model then returns the engine performances over the full range of loads and speeds with the combustion parameters given as an input. The use of asymmetric rather than symmetric port timing and supercharging scavenging is finally suggested as the best avenue to further improve power density and fuel conversion efficiency.

Contemporary Technical opinion is that a second generation Supersonic Transport will need to be commercially viable and meet environmental noise and emissions. Rolls-Royce and SNECMA have identified that engines with large variability (Flow Multiplication) will be needed. Two engine designs have been developed for this requirement and their characteristics identified. Both potentially reduce the cruise fuel consumption by up to 10% from that of the Olympus in Concorde and the subsonic fuel consumption by better than 15%. All this with some 35 to 45% improvement in thrust weight ratio. These two designs are a Tandem Fan system and MCV99 Mid Fan system and the essential difference is a trade of weight and friction drag due to the larger intake, nacelle and nozzle of the one, versus wave drag due to a larger maximum cross section of the other.

Discussion of attainment of mutual goals of builder and operator through pointing out some areas in which important gains can be made. Major portion of discussion is devoted to hardware and other inanimate objects or physical phenomena.

The regenerate two-bed carbon dioxide removal system, utilizing carbon molecular sieve (CMS), represents a significant advancement over the current Space Station four-bed zeolite molecular sieve baseline system. To demonstrate the feasibility of the CMS system approach. AiResearch conducted system performance tests on a two-bed system created by modifying the existing flight qualified Skylab regenerable carbon dioxide removal system. Results of the performance tests confirmed the two-bed CMS system approach as a viable candidate for Space Station regenerable carbon dioxide removal.

A method has been developed for deriving “effective” thermal properties for charring composite materials which yield accuracy equivalent to the best charring models. Such “effective” properties have application for two- and three-dimensional thermal analyses where appropriate charring codes either do not exist or would be prohibitively expensive.

This work summarizes the limitations of the Ideal Gas Law and the use of simple but accurate two-parameter equations of state for air, oxygen, and nitrogen in the operations of ECLS/EVA hardware. The equation-of-state parameters can be determined for pure gases and for mixtures by mixture combination rules. The parameters of two equations of state in Redlich-Kwong equation of state and Peng-Robinson equation of state have been calculated here. Technical evaluations for spacecraft applications and relevant ranges in temperatures and pressures have been performed. The equations are applicable for several ECLS subsystems: Temperature and Humidity Control, THC; Atmospheric Revitalization System, ARS; and Atmospheric Control System, ACS. The goal is to focus on equations of state for ECLS/EVA applications, especially in depress/repress/compression of air and gases.

Future large spacecraft such as the Space Station will have high power dissipations and long heat transport distances. The combination of these two requirements dictate the need for a new heat transport technology. Boeing Aerospace developed an ammonia thermal bus (ATB) concept using two-phase ammonia as the working fluid. Instrumentation and control systems were used to verify system performance, protect personnel and equipment safety, and run the system. The ATB was robust; thus operating procedures were simple and fault tolerant. Test results demonstrated a maximum heat load of 22 kW, a controllable turndown ratio of 44:1, and the ability to control setpoint temperatures within the range of 30 to 90°F. This paper describes the ammonia thermal bus (ATB), test instrumentation and control, procedures for operating the ATB, and test results.

This paper presents the general objectives, the design concept and the potential performances of the two-phase capillary pumping loop (CPL) as a heat transportation system. In particular the actual design of the ESA funded development program “CPL”, designed and developped by SABCA and DORNIER will be shown as well as of its development status. Results obtained with the first breadboard CPL model are reported together with comparison of predicted against tested performances.

Developing headers to uniformly distribute two-phase (liquid/vapor) flow is a difficult but important aspect in the design of advanced two-phase thermal control systems. This paper documents experimental efforts toward developing a header to equally distribute the liquid flow to parallel legs of a two-phase heat exchanger. Models of various header concepts were built and tested using air/water mixtures to simulate two-phase liquid/vapor flow. Based on the results of these tests, a Fan Header concept was designed for a specific, parallel tube heat exchanger. At flow rates within the expected range of operation, this Fan Header distributed the liquid within 16% of the equally distributed value for inlet qualities up to 25%.

Two-phase flow and heat transfer is an important technology for future development of interplanetary spacecraft thermal control, planetary-based power generation systems, and hypersonic vehicle thermal protection. This paper presents several analytical considerations for the prediction of two-phase flow and heat transfer. Two specific examples are explained; the first is that of two-phase natural convection and the second is that of an evaporating two-phase flow.

