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Pneumatic analog-to-pulse frequency converter circuit has output pulse frequency proportional to the pressure level of the input signal. Converter circuit drives a pneumatic stepping motor and is part of a pneumatic control system for nuclear powered spacecraft.
Data on experimental verification of Iberall's analysis applies to such problems as pressure sensing, pneumatic control circuits with bellows, measuring irregular shaped volumes, and transmitting fluid power by pulsating flow.
Technology developed for the Circulation Control Wing high-lift system has been extended to augment lift by entraining and redirecting engine thrust. Ejecting a thin jet sheet tangentially over a small curved deflecting surface adjacent to the slipstream of a turbofan engine causes the slipstream to flow around that deflecting surface. The angle of deflection is controlled pneumatically by varying the momentum of the thin jet sheet. The downward momentum of the slipstream enhances wing lift. This concept of pneumatically deflecting the slipstream has been applied to an upper surface blowing high-lift system and to a thrust deflecting system. The capability of the pneumatic upper surface blowing system was demonstrated in a series of investigations using a wind tunnel model and the NASA Quiet Short-haul Research Aircraft (QSRA). Full-scale thrust deflections greater than 90 deg were achieved. This mechanically simple system can provide increased maneuverability, heavy lift or overload capability, or short takeoff and landing performance.
Efficacy of existing on-board propulsion systems health management systems (HMS) are severely impacted by computational limitations (e.g., low sampling rates); paradigmatic limitations (e.g., low-fidelity logic/parameter redlining only, false alarms due to noisy/corrupted sensor signatures, preprogrammed diagnostics only); and telemetry bandwidth limitations on space/ground interactions. Ultra-compact/light, adaptive neural networks with massively parallel, asynchronous, fast reconfigurable and fault-tolerant information processing properties have already demonstrated significant potential for inflight diagnostic analyses and resource allocation with reduced ground dependence. In particular, they can automatically exploit correlation effects across multiple sensor streams (plume analyzer, flow meters, vibration detectors, etc.) so as to detect anomaly signatures that cannot be determined from the exploitation of single sensor. Furthermore, neural networks have already demonstrated the potential for impacting real-time fault recovery in vehicle subsystems by adaptively regulating combustion mixture/power subsystems and optimizing resource utilization under degraded conditions. A class of high-performance neuroprocessors, developed at JPL, that have demonstrated potential for next-generation HMS for a family of space transportation vehicles envisioned for the next few decades, including HLLV, NLS, and space shuttle is presented. Of fundamental interest are intelligent neuroprocessors for real-time plume analysis, optimizing combustion mixture-ratio, and feedback to hydraulic, pneumatic control systems. This class includes concurrently asynchronous reprogrammable, nonvolatile, analog neural processors with high speed, high bandwidth electronic/optical I/O interfaced, with special emphasis on NASA's unique requirements in terms of performance, reliability, ultra-high density ultra-compactness, ultra-light weight devices, radiation hardened devices, power stringency, and long life terms.
As an alternative to conventional tubing instrumentation for measuring airflow, designers and technicians at the NASA Glenn Research Center have been fabricating packaging components and assembling a set of unique probes using commercial-off-the-shelf microelectromechanical systems (MEMS) integrated circuits (computer chips). Using MEMS as an alternative has some compelling advantages over standard measurement devices. Sensor technologies have matured through high-production usage in industries such as automotive and aircraft manufacturers. Currently, MEMS are the choice in applications such as tire pressure monitors, altimeters, pneumatic controls, cable leak detectors, and consumer appliances. Conventional instrumentation uses tubing buried in the model aerodynamic surfaces or wind tunnel walls. The measurements are made when pressure is introduced at the tube opening. The pressure then must travel the tubing for lengths ranging from 20 to hundreds of feet before reaching an electronic signal conditioner. This condition causes a considerable amount of damping and requires measurements to be made only after the test rig has reached steady-state operation. The electronic MEMS pressure sensor is able to take readings continuously under dynamic states in nearly real time. The use of stainless steel tubing for pressure measurements requires many tubes to be cleaned, cut to length, carefully installed, and delicately deburred and spliced for use. A cluster of a few hundred 1/16-in.- (0.0625-in.-) diameter tubes (not uncommon in research testing facilities) can be several inches in diameter and may weigh enough to require two men to handle. Replacing hard tubing with electronic chips can eliminate much of the bulk. Each sensor would fit on the tip of the 1/16-in. tubing with room to spare. The P592 piezoresistive silicon pressure sensor (Lucas NovaSensor, Fremont, CA) was chosen for this project because of its cost, availability, and tolerance to extreme ambient conditions. The chip is 1 mm square by 0.6 mm thick (0.039 by 0.023 in.) with 0.12-mm (0.005-in.) wire connection tabs. Three MEMS chips were used to build the first type of flow-angularity probe. This MEMS probe will be demonstrated as an alternative to a standard tube type "Cobra Probe" now used routinely in wind tunnel and aeronautical hardware applications. The response time and accuracy would allow the probe to be translated on an actuator across a flow field, yielding precision dynamic measurements not possible with conventional instrumentation. The low profile, the minimal power requirement, the rugged construction, and the moderate cost all contribute to making MEMS sensors the enticing choice instrument in future research measurement needs. The MEMS probe efforts are a continuation of work initiated by Brian Willis, without whose foresight and efforts this project would never have been realized. This task was funded through cooperation with the NASA Electronic Parts and Packaging (NEPP) program at the Jet Propulsion Laboratory.
