Some Parameters Affecting the Performance of Pneumatic Tires on Wet Pavement
Runway condition and tire tread design in relation to pneumatic tire braking and directional control on wet pavement
TIRE↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Welding at the Kennedy Space Center.
Brief description of the nature of the mechanical equipment at a space launch complex from a welding viewpoint. including an identification of the major welding applications used in the construction of this complex. The role played by welding in the ground support equipment is noted, including the welded structures and systems required in the vehicle assembly building, the mobile launchers, transporters, mobile service structure, launch pad and launch site, the propellants system, the pneumatics system, and the environmental control system. The welding processes used at the Kennedy Space Center are reviewed, and a particularly detailed account is given of the design and fabrication of the liquid hydrogen and liquid oxygen storage spheres and piping. Finally, the various methods of testing and inspecting the storage spheres are cited.
Clautice, W. E.↗
System Analyses of Pneumatic Technology for High Speed Civil Transport Aircraft
The primary aspiration of this study was to objectively assess the feasibility of the application of a low speed pneumatic technology, in particular Circulation Control (CC) to an HSCT concept. Circulation Control has been chosen as an enabling technology to be applied on a generic High Speed Civil Transport (HSCT). This technology has been proven for various subsonic vehicles including flight tests on a Navy A-6 and computational application on a Boeing 737. Yet, CC has not been widely accepted for general commercial fixed-wing use but its potential has been extensively investigated for decades in wind tunnels across the globe for application to rotorcraft. More recently, an experimental investigation was performed at Georgia Tech Research Institute (GTRI) with application to an HSCT-type configuration. The data from those experiments was to be applied to a full-scale vehicle to assess the impact from a system level point of view. Hence, this study attempted to quantitatively assess the impact of this technology to an HSCT. The study objective was achieved in three primary steps: 1) Defining the need for CC technology; 2) Wind tunnel data reduction; 3) Detailed takeoff/landing performance assessment. Defining the need for the CC technology application to an HSCT encompassed a preliminary system level analysis. This was accomplished through the utilization of recent developments in modern aircraft design theory at Aerospace Systems Design Laboratory (ASDL). These developments include the creation of techniques and methods needed for the identification of technical feasibility show stoppers. These techniques and methods allow the designer to rapidly assess a design space and disciplinary metric enhancements to enlarge or improve the design space. The takeoff and landing field lengths were identified as the concept "show-stoppers". Once the need for CC was established, the actual application of data and trends was assessed. This assessment entailed a reduction of the wind tunnel data from the experiments performed by Mr. Bob Englar at the GTRI. Relevant data was identified and manipulated based on the required format of the analysis tools utilized. Propulsive, aerodynamic, duct sizing, and vehicle sizing investigations were performed and information supplied to a detailed takeoff and landing tool, From the assessments, CC was shown to improve the low speed performance metrics, which were previously not satisfied. An HSCT with CC augmentation does show potential for full-scale application. Yet, an economic assessment of an HSCT with and without CC showed that a moderate penalty was incurred from the increased RDT&E costs associated with developing the CC technology and slight increases in empty weight.
Mavris, Dimitri N.↗
Aeroacoustics of a High Aspect-Ratio Jet
Circulation control wings are a type of pneumatic high-lift device that have been extensively researched as to their aerodynamic benefits. However, there has been little research into the possible airframe noise reduction benefits of a circulation control wing. The key element of noise is the jet noise associated with the jet sheet emitted from the blowing slot. This jet sheet is essentially a high aspect-ratio rectangular jet. Thus, to fully understand the noise of a circulation control wing, the noise of high aspect-ratio rectangular jets must also be understood. A high aspect-ratio nozzle was fabricated to study the general characteristics of high aspect-ratio jets with aspect ratios from 100 to 3000. The jet noise of this nozzle was proportional to the 8" power of the jet velocity. It was also found that the jet noise was proportional to the slot height to the 312 power and slot width to the 1/2 power.
