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Modified soldering iron extracts a wrap-around solar cell that is attached with solder or adhesive to a substrate without destroying the cell removed or damaging adjacent cells. Heat, vacuum, and compressed air, operated from a special head attached to the soldering iron, loosen, extract, and protect the cell.
A very low-power, low-interference Stirling cryocooler is being developed based on principles and techniques described in several previous publications over the last four years. It differs in several important details from those built previously. It uses a tapered displacer based upon an analytical optimization procedure. The displacer is driven by an auxiliary piston and cylinder (rather than by mechanical linkage) using some of the working fluid itself to provide the driving force. This provides smooth, vibration-free motion, and, more importantly, allows complete mechanical and spatial separation of the cryostat from the pressure-wave generator. Either of two different pressure-wave generators can be used. One is a non-contaminating, unlubricated ceramic piston and cylinder. The other is a compressed-air-operated rubber diaphragm with motor-driven valves to cycle the pressure between appropriate limits.
Tool is inexpensive and gives repeatable results. It is modified commercially-available rod-type weld slag removal gun and is pneumatically operated by regulated compressed air supply.
The nozzle acoustic test rig (NATR) was built at NASA Lewis Research Center to support the High Speed Research Program. The facility is capable of measuring the acoustic and aerodynamic performance of aircraft engine nozzle concepts. Trade-off studies are conducted to compare performance and noise during simulated low-speed flight and takeoff. Located inside an acoustically treated dome with a 62-ft radius, the NATR is a free-jet that has a 53-in. diameter and is driven by an air ejector. This ejector is operated with 125 lb/s of compressed air, at 125 psig, to achieve 375 lb/s at Mach 0.3. Acoustic and aerodynamic data are collected from test nozzles mounted in the free-jet flow. The dome serves to protect the surrounding community from high noise levels generated by the nozzles, and to provide an anechoic environment for acoustic measurements. Information presented in this report summarizes free-jet performance, fluid support systems, and data acquisition capabilities of the NATR.
The figure depicts an apparatus for mechanical testing of nuts. In the original application for which the apparatus was developed, the nuts are of a frangible type designed for use with pyrotechnic devices in spacecraft applications in which there are requirements for rapid, one-time separations of structures that are bolted together. The apparatus can also be used to test nonfrangible nuts engaged without pyrotechnic devices. This apparatus was developed to replace prior testing systems that were extremely heavy and immobile and characterized by long setup times (of the order of an hour for each nut to be tested). This apparatus is mobile, and the setup for each test can now be completed in about five minutes. The apparatus can load a nut under test with a static axial force of as much as 6.8 x 10(exp 5) lb (3.0 MN) and a static moment of as much as 8.5 x 10(exp 4) lb in. (9.6 x 10(exp 3) N(raised dot)m) for a predetermined amount of time. In the case of a test of a frangible nut, the pyrotechnic devices can be exploded to break the nut while the load is applied, in which case the breakage of the nut relieves the load. The apparatus can be operated remotely for safety during an explosive test. The load-generating portion of the apparatus is driven by low-pressure compressed air; the remainder of the apparatus is driven by 110-Vac electricity. From its source, the compressed air is fed to the apparatus through a regulator and a manually operated valve. The regulated compressed air is fed to a pneumatically driven hydraulic pump, which pressurizes oil in a hydraulic cylinder, thereby causing a load to be applied via a hydraulic nut (not to be confused with the nut under test). During operation, the hydraulic pressure is correlated with the applied axial load, which is verified by use of a load cell. Prior to operation, one end of a test stud (which could be an ordinary threaded rod or bolt) is installed in the hydraulic nut. The other end of the test stud passes through a bearing plate; a load cell is slid onto that end, and then the nut to be tested is threaded onto that end and tightened until the nut and load cell press gently against the bearing plate.
The computer program described in this report calculates the design-point characteristics of a compressed-air generator for use in V/STOL applications such as systems with a tip-turbine-driven lift fan. The program computes the dimensions and mass, as well as the thermodynamic performance of a model air generator configuration which involves a straight through-flow combustor. Physical and thermodynamic characteristics of the air generator components are also given. The program was written in FORTRAN IV language. Provision has been made so that the program will accept input values in either SI units or U.S. customary units. Each air generator design-point calculation requires about 1.5 seconds of 7094 computer time for execution.
Engine test results are presented for simulated altitude conditions. A displaced-piston combustion chamber on a 5- by 7-inch single cylinder compression-ignition engine operating at 2,000 r.p.m. was used. Inlet air temperature equivalent to standard altitudes up to 14,000 feet were obtained. Comparison between performance at altitude of the unsupercharged compression-ignition engine compared favorably with the carburetor engine. Analysis of the results for which the inlet air temperature, inlet air pressure, and inlet and exhaust pressure were varied indicates that engine performance cannot be reliably corrected on the basis of inlet air density or weight of air charge. Engine power increases with inlet air pressure and decreases with inlet air temperatures very nearly as straight line relations over a wide range of air-fuel ratios. Correction factors are given.