As an alternative to conventional tubing instrumentation for measuring airflow, designers and technicians at Glenn Research Center have been fabricating packaging components and assembling a set of unique probes that contain commercial off-the-shelf (COTS) microelectromechanical systems (MEMS) sensor chips. MEMS sensor chips offer some compelling advantages over standard macroscopic measurement devices. MEMS sensor technology has matured through mass production and use in the automotive and aircraft industries. At present, MEMS are the devices of choice for sensors in such applications as tire-pressure monitors, altimeters, pneumatic controls, cable leak detectors, and consumer appliances. Compactness, minimality of power demand, rugged construction, and moderate cost all contribute to making MEMS sensors attractive for instrumentation for future research. Conventional macroscopic flow-measurement instrumentation includes tubes buried beneath the aerodynamic surfaces of wind-tunnel models or in wind-tunnel walls. Pressure is introduced at the opening of each such tube. The pressure must then travel along the tube before reaching a transducer that generates an electronic signal. The lengths of such tubes typically range from 20 ft (approx.= 6 m) to hundreds of feet (of the order of 100 m). The propagation of pressure signals in the tubes damps the signals considerably and makes it necessary to delay measurements until after test rigs have reached steady-state operation. In contrast, a MEMS pressure sensor that generates electronic output can take readings continuously under dynamic conditions in nearly real time. In order to use stainless-steel tubing for pressure measurements, it is necessary to clean many tubes, cut them to length, carefully install them, delicately deburr them, and splice them. A cluster of a few hundred 1/16-in.- (approx.=1.6-mm-) diameter tubes (such clusters are common in research testing facilities) can be several inches (of the order of 10 cm) in diameter and could weigh enough that two technicians are needed to handle it. Replacing hard tubing with electronic chips can eliminate much of the bulk. Each sensor would fit on the tip of a 1/16-in. tube with room to spare. The Lucas NovaSensor P592 piezoresistive silicon pressure sensor was chosen for this project because of its cost, availability, and tolerance to extreme ambient conditions. The sensor chip is 1 mm square by 0.6 mm thick (about 0.039 by 0.039 by 0.024 in.) and includes 0.12-mm (approx.=0.005-in.) wire connection tabs. The figure shows a flow-angularity probe that was built by use of three such MEMS chips. It is planned to demonstrate this MEMS probe as an alternative to a standard tube-type "Cobra" probe now used routinely in wind tunnels and aeronautical hardware. This MEMS probe could be translated across a flow field by use of a suitable actuator, so that its accuracy and the shortness of its response time could be exploited to obtain precise dynamic measurements of a sort that cannot be made by use of conventional tubing-based instrumentation.