Munro, Scott E.↗
Fluid Dynamics of a High Aspect-Ratio Jet
Circulation control wings are a type of pneumatic high-lift device that have been extensively researched as to their aerodynamic benefits. However, there has been little research into the possible airframe noise reduction benefits of a circulation control wing. The key element of noise is the jet noise associated with the jet sheet emitted from the blowing slot. High aspect-ratio jet acoustic results (aspect-ratios from 100 to 3,000) from a related study showed that the jet noise of this type of jet was proportional to the slot height to the 3/2 power and slot width to the 1/2 power. Fluid dynamic experiments were performed in the present study on the high aspect-ratio nozzle to gain understanding of the flow characteristics in an effort to relate the acoustic results to flow parameters. Single hot-wire experiments indicated that the jet exhaust from the high aspect-ratio nozzle was similar to a 2-d turbulent jet. Two-wire space-correlation measurements were performed to attempt to find a relationship between the slot height of the jet and the length-scale of the flow noise generating turbulence structure. The turbulent eddy convection velocity was also calculated, and was found to vary with the local centerline velocity, and also as a function of the frequency of the eddy.
Munro, Scott E.↗
Development of a Prediction Scheme for High Aspect-Ratio Jet Noise
Circulation control wings are a type of pneumatic high-lift device that have been extensively researched as to their aerodynamic benefits. However, there has been little research into the possible airframe noise reduction benefits of a circulation control wing. The key element of noise is the jet noise associated with the jet sheet emitted from the blowing slot. This jet sheet is essentially a high aspect-ratio rectangular jet. A recent study on high aspect-ratio jet noise was performed on a nozzle with aspect-ratios ranging from 100 to 3,000. In addition to the acoustic data, fluid dynamic measurements were made as well. This paper uses the results of these two studies and attempts to develop a prediction scheme for high aspect-ratio jet noise
Munro, Scott E.↗
Pneumatic artificial heart driving system providing quasi-steady-state regulation and pressure waveform control
Design and characteristics of artificial heart control system
Crosby, M. J.↗
Scoping of an Air Supply Configuration for AFC on a Commercial Transport Airplane High Lift System
A scoping study is being conducted on the air supply for a microjet-based active flow control (AFC) system on a twin-turbofan commercial transport airplane. Microjets provide circulation control using small surface-normal pneumatic jets located near the trailing edge of a lifting surface such as a wing or flap. When located on the pressure side of the lifting surface they increase the lift, and when located on the suction side they decrease lift. In this study, microjets are considered for installation in the flaps of the high-lift version of the Common Research Model (CRM-HL). An air supply system involving bleed air from the airplane’s auxiliary power unit (APU) plus ram air provides the air to the microjets. A model based on the 1D compressible flow equations is applied to analyze the air supply system configuration and predict the microjet flow rate with the resulting airplane performance changes based on Reynolds-averaged Navier-Stokes modeling of microjets on the CRM-HL. The results of this scoping study are encouraging in that APU air can be used to entrain ram air and thereby increase the AFC mass flow rate to achieve effective lift control and airplane performance enhancement during takeoff and landing.
AATT↗
Scoping of an Air Supply Configuration for AFC on a Commercial Transport Airplane High Lift System
A scoping study is being conducted on the air supply fora microjet-based active flow control (AFC) system on a twin-turbofan commercial transport airplane. Microjets provide circulation control using small surface-normal pneumatic jets located near the trailing edge of a lifting surface such as a wing or flap. When located on the pressure side of the lifting surface they increase the lift, and when located on the suction side they decrease lift. In this study, microjets are considered for installation in the flaps of the high-lift version of the Common ResearchModel (CRM-HL). Two different architectures to supply the air for the microjets are considered: (1) bleed air from the airplane’s auxiliary power unit (APU) plus ram air, and (2) engine fan bleed air plus ram air. A model based on the 1D compressible flow equations is applied to analyze the air supply system architectures and predict the microjet flow rate with the resulting airplane performance changes based on Reynolds-averaged Navier-Stokes modeling of microjets on the CRM-HL. The results of this scoping study are encouraging in that pressurized air from the APU or the engine fan can be used to entrain ram air and thereby increase the AFC mass flow rate to achieve effective lift control and airplane performance enhancement during takeoff and landing.