A rugged and compact fiber optic sensor system for in situ real-time measurement of nitrogen (N2), oxygen (O2), hydrocarbon (HC) fuel vapors, and other gases has been developed over the past several years at Glenn Research Center. The intrinsically-safe, solid-state fiber optic sensor system provides a 1% precision measurement (by volume) of multiple gases in a 5-sec time window. The sensor has no consumable parts to wear out and requires less than 25 W of electrical power to operate. The sensor head is rugged and compact and is ideal for use in harsh environments such as inside an aircraft fuel tank, or as a feedback sensor in the vent-box of an on-board inert gas generation system (OBIGGS). Multiple sensor heads can be monitored with a single optical detection unit for a cost-effective multi-point sensor system. The present sensor technology is unique in its ability to measure N2 concentration directly, and in its ability to differentiate different types of HC fuels. The present sensor system provides value-added aircraft safety information by simultaneously and directly measuring the nitrogen-oxygen-fuel triplet, which provides the following advantages: (1) information regarding the extent of inerting by N2, (2) information regarding the chemical equivalence ratio, (3) information regarding the composition of the aircraft fuel, and (4) by providing a self-consistent calibration by utilizing a singular sensor for all species. Using the extra information made available by this sensor permits the ignitability of a fuel-oxidizer mixture to be more accurately characterized, which may permit a reduction in the amount of inerting required on a real-time basis, and yet still maintain a fire-safe fuel tank. This translates to an increase in fuel tank fire-safety through a better understanding of the physics of fuel ignition, and at the same time, a reduction in compressed bleed air usage and concomitant aircraft operational costs over the long-run. The present fiber optic sensor can also be used as a false-alarm-free engine/hidden/cargo space fire detector (by measuring increased CO2 and CO, and decreased O2), a multi-point in situ measurement and certification system for halogenated-compound fire protection systems, and for the testing and certification of other aircraft safety sensor systems. The technology (LEW-17826-1) developed in the present sensor system is patent pending.
Spike diffusers are presented as a means to improve supersonic ejector efficiency via reduction in shock losses. Design, fabrication, and testing of an articulated prototype is described. Experimental results are compared to empirical performance curves representing the loci of optimal one- and two-stage conventional ejectors driven by dry air and discharging to atmosphere. Operated at a compression ratio of ~10 with all inputs equal, the spike ejector is shown to have achieved up to 2.19X and 1.83X the secondary mass throughput of the one- and two-stage references, respectively. This suggests the potential of spike diffusers to reduce ejector operating costs by ~50%.
Stable operating range of supersonic mixed compression inlet increase by air flow removal via throat bleed system
The feasibility of the generation of detonation waves moving periodically across high speed channel flow is experimentally demonstrated. Such waves are essential to the concept of compressing requirements and increasing the engine pressure compressor with the objective of reducing conventional compressor requirements and increasing the engine thermodynamic efficiency through isochoric energy addition. By generating transient transverse waves, rather than standing waves, shock wave losses are reduced by an order of magnitude. The ultimate objective is to use such detonation ducts downstream of a low pressure gas turbine compressor to produce a high overall pressure ratio thermodynamic cycle. A 4 foot long, 1 inch x 12 inch cross-section, detonation duct was operated in a blow-down mode using compressed air reservoirs. Liquid or vapor propane was injected through injectors or solenoid valves located in the plenum or the duct itself. Detonation waves were generated when the mixture was ignited by a row of spark plugs in the duct wall. Problems with fuel injection and mixing limited the air speeds to about Mach 0.5, frequencies to below 10 Hz, and measured pressure ratios of about 5 to 6. The feasibility of the gas dynamic compression was demonstrated and the critical problem areas were identified.
A knock-limited performance investigation was conducted on blends of triptane and 28-P fuel with a 12-cylinder, V-type, liquid-cooled aircraft engine of 1710-cubic-inch displacement at three compression ratios: 6.65, 7.93, and 9.68. At each compression ratio, the effect of changes in temperature of the inlet air to the auxiliary-stage supercharger and in fuel-air ratio were investigated at engine speeds of 2280 and. 3000 rpm. The results show that knock-limited engine performance, as improved by the use of triptane, allowed operation at both take-off and cruising power at a compression ratio of 9.68. At an inlet-air temperature of 60 deg F, an engine speed of 3000 rpm ; and a fuel-air ratio of 0,095 (approximately take-off conditions), a knock-limited engine output of 1500 brake horsepower was possible with 100-percent 28-R fuel at a compression ratio of 6.65; 20-percent triptane was required for the same power output at a compression ratio of 7.93, and 75 percent at a compression ratio of 9.68 allowed an output of 1480 brake horsepower. Knock-limited power output was more sensitive to changes in fuel-air ratio as the engine speed was increased from 2280 to 3000 rpm, as the compression ratio is raised from 6.65 to 9.68, or as the inlet-air temperature is raised from 0 deg to 120 deg F.