Since the turn of the millennium, the United States (U.S.) oil and natural gas (ONG) industry has nearly doubled its natural gas production rate. As a result, the ONG industry has recently come under increasing scrutiny for its contributions to greenhouse gas (GHG) emissions. Consequently, various solutions to this problem have been proposed and formulated to reduce the impacts of GHG emissions on the environment. West Virginia University (WVU) have found it important to research the impacts of recovering vented gas streams into prime-mover engines. The U.S. Department of Energy (DOE) and National Energy Technology Laboratory (NETL) have granted WVU funding to research and develop a “Methane Mitigator” (M2) - a “Scalable Vent Mitigation Strategy to Simultaneously Reduce Methane Emissions and Fuel Consumption from the Compression Industry.” One of the main areas of interest for this research was the collection of emissions from natural gas equipment into a Caterpillar G3508J natural gas compression engine. The parameters being analyzed from the engine were brake-specific emissions and power output. The emissions sources considered for this research were pneumatic controllers (PCs), reciprocating compressor vents, and the engine’s open crankcase breather. The compressor vent and PC emissions were simulated using a mass flow controller (MFC) and flowed into the engine using two separate methods: (1) directly into the air intake, and (2) through a retrofitted closed crankcase ventilation system (CCV), serving as a buffer volume. The crankcase emissions were quantified without the CCV, and the impact on exhaust emissions from circulating the crankcase gases into the intake was measured. The simulated compressor vent and PC flows from the MFC had limited effect on the steady state operation of the engine and resulting performance. When the simulated flows were fed directly into the engine’s air intake, the changes within the engine’s continuous performance and emission parameters were larger but lasted for shorter durations. Conversely, when the simulated flows were fed into the CCV before entering the air intake, the changes in the engine’s performance and emission parameters were less pronounced for continuous analysis but lasted for longer durations. In either case, the continuous emission changes in both emissions and performance varied in size depending on the test scenario being run, but the cycle average changes in emissions and performance showed little impact overall compared to the engine’s baseline operation. As a result, the inclusion of a CCV shows a decrease in baseline carbon dioxide equivalent (CO2-eq.) engine emissions (from combined exhaust and open crankcase) of almost 4%. Likewise, the CCV inclusion reduced baseline total methane (CH4) from combined exhaust and open crankcase by upwards of 16%. These atmospheric emissions only decreased further with the inclusions of collected PC and compressor vent flows. The resulting changes in time-averaged rated exhaust behavior (or lack thereof) prove that the proposed M2 system could likely be deployed at sites with modern lean-burn natural gas engines as a viable option for reducing and eliminating potential GHG sources that would have otherwise been unutilized as energy sources.
A full aircraft geometry is used to computationally analyze the effectiveness of a pneumatic forebody flow control concept. An overset grid technique is employed to model the aircraft and slot geometry. Steady-state solutions for both isolated forebody and full aircraft configurations are carried out using a thin-layer Navier-Stokes flow solver. A solution obtained using the full aircraft geometry and a flight sideslip condition investigates the effect of sideslip on the leading edge extention vortex burst point. A no-sideslip blowing solution using the isolated forebody at full-scale wind tunnel test conditions is compared with experimental data to determine the accuracy of the numerical method. A solution employing the full geometry and slot blowing at flight conditions is obtained.
Pneumatic and hydraulic fluidic power control systems, discussing moving part position servos and cold gas reaction systems
The concept of the lateralizer device is to sense the difference in wing tip static pressures (differential pressures being created by wing tip venturis) produced when any deviation from straight to level flight occurs. In a steady state turn the low slow wing tip experiences less venturi suction than the high fast wing tip. This signal activates the appropriate servos connected to the ailerons to produce a wing leveling restoring moment. If the wing is subjected to rolling velocities due to changes of the local angle of attack at the tip, the downgoing wing tip operates at a higher angle than the upgoing one. If with an increase in the angle of attack the signal is such that it increases the venturi pressure, then the servos are activated to produce the most negative signal to an upgoing aileron which results in a wing leveling restoring moment. In other words, any deviation from straight and level flight in either roll or yaw is exploited and the difference signal from the differential pressures activates the servo to effect or produce the necessary corrective action to null the signal.
The injection of thin, high-momentum jets of air into the fuselage forebody boundary layers of the F-18 aircraft is explored numerically as a means of controlling the onset of fuselage vortices and of generating yaw control forces. The study was carried out for an angle of attack of 30 deg with symmetrical and asymmetrical blowing configurations. One-sided blowing results in a strongly asymmetrical flow pattern in the fore portion of the fuselage, leading to a net lateral force.
Aerodynamic control using pneumatic forebody flow control was studied. Three methods of control were investigated: (1) blowing from a localized jet, (2) blowing from a slot, and (3) surface suction. Flow visualization and yawing moment measurements were performed on F/A-18 models in a water tunnel. The results show that all the methods were effective in controlling the forebody flow over a wide range of angles of attack and sideslip. The advantages and limitations of each of the control methods were discussed. The experiments suggested that all the control methods work basically on the principle of separation control. Based on the results of the water tunnel tests, the blowing or suction mass flow requirements appear to be within the limits of typical engine-bleed available from a modern fighter engine.