AATT↗
Underwater space suit pressure control regulator
A device is reported for regulating the pneumatic pressure in a ventilated space suit relative to the pressure imposed on the suit when being worn by a person underwater to simulate space environment for testing and experimentation. A box unit located on the chest area of the suit comprises connections for suit air supply and return lines and carries a regulator valve that stabilizes the air pressure differential between the inside and outside of the suit. The valve and suit pressure is controlled by the suit occupant and the valve includes a mechanism for quickly dumping the suit pressure in case of emergency. Pressure monitoring and relief devices are also included in the box unit.
Aldrich, B. R.↗
Overview and Assessment of the ESM Pressure Control Performance on Artemis I
The European Service Module propulsion system is a bipropellant hypergolic serial system used to provide translational thrust and attitude control for Orion. To control propellant tank pressure, a bang-bang pressure control system is employed. Each propellant commodity is regulated by a pressure control assembly consisting of two pressurization branches (a primary and redundant pressurization path) where each branch includes 3 valves in series. Regulation is accomplished via flight software control of two downstream solenoid valves triggered off propellant tank ullage pressure. This paper presents an overview of system level challenges which have been overcome to enable a successful Artemis I flight. Principle among the challenges was valve-to-valve pneumatic interactions which drove changes to the control scheme. During the Artemis I mission, the pressure control assembly was able to control tank pressure within allowable tolerances. Comparison between flight data and mathematical models are presented showing excellent agreement. Finally, during flight, a pressure surge was observed during the first regulation cycle when there was propellant in the upstream propellant tank. This was attributed to a gas hammer effect within the pressurization system and was not observable in a 1g environment. This paper also discusses the conclusion that this gas hammer effect is a nominal feature of the system during operations. Assessment of the in-flight performance of the electronic pressure regulation scheme on the European Service Module propulsion system shows the system behaved nominally during the Artemis I mission.
propulsion system↗
Overview and Assessment of the ESM Pressure Control Performance on Artemis I
The European Service Module propulsion system is a bipropellant hypergolic serial system used to provide translational thrust and attitude control for Orion. To control propellant tank pressure, a bang-bang pressure control system is employed. Each propellant commodity is regulated by a pressure control assembly consisting of two pressurization branches (a primary and redundant pressurization path) where each branch includes 3 valves in series. Regulation is accomplished via flight software control of two downstream solenoid valves triggered off propellant tank ullage pressure. This paper presents an overview of system level challenges which have been overcome to enable a successful Artemis I flight. Principle among the challenges was valve-to-valve pneumatic interactions which drove changes to the control scheme. During the Artemis I mission, the pressure control assembly was able to control tank pressure within allowable tolerances. Comparison between flight data and mathematical models are presented showing excellent agreement. Finally, during flight, a pressure surge was observed during the first regulation cycle when there was propellant in the upstream propellant tank. This was attributed to a gas hammer effect within the pressurization system and was not observable in a 1g environment. This paper also discusses the conclusion that this gas hammer effect is a nominal feature of the system during operations. Assessment of the in-flight performance of the electronic pressure regulation scheme on the European Service Module propulsion system shows the system behaved nominally during the Artemis I mission.
propulsion system↗
Spool valve cycles at controlled frequency
Spool valve accurately controls the cycle of a pneumatically-actuated system over long periods. Regulation of pressure from the external source, positioning of the adjusting plugs, and magnet selection, together afford wide variation in cyclic timing and speed of closure in either direction.
Charlton, K. W.↗
A description of model 3B of the multipurpose ventricular actuating system
The multipurpose ventricular actuating system is a pneumatic signal generating device that provides controlled driving pressures for actuating pulsatile blood pumps. Overall system capabilities, the timing circuitry, and calibration instruction are included.
