SEARCH · Engineering Papers
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Attitude control system designed for rockets regulates duty cycle of pneumatic valves so less fuel is required. Operation time of each valve is directly proportional to error signal and the dead band about a null is controlled by independently adjustable threshold circuits.
Valve throttles transfer of vapor between heat input surface and heat rejection surface of heat pipe to control rate of transfer of energy. Valve is operated by control signals which sense temperatures or pressures.
Incorporation of isolation valves in high pressure oxygen supply system prevents occurrence of shock ignition when valves are opened. Specifications of equipment show flow rates, pressure ratings, and service life. Illustration of equipment is provided.
Design and development of two types of pumps for handling liquefied gases are discussed. One pump uses mechanical valve shift and other uses pneumatic valve shift. Illustrations of pumps are provided and detailed description of operation is included.
Configuration of poppet valve with zero clearance sudden initial contact is described. Detailed description of valve operation is presented and diagram of components is illustrated.
An ultrasonic contact sensor engineering prototype leak detection system was developed and its capabilities under cryogenic operations demonstrated. The results from tests indicate that the transducer performed well on liquid hydrogen plumbing, that flow and valve actuation could be monitored, and that the phase change from gaseous to liquid hydrogen could be detected by the externally mounted transducers. Tests also demonstrate the ability of the system to detect internal leaks past valve seats and to function as a flow meter. Such a system demonstrates that it is not necessary to break into welded systems to locate internal leaks.
A program designed to characterize an experimental fluoroelastomer material designated AF-E-124D, is examined. Tests conducted include liquid nitrogen load compression tests, flexure tests and valve seal tests, ambient and elevated temperature compression set tests, and cleaning and flushing fluid exposure tests. The results of these tests indicate the AF-E-124D is a good choice for a cryogenic seal, since it exhibits good low temperature sealing characteristics and resistance to permanent set. The status of this material as an experimental fluorelastomer is stressed and recommended. Activity includes definition and control of critical processing to ensure consistent material properties. Design, fabrication and test of this and other materials is recommended in valve and static seal applications.
An automatic control apparatus for a liquid cooling garment is described that is responsive to actual physiological needs during work and rest periods of a man clothed in the liquid cooling garment. Four skin temperature readings and a reading taken at the external portion of the auditory meatus are added and used in the control signal for a temperature control valve regulating inlet water temperature for the liquid cooling garment. The control apparatus comprises electronic circuits to which the temperatures are applied as control signals and an electro-pneumatic transducer attached to the control valve.
An electronic circuit for processing arterial blood pressure waveform signals is described. The circuit detects blood pressure as the heart pumps blood through the aortic valve and the pressure distribution caused by aortic valve closure. From these measurements, timing signals for use in measuring the left ventricular ejection time is determined, and signals are provided for computer monitoring of the cardiovascular system. Illustrations are given of the circuit and pressure waveforms.
A pressure ramp programmer model was designed, fabricated and tested. This model, in conjunction with an automatic blood pressure monitor, automatically controls the pressure in the blood pressure monitor arterial cuff. The cuff pressurization cycle is designed to maximize accuracy and repeatability of blood pressure measurements. The key feature of this automatic cycle is rapid blood pressure cuff bleed down from an initial setting until systolic (diastolic) pressure is encountered followed by a short repressurization and slow bleed, long enough to permit accurate systolic (diastolic) pressure determination. The system includes a pressure reservoir which bleeds the cuff through a precision needle valve; a solenoid valve which permits rapid pressurization from the reservoir; and a pressure sensor which provides information for bleed rate and set point controls. Korotkoff sound signals from a microphone in the blood pressure cuff (not part of the system) provide decision information to the digital control system. The system completed a series of engineering tests using simulated Korotkoff sound inputs. The system performed successfully in all cases and was stable over an extended period of time.
The Apollo 11 service module and the command module (CM) reaction control system performed satisfactorily throughout the mission. Two anomalies which occurred were an inadvertent isolation valve closure during command and service module/Saturn S4B/lunar module separation and a failure of a CM thruster to respond to automatic commands. The isolation valves were later opened by the crew and remained open during the remainder of the mission. The cause of the closure was determined to be the shock loads generated during separation. The CM engine malfunction was caused by a faulty terminal board connector. All system parameters were normal during the mission, and all mission requirements were satisfied.