The effectiveness of a tangential slot blowing concept for generating lateral control forces on an aircraft forebody is analyzed using computational fluid dynamics. The flow about a fighter forebody is computed using a multiple-zone, thin-layer Navier-Stokes code. Tangential slot blowing is modeled by the use of an actuator plane. The effects of slot location and slot length on the efficiency of the system are analyzed. Results of the study indicate that placement of the slot near the nose of the aircraft greatly enhances the efficiency of the system, while the length and circumferential location of the slot are of secondary importance. Efficiency is defined by the amount of side force or yawing moment obtained per unit blowing coefficient. The effect of sideslip on the system is also analyzed. The system is able to generate incremental changes in forces and moments in flows with sideslip angles up to 10 deg comparable to those obtained at zero sideslip. These results are used to determine a baseline configuration for an experimental study of the tangential slot blowing concept.
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The following topics are discussed: (1) X-29 description; Vortex Flow Control (VFC) technology description; (3) X-29 VFC wind tunnel results (forebody only); (4) X-29 VFC wind tunnel results (full configuration yawing moment); (5) X-29 VFC wind tunnel results (full configuration C(sub n) with sideslip); (6) X-29VFC wind tunnel results (full configuration pitching moment); (7) VFC optimized nozzle details; (8) X-29 forebody nozzle configuration; (9) X-29 VFC system stored gas schematic; (10) X-29 VFC system stored gas installation; (11) VFC effectiveness at zero sideslip; (12) VFC effectiveness at 35 AOA with sideslip; (13) 'VFC Roll' at 40 AOA; (14) Effects of VFC on wing rock; (15) Integrated controls C(sub n) prediction; (16) Proposed F-15 with lateral control laws with active VFC; (17) Simulated F-15 roll performance with active VFC; (18) Simulated F-15 spin recovery with active VFC; (19) Test team restructuring; (20) testbed selection; (21) Simulation for risk reduction; (22) Benefits of high pressure system; and (23) Advanced weapon system integration.
We explore the feasibility of using nominally-orthogonal jets as active aerodynamic load control for multi-element high-lift systems, and whether the nominally-orthogonal jets can offer a variety of performance improvements. These nominally-orthogonal jets inject momentum normal to the airfoil surface near the flap trailing edge, where they create a vortex that entrains flow from the opposing side and change the airfoil circulation. Lift-enhancement opportunities of trailing edge nominally-orthogonal jets have previously been studied by Malavard et al. and Blaylock et al. on single-element airfoils; however, their effect on drag was not thoroughly investigated. In this study, we investigate two- dimensional nominally-orthogonal jet effects on both lift and drag on a two-element airfoil, NLR7301. We utilize Chimera Grid Tools to generate structured curvilinear overset grids, and the Reynolds-averaged Navier-Stokes solver OVERFLOW-2 to solve for the flow field around the airfoil. We perform various computational sensitivity studies on the baseline airfoil without a jet to validate computational results against benchmark experimental data. Using a Chimera overset grid topology, we demonstrate a similar lift-enhancement effect between a nominally-orthogonal jet and a nominally-orthogonal physical tab employed at the same location on the studied airfoil. After we introduce the nominally-orthogonal jet concept, we investigate nominally-orthogonal jets with various momentum coefficient settings, C(sub µ) = 0.00 − 0.04 and present a lift-enhancement relationship ∆C(sub l) ≃ 3.59 (C(sub µ)) for this airfoil. We discuss that utilizing a nominally-orthogonal jet with C(sub µ) = 0.01 can shift the linear region of the lift curve by a ∆C(sub l) = 0.36 for the pressure side jet and by a ∆C(sub l) = −0.27 for the suction side jet. Employing a nominally-orthogonal jet is also shown effective in altering the drag. To study the impact, we carry out a drag decomposition study in the form of drag polars. We show for a given C(sub l) = 2.50, a nominally-orthogonal jet with C(sub µ) = 0.01 on the pressure and suction side of the airfoil results in 113 drag count decrements and 41 drag count increments, respectively, compared to the baseline airfoil with no jet. These results show that large and controllable changes in aerodynamic performance can be achieved by relatively small active flow control inputs using the nominally-orthogonal jets presented in this study.
Design and performance of a heart assist or artificial heart control system using pneumatic pump systems