Hedland Flow Meters manufactures a complete line of flow meters used in industrial operations to monitor the flow of oil, water or other liquids, air and other compressed gases, including caustics or corrosive liquids/gases. The company produces more than 1,000 types of flow meters featuring rugged construction, simplicity of installation and the ability to operate in any position.
This center operates a number of sophisticated wind tunnels in order to fulfill the needs of its researchers. Compressed air, which is kept in steel storage vessels, is used to power many of these tunnels. Some of these vessels have been in use for many years, and Langley is currently recertifying these vessels to insure their continued structural integrity. One of the first facilities to be recertified under this program was the Langley 8-foot high-temperature structures tunnel. This recertification involved (1) modification, hydrotesting, and inspection of the vessels; (2) repair of all relevant defects; (3) comparison of the original design of the vessel with the current design criteria of Section 8, Division 2, of the 1974 ASME Boiler and Pressure Vessel Code; (4) fracture-mechanics, thermal, and wind-induced vibration analyses of the vessels; and (5) development of operating envelopes and a future inspection plan for the vessels. Following these modifications, analyses, and tests, the vessels were recertified for operation at full design pressure (41.4 MPa (6000 psi)) within the operating envelope developed.
Recent progress in an evaluation of the applicability of the hydrogen enrichment concept to achieve ultralow gaseous pollutant emission from gas turbine combustion systems is described. The target emission indexes for the program are 1.0 for oxides of nitrogen and carbon monoxide, and 0.5 for unburned hydrocarbons. The basic concept utilizes premixed molecular hydrogen, conventional jet fuel, and air to depress the lean flammability limit of the mixed fuel. This is shown to permit very lean combustion with its low NOx production while simulataneously providing an increased flame stability margin with which to maintain low CO and HC emission. Experimental emission characteristics and selected analytical results are presented for a cylindrical research combustor designed for operation with inlet-air state conditions typical for a 30:1 compression ratio, high bypass ratio, turbofan commercial engine.
KSC has used cryogenic life support (liquid air based) technology successfully for many years to support spaceflight operations. This technology has many benefits unique to cryogenics when compared to traditional compressed gas systems: passive cooling, lighter, longer duration, and lower operating pressure. However, there are also several limiting factors that have prevented the technology from being commercialized. The National Institute of Occupational Safety and Health, Office of Mine Safety and Health Research (NIOSH-OMSHR) has partnered with NASA to develop a complete liquid air based life support solution for emergency mine escape and rescue. The project will develop and demonstrate various prototype devices and incorporate new technological innovations that have to date prevented commercialization.
Data are presented to show the effects of inlet-air pressure, inlet-air temperature, and compression ratio on the maximum permissible performance obtained with having a hemispherical-dome combustion chamber. The five aircraft-engine fuels used have octane numbers varying from 90 to 100 plus 2 ml of tetraethyl lead per gallon. The data were obtained on a 5 1/4-inch by 4 3/4-inch liquid-cooled engine operating at 2,500 r.p.m. The compression ratio was varied from 6.0 to 8.9. The inlet-air temperature was varied from 110 to 310 F. For each set of conditions, the inlet-air pressure was increased until audible knock occurred and then reduced 2 inches of mercury before data were recorded. The results for each fuel can be correlated by plotting the calculated end-gas density factor against the calculated end-gas temperature. Measurements of spark-plugs, cutting off the switch to one spark plug lowered the electrode temperature of that plug from a value of 1,365 F to a value of 957 F. The results indicate that the surface temperatures of combustion-chamber areas which become new sources of ignition markedly increase after ignition.
Data are presented to show the effects of inlet-air pressure, inlet-air temperature, and compression ratio on the maximum permissible performance obtained on a single-cylinder test engine with aircraft-engine fuels varying from a fuel of 87 octane number to one 100 octane number plus 1 ml of tetraethyl lead per gallon. The data were obtained on a 5-inch by 5.75-inch liquid-cooled engine operating at 2,500 r.p.m. The compression ratio was varied from 6.50 to 8.75. The inlet-air temperature was varied from 120 to 280 F. and the inlet-air pressure from 30 inches of mercury absolute to the highest permissible. The limiting factors for the increase in compression ratio and in inlet-air pressure was the occurrence of either audible or incipient knock. The data are correlated to show that, for any one fuel,there is a definite relationship between the limiting conditions of inlet-air temperature and density at any compression ratio. This relationship is dependent on the combustion-gas temperature and density relationship that causes knock. The report presents a suggested method of rating aircraft-engine fuels based on this relationship. It is concluded that aircraft-engine fuels cannot be satisfactorily rated by any single factor, such as octane number, highest useful compression ratio, or allowable boost pressure. The fuels should be rated by a curve that expresses the limitations of the fuel over a variety of engine conditions.