The flightweight components were adapted to form the basic engine assembly. The water cooled test adapters for use in wind tunnel tests were fabricated. Commercially available valves were selected for the coolant control system. The simplification of the temperature control concept and of the absence of weight and volume constraints made it possible to use these valves. Various calibration tests are also discussed.
The behavior characteristics of direct-acting gas pressure regulators are discussed in terms of spring force, flow force, and friction force. The dynamics of the metering valve and bellows assembly are described by equating all forces on the valve to zero. Continuity equations for the regulator are derived. Simulations are carried out to determine effects of sensing orifice diameter, poppet stem friction, output volume, and supply pressure on regulator behavior. Several regulator configurations are studied.
A system is described for monitoring the respiratory process in which the gas flow rate and the frequency of respiration and expiration cycles can be determined on a real time basis. A face mask is provided with one-way inlet and outlet valves where the gas flow is through independent flowmeters and through a mass spectrometer. The opening and closing of a valve operates an electrical switch, and the combination of the two switches produces a low frequency electrical signal of the respiratory inhalation and exhalation cycles. During the time a switch is operated, the corresponsing flowmeter produces electric pulses representative of the flow rate; the electrical pulses being at a higher frequency than that of the breathing cycle and combined with the low frequency signal. The high frequency pulses are supplied to conventional analyzer computer which also receives temperature and pressure inputs and computes mass flow rate and totalized mass flow of gas. From the mass spectrometer, components of the gas are separately computed as to flow rate. The electrical switches cause operation of up-down inputs of a reversible counter. The respective up and down cycles can be individually monitored and combined for various respiratory measurements.
The advanced technology applicable to oxygen/hydrogen systems for auxiliary propulsion systems and other high energy upper stage applications is being developed. Turbopump, propellant conditioner (gas generator and heat exchanger), thruster, igniter, valve, and flow controller components are being evaluated. A brief description of turbopump, conditioner, valve, and thruster experimental programs is presented. Design and hot-firing test data are discussed.
The requirements of the Space Shuttle bipropellant reaction control system engine technology contract and the scheduled contract effort are presented herein. The requirements included an engine concept scalable from 400 to 1100 lbf, with a 100 mission life employing N2O4/MMH propellants. Emphasis is placed on reusability and minimum post-flight servicing. The engine components are reviewed and their selection is supported by tradeoff analyses, thrust chamber firing test data, materials test data, and metallurgical evaluations. The materials test data indicate that the proposed silicide coated columbium chamber and uncoated columbium injector have the potential of meeting the mission life requirements. The engine valve trade studies resulted in the selection of a torque motor operated bipropellant valve configuration. Fuel vortex film cooling of the insulated chamber is described together with the fuel vortex film cooling scaling parameter and its verification by test data to a thrust level of 5500 lbf.
The potential gain in the reliability of reusable long-term mission vehicles through the minimization of component damage due to the ingestion of particulate contamination by feed system components has been recognized by the NASA-LeRC and MDAC, and a program to investigate these problems has been completed. This investigation covered the determination of the cycle life of a typical 2-in. poppet type of shutoff valve in an uncontaminated GH2 environment and then compared this component performance with simulated operation with GN2 and LN2 containing controlled amounts of AL2O2 contaminant particles. The original valve design was tested for contamination damage tolerance characteristics under full flow and cyclic operating conditions, redesigned to improve the damage tolerance to contaminants and then retested. A second method of approach to damage tolerance control was investigated through the evaluation of various types of particulate separation devices. The study included various types of dynamic separators but did not cover conventional filter assemblies.
A dispenser particularly suited for use in dispensing potable water into food and beverage reconstitution bags is described. The dispenser is characterized by an expansible chamber, selectively adjustable stop means for varying the maximum dimensions, a rotary valve, and a linear valve coupled in a cooperating relation for delivering potable water to and from the chamber.