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At least 1,387 records · Page 77

Analysis of several methods of pumping cooling air for turbojet engine afterburners

Several methods of pumping air to an annular cooling passage surrounding a typical axial-flow turbojet-engine afterburner were evaluated and compared on the basis of thrust and specific fuel consumption of the systems. Each system was analyzed over a range of afterburner-wall temperatures, flight Mach numbers, and exhaust-gas temperatures at sea level and 35,000 feet. Ram pressure recovery, boundary-layer pressure recovery, and the engine-jet actuated ejector appear to be satisfactory systems at high Mach numbers. Cooling with compressor-exit air bleed was found to be unsatisfactory,but the use of compressor-exit bleed air as the primary fluid in a high-performance ejector was satisfactory. The use of an auxiliary compressor driven from the engine shaft increased the thrust and decreased the specific fuel consumption of the engine for many of the conditions investigated.

PUMPS, JET AND THRUST AUGMENTORS↗

Mars Pathfinder mechanically pumped cooling loop

A mechanically pumped single-phase cooling loop was successfully flown on the Mars Pathfinder (MPF) Spacecraft which safely landed on the Martian surface on July 4, 1997. One of the key technologies that enabled the mission to succeed was an active heat rejection system (HRS) used to cool the electronics on the spacecraft during its seven-month cruise from Earth to Mars.

spacecraft tehermal control pumped cooling loop↗

Pumped Fluid Loop Heat Rejection and Recovery Systems for Thermal Control of the Mars Science Laboratory

This viewgraph presentation reviews the heat rejection and heat recovery system for thermal control of the Mars Science Laboratory (MSL). The MSL mission will use mechanically pumped fluid loop based architecture for thermal control of the spacecraft and rover. The architecture is designed to harness waste heat from an Multi Mission Radioisotope Thermo-electric Generator (MMRTG) during Mars surface operations for thermal control during cold conditions and also reject heat during the cruise aspect of the mission. There are several test that are being conducted that will insure the safety of this concept. This architecture can be used during any future interplanetary missions utilizing radioisotope power systems for power generation.

mechanical pump fluid loop↗

Mars Science Laboratory Rover Integrated Pump Assembly Bellows Jamming Failure

The Mars Science Laboratory rover and spacecraft utilize two mechanically pumped fluid loops for heat transfer to and from the internal electronics assemblies and the Radioisotope Thermo-Electric Generator (RTG). The heat transfer fluid is Freon R-11 (CFC-11) which has a large coefficient of thermal expansion. The Freon within the heat transfer system must have a volume for safe expansion of the fluid as the system temperature rises. The device used for this function is a gas-over-liquid accumulator. The accumulator uses a metal bellows to separate the fluid and gas sections. During expansion and contraction of the fluid in the system, the bellows extends and retracts to provide the needed volume change. During final testing of a spare unit, the bellows would not extend the full distance required to provide the needed expansion volume. Increasing the fluid pressure did not loosen the jammed bellows either. No amount of stroking the bellows back and forth would get it to pass the jamming point. This type of failure, if it occurred during flight, would result in significant overpressure of the heat transfer system leading to a burst failure at some point in the system piping. A loss of the Freon fluid would soon result in a loss of the mission. The determination of the source of the jamming of the bellows was quite elusive, leading to an extensive series of tests and analyses. The testing and analyses did indicate the root cause of the failure, qualitatively. The results did not provide a set of dimensional limits for the existing hardware design that would guarantee proper operation of the accumulator. In the end, a new design was developed that relied on good engineering judgment combined with the test results to select a reliable enough solution that still met other physical constraints of the hardware, the schedule, and the rover system.

bellows↗

Performance of the Mechanically Pumped Fluid Loop Rover Heat Rejection System Used for Thermal Control of the Mars Science Laboratory Curiosity Rover on the Surface of Mars

The challenging range of landing sites for which the Mars Science Laboratory Rover was designed, required a rover thermal management system that is capable of keeping temperatures controlled across a wide variety of environmental conditions. On the Martian surface where temperatures can be as cold as -123 C and as warm as 38 C, the Rover relies upon a Mechanically Pumped Fluid Loop (MPFL) Rover Heat Rejection System (RHRS) and external radiators to maintain the temperature of sensitive electronics and science instruments within a -40 C to +50 C range. The RHRS harnesses some of the waste heat generated from the Rover power source, known as the Multi Mission Radioisotope Thermoelectric Generator (MMRTG), for use as survival heat for the rover during cold conditions. The MMRTG produces 110 Watts of electrical power while generating waste heat equivalent to approximately 2000 Watts. Heat exchanger plates (hot plates) positioned close to the MMRTG pick up this survival heat from it by radiative heat transfer and supply it to the rover. This design is the first instance of use of a RHRS for thermal control of a rover or lander on the surface of a planet. After an extremely successful landing on Mars (August 5), the rover and the RHRS have performed flawlessly for close to an earth year (half the nominal mission life). This paper will share the performance of the RHRS on the Martian surface as well as compare it to its predictions.

Mars↗

Grid Integration and Market Analysis of Adjustable-Speed Pumped Storage Hydropower

Variable renewable energy is increasing, affecting variability and range of energy prices and requiring extra power system flexibility. Adjustable-speed pumped storage hydropower (AS-PSH), can provide value to ancillary service markets and take benefit of energy arbitrage. Present results from production cost models showing the effects of adding 50 MW of AS-PSH to three Independent System Operators (ISOs).

24 POWER TRANSMISSION AND DISTRIBUTION↗