Webb, J. A., Jr.↗
Pneumatic servomechanisms
Dynamic analysis computer program analyzes pneumatic servomechanism and the system it controls. System and device to be modeled can contain up to twenty ullage chambers, twenty moving parts, and forty flow lines. Program is easily modified to model larger systems.
Bailey, T. E.↗
Human Research Program Advanced Exercise Concepts (AEC) Overview
Exercise countermeasures provide benefits that are crucial for successful human spaceflight, to mitigate the spaceflight physiological deconditioning which occurs during exposure to microgravity. The NASA Human Research Program (HRP) within the Human Exploration and Operations Mission Directorate (HEOMD) is managing next generation Advanced Exercise Concepts (AEC) requirements development and candidate technology maturation to Technology Readiness Level (TRL) 7 (ground prototyping and flight demonstration) for all exploration mission profiles from Multi Purpose Crew Vehicle (MPCV) Exploration Missions (up to 21 day duration) to Mars Transit (up to 1000 day duration) missions. These validated and optimized exercise countermeasures systems will be provided to the ISS Program and MPCV Program for subsequent flight development and operations. The International Space Station (ISS) currently has three major pieces of operational exercise countermeasures hardware: the Advanced Resistive Exercise Device (ARED), the second-generation (T2) treadmill, and the cycle ergometer with vibration isolation system (CEVIS). This suite of exercise countermeasures hardware serves as a benchmark and is a vast improvement over previous generations of countermeasures hardware, providing both aerobic and resistive exercise for the crew. However, vehicle and resource constraints for future exploration missions beyond low Earth orbit will require that the exercise countermeasures hardware mass, volume, and power be minimized, while preserving the current ISS capabilities or even enhancing these exercise capabilities directed at mission specific physiological functional performance and medical standards requirements. Further, mission-specific considerations such as preservation of sensorimotor function, autonomous and adaptable operation, integration with medical data systems, rehabilitation, and in-flight monitoring and feedback are being developed for integration with the exercise countermeasures systems. Numerous technologies have been considered and evaluated against HRP-approved functional device requirements for these extreme mission profiles, and include wearable sensors, exoskeletons, flywheel, pneumatic, and closed-loop microprocessor controlled motor driven systems. Each technology has unique advantages and disadvantages. The Advanced Exercise Concepts project oversees development of candidate next generation exercise countermeasures hardware, performs trade studies of current and state of the art exercise technologies, manages and supports candidate systems physiological evaluations with human test subjects on the ground, in flight analogs and flight. The near term goal is evaluation of candidate systems in flight, culminating in an integrated candidate next generation exercise countermeasures suite on the ISS which coalesces research findings from HRP disciplines in the areas of exercise performance for muscle, bone, cardiovascular, sensorimotor, behavioral health, and nutrition for optimal benefit to the crew.
Countermeasures↗
Apparatus for improving the fuel efficiency of a gas turbine engine
An energy recovery system is provided for an aircraft gas turbine engine of the type in which some of the pneumatic energy developed by the engine is made available to support systems such as an environmental control system. In one such energy recovery system, some of the pneumatic energy made available to but not utilized by the support system is utilized to heat the engine fuel immediately prior to the consumption of the fuel by the engine. Some of the recovered energy may also be utilized to heat the fuel in the fuel tanks. Provision is made for multiengine applications wherein energy recovered from one engine may be utilized by another one of the engines or systems associated therewith.
Coffinberry, G. A.↗
Method for improving the fuel efficiency of a gas turbine engine
An energy recovery system is provided for an aircraft gas turbine engine of the type in which some of the pneumatic energy developed by the engine is made available to support systems such as an environmental control system. In one such energy recovery system, some of the pneumatic energy made available to but not utilized by the support system is utilized to heat the engine fuel immediately prior to the consumption of the fuel by the engine. Some of the recovered energy may also be utilized to heat the fuel in the fuel tanks. Provision is made for multiengine applications wherein energy recovered from one engine may be utilized by another one of the engines or systems associated therewith.
Coffinberry, G. A.↗