For long-duration space missions, the life support and In-Situ Resource Utilization (ISRU) systems necessary to lower the mass and volume of consumables carried from Earth will require more sophisticated chemical processing technologies involving gas-liquid two-phase flows. This paper discusses some preliminary two-phase flow work in packed columns and generation of bubbly suspensions, two types of flow systems that can exist in a number of chemical processing devices. The experimental hardware for a co-current flow packed column operated in two ground-based low gravity facilities (two-second drop tower and KC-135 low-gravity aircraft) is described. The preliminary results of this experimental work are discussed. The flow regimes observed and the conditions under which these flow regimes occur are compared with the available co-current packed column experimental work performed in normal gravity.

Aspects of the gravitational scaling of spacecraft two-phase heat transport systems are discussed. Supporting similitude considerations, based on dimension analysis, and useful equations and correlations are given.

Based on the thermal requirements of future large European platforms such as the Columbus Space Station, several developments in the field of two-phase flow systems were initiated over the last few years in Europe. This paper will give a general overview of the objectives, development status and test results of an ESA-funded ‘Two-phase heat transport system’ study and of two studies sponsored by the German Ministry of Research and Technology on two-phase heat transport. The ESA two-phase loop system resulting from the concept trade-off is driven by an electrically powered liquid pump and is provided with a capillary cold plate and an evaporative heat exchanger mounted in parallel. Under certain conditions, a simplified version of this type of system is able to work in a capillary-pumped mode. The system is designed for a heat load of 10-20 KW, a length of 20 m, a working temperature around 20°C and R114 as working fluid.

This paper describes advanced heat acquisition and transport components developed and tested as part of the Two-Phase Survivable Thermal Management (TSTM) Program. The components are: a pumped heat pipe coldplate capable of removing very high-flux waste heat loads with a minimum temperature drop; and a thermal transport system designed to transport large quantities of waste heat over large distances with a long life and low power consumption. These components are intended for use in an advanced thermal control system which removes waste heat from high-power spacecraft. For the heat acquisition component, a successful design development phase was completed, resulting in a producible design which met program goals. This design was subjected to extensive tests to demonstrate performance under a wide variety of conditions. The component was found to perform in a predictable manner. Measured overall component thermal conductance was 4.0 W/cm2/°C for fluxes up to 60 W/cm2.

Simultaneous thermal and hydraulic analysis has been completed using SINDA'85/FLUINT for a two-phase ammonia thermal control system proposed for Space Station Freedom Attached Payload Accommodation Equipment (APAE). This analysis provided information on system performance, transient behavior during heat load changes, and control system response. Control system logic and non-equilibrium effects were included in the model. This paper describes the hardware used in this thermal control system and the modelling techniques used to represent it. A brief comparison of the predicted system performance with test results from ground testing of similar systems at NASA Johnson Space Center is also provided.

Discussed are some critical theoretical and experimental research issues to be investigated for candidate two-phase thermal control systems (and their components), to define what is to be done to develop reliable systems, for near and far future planetary applications envisaged. An earlier publication SAE-2007-01-3242 (“Design of planetary two-phase thermal control systems, using experimental data of terrestrial model systems, built according to thermal-gravitational modelling and scaling laws”), discussed that such advanced thermal control systems are one of the key technologies needed for future applications within the framework of the NASA Authorization Act 2005. This act specifies a programme to be established to develop sustained human presence on the Moon, including a robust pre-curser programme to promote exploration, science, commerce and US preeminence in space, also as a stepping stone to future exploration of Mars and other planetary destinations.

This paper gives a general overview of the objectives of European two-phase heat transport systems as well as of their development status. In particular the actual design of the ESA funded development program “Two-Phase Heat Transport Systems - Critical Components” will be shown. Results are also reported on an extensive program of development of heat absorbing components for an application in two-phase thermal systems sponsored by the German Ministry of Research and Technology. The objectives of this project were to design, manufacture and test three types of evaporators or cold plates, two of them designed for an application in a mechanically pumped loop and one foreseen to operate as evaporative capillary pump in a capillary pumped loop. Finally a short outlook is given on the planned future European two-phase development activities.

Many diesel engines have to work at load profiles which, due to the low exhaust gas temperatures, necessitate active regeneration procedures to ensure continued engine operation and the reliability of the particulate filter. An active regeneration may be initiated via inner engine measures such as late injection. However, due to high maintenance interval and run time requirements for non-road applications the combustion of soot accumulated in the diesel particulate filter (DPF) often is realized via downstream processes. Known methods for this purpose are burner systems, systems based on downstream hydrocarbon injection (HCI) and subsequent hydrocarbon (HC)-conversion due to a catalyst or a combination of both. This paper describes an autarkic system using two-stage electro-thermal-supported hydrocarbon conversion. This system is capable to regenerate a DPF within the entire engine operating range and it is less complex than flame burner systems.