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Results for “Hydraulic system”

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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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Space shuttle recommendations based on aircraft maintenance experience

Space shuttle design recommendations based on aircraft maintenance experience are developed. The recommendations are specifically applied to the landing gear system, nondestructive inspection techniques, hydraulic system design, materials and processes, and program support.

Spears, J. M.↗
NASA NTRS1976

The F-12 series aircraft approach to design for control system reliability

The F-12 series aircraft control system design philosophy is reviewed as it pertains to functional reliability. The basic control system, i.e., cables, mixer, feel system, trim devices, and hydraulic systems are described and discussed. In addition, the implementation of the redundant stability augmentation system in the F-12 aircraft is described. Finally, the functional reliability record that has been achieved is presented.

Schenk, F. L.↗
NASA NTRS1981

Investigation of creep by use of closed loop servo-hydraulic test system

Creep tests were conducted by means of a closed loop servo-controlled materials test system. These tests are different from the conventional creep tests in that the strain history prior to creep may be carefully monitored. Tests were performed for aluminum alloy 6061-0 at 150 C and monitored by a PDP 11/04 minicomputer at a preset constant plastic-strain rate prehistory. The results show that the plastic-strain rate prior to creep plays a significant role in creep behavior. The endochronic theory of viscoplasticity was applied to describe the observed creep curves. The concepts of intrinsic time and strain rate sensitivity function are employed and modified according to the present observation.

Wu, H. C.↗
NASA NTRS1993

Study of hydraulic actuation system for Space Shuttle main engine propellant valves

Recent performance concerns involving the Space Shuttle Main Engine Propellant Valve Actuator assemblies prompted the NASA Marshall Space Flight Center to request an independent design assessment. Moog Inc. responded to this request and received a study contract with objectives of increasing valve reliability, decreasing maintenance costs while preserving the existing design interfaces. The results of the Propellant Valve Actuation System review focus on contamination control and the bypass valve design. Three proof of concept bypass valves employing design changes were built and successfully tested. Test results are presented.

Ewel, Bob↗
NASA NTRS2006

Serial Charging Test on High Capacity Li-Ion Cells for the Orbiter Advanced Hydraulic Power System

Although it looks like module level voltage drives the cutoff for charge, the actual cutoff is due to unbalanced cell voltages that drive the module voltage up. Individual cell voltage drives the cutoff for discharge Low resistance cells are the first to reach the low-voltage cutoff Cell-to-Cell voltage differences are generally small and show similar trends for each cycle Increase for a distinct window during charge and at the end of discharge Increase in max to min cell voltage difference with time/cycles Decrease in max to min cell voltage difference during high current pulses with time/cycles Individual cell voltage trends (with respect to other cells) are very repeatable from cycle to cycle, although voltage slowly degrades with time/cycles (resistance growth) Much more difference observed near end of discharge Little change in order of cell voltage (cell with highest voltage to cell with lowest voltage) Temp sensor on the side of cell (between 2 cells) shows much greater rise during discharge than for single cell tests (18 C vs 5 C) Conclusion: Serial Charging of this string of cells is feasible as it has only a minor impact on useful capacity

Jeevarajan, Judith A.↗
DOE OSTI2020

A Probabilistic Model-Based Diagnostic Framework for Nuclear Engineering Systems

A fault diagnostic framework was investigated in this study for applications in thermal–hydraulic systems of nuclear power plants. The proposed framework consists of quantitative model-based diagnosis, statistical change detection and probabilistic reasoning. The use of physics-based diagnostic models provides high detection sensitivity and allows noise and measurement uncertainty to be incorporated robustly. Performance-related parametric models for each component are constructed based on first principles. Numerical model residuals are generated using the concept of analytical redundancy. Statistical change detection methods are employed to detect non-zero residuals in the presence of uncertainty. The diagnosis task is performed using Bayesian inference to detect and localize possible faults. Application to a single-phase heat exchanger for demonstration showed that the proposed probabilistic framework can provide improved results in comparison with traditional approaches while remaining less sensitive to false alarms in the presence of measurement and modeling uncertainty.

Bayesian network↗
NASA NTRS1987

Fault Detection and Isolation for Hydraulic Control

Pressure sensors and isolation valves act to shut down defective servochannel. Redundant hydraulic system indirectly senses failure in any of its electrical control channels and mechanically isolates hydraulic channel controlled by faulty electrical channel so flat it cannot participate in operating system. With failure-detection and isolation technique, system can sustains two failed channels and still functions at full performance levels. Scheme useful on aircraft or other systems with hydraulic servovalves where failure cannot be tolerated.

Source record↗
DOE OSTI2024

The MOOSE Thermal Hydraulics Module

The Multiphysics Object-Oriented Simulation Environment (MOOSE) is an open-source object-oriented finite element framework written in C++ (Lindsay et al., 2022). The Thermal Hydraulics Module (THM) is an optional MOOSE physics module that provides capabilities for studying thermal hydraulic systems. Its core capability lies in assembling a network of coupled components, for instance, pipes, junctions, and valves. THM provides several new systems to MOOSE to enable and facilitate thermal hydraulic simulations, most notably the Components system, which provides a higher-level syntax to MOOSE’s lower-level objects. This system is extensible by the user, but the current library primarily includes components based on a one-dimensional, single-phase, variable-area, compressible flow model, as well as heat conduction.

42 ENGINEERING↗
NASA NTRS1972

Use of the flight simulator in the design of a STOL research aircraft.

Piloted simulator tests on the NASA-Ames Flight Simulator for Advanced Aircraft motion base played a major role in guiding the design of the Modified C-8A 'Buffalo' augmentor wing jet flap STOL research airplane. Design results are presented for the flight control systems, lateral-directional SAS, hydraulic systems, and engine and thrust vector controls. Emphasis is given to lateral control characteristics on STOL landing approach, engine-out control and recovery techniques in the powered-lift regime, and operational flight procedures which affected airplane design.

Spitzer, R. E.↗
NASA NTRS1977

Cost-effective actuator tester

Group of preprogrammed plug-in cards and control module converts breadboard control electronics of actuator assembly to actuator tester. System utilizes electronic control, and hydraulic systems of breadboard actuator into which it is installed.

Kopp, G. F.↗
NASA NTRS1976

Higher harmonic rotor blade pitch control

Tests of a model 'Reverse Velocity Rotor' system at high advance ratios and with twice-per-revolution cyclic pitch control were made under joint Navy-NASA sponsorship in the NASA, Ames 12 ft. pressure tunnel. The results showed significant gains in rotor performance at all advance ratios by using twice-per-revolution control. Detailed design studies have been made of alternative methods of providing higher harmonic motion including four types of mechanical systems and an electro-hydraulic system. The relative advantages and disadvantages are evaluated on the basis of stiffness, weight, volume, reliability and maintainability.

Ewans, J. R.↗
NASA NTRS2004

Intelligent Automation Approach for Improving Pilot Situational Awareness

Automation in the aviation domain has been increasing for the past two decades. Pilot reaction to automation varies from highly favorable to highly critical depending on both the pilot's background and how effectively the automation is implemented. We describe a user-centered approach for automation that considers the pilot's tasks and his needs related to accomplishing those tasks. Further, we augment rather than replace how the pilot currently fulfills his goals, relying on redundant displays that offer the pilot an opportunity to build trust in the automation. Our prototype system automates the interpretation of hydraulic system faults of the UH-60 helicopter. We describe the problem with the current system and our methodology for resolving it.

Spirkovska, Lilly↗