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Full-Text Articles in Engineering
Experimental Investigation Of Leak-Rate Performance Of A Subscale Composite Elastomer-Retainer Docking Seal, Nicholas Garafolo, Christopher Daniels
Experimental Investigation Of Leak-Rate Performance Of A Subscale Composite Elastomer-Retainer Docking Seal, Nicholas Garafolo, Christopher Daniels
Dr. Christopher C Daniels
A novel docking seal was investigated for application to the main interface seal of NASA’s low-impact docking system. This interface seal was designed to maintain acceptable leak rates while being exposed to the harsh environmental conditions of outer space. In this experimental evaluation, the leak rate of a candidate docking-seal assembly was characterized and evaluated. The composite seal was manufactured from silicone elastomer S0383-70, vacuum molded into a metal retaining ring. Four seal designs were considered with unique characteristic heights. The leak-rate performance was characterized through a mass point leak-rate method by monitoring gas properties within an internal control volume. …
Evaluation Of A Novel Seal For Space Applications, Christopher Daniels, Nicholas Garafolo, Marta Panickar, Ian Smith
Evaluation Of A Novel Seal For Space Applications, Christopher Daniels, Nicholas Garafolo, Marta Panickar, Ian Smith
Dr. Christopher C Daniels
To meet the requirements of future exploration missions to low Earth orbit, to the moon, and to Mars, a new docking system was developed by the national Aeronautics and Space Administration.
Optimized Shapes Of Oscillating Resonators For Generating High-Amplitude Pressure Waves, Xiaofan Li, Joshua Finkbeiner, Ganesh Raman, Christopher Daniels, Bruce Steinetz
Optimized Shapes Of Oscillating Resonators For Generating High-Amplitude Pressure Waves, Xiaofan Li, Joshua Finkbeiner, Ganesh Raman, Christopher Daniels, Bruce Steinetz
Dr. Christopher C Daniels
No abstract provided.
The Friction Behavior Of Individual Components Of A Spark-Ignition Engine During Warm-Up, Christopher Daniels, Minel Braun
The Friction Behavior Of Individual Components Of A Spark-Ignition Engine During Warm-Up, Christopher Daniels, Minel Braun
Dr. Christopher C Daniels
The research presented herein fills a void in the published literature through investigation of transient friction contributions by individual internal combustion engine components during simulated engine warm-up. Currently, engine manufacturers design internal combustion engines primarily for use at steady-state operating conditions with little design consideration for transient engine warm-up. Using the motoring torque waveform and cycle-averaged data of a spark-ignition internal combustion engine, the present work determined the friction behavior of individual engine component assemblies, including the valve train, pistons and connecting rods, oil pump, and crankshaft of a modern internal combustion engine. A common criticism of the standard motoring …
Effect Of System Variables On The Uncertainty Of The Mass Point Leak Rate Methodology Using First-Order Regression, Christopher Daniels, Nicholas Garafolo
Effect Of System Variables On The Uncertainty Of The Mass Point Leak Rate Methodology Using First-Order Regression, Christopher Daniels, Nicholas Garafolo
Dr. Christopher C Daniels
Advances in nondestructive testing for leak rate characterisation are rare because procedures are well accepted; however, for many critical applications, an understanding of the accuracy and reliability of a reported leak rate is equally as important as the leak rate itself (e.g., manned spacecraft and nuclear power industry). Although it is known that the mass point leak rate method can achieve high accuracies, the measurement uncertainty and limitations of the method are less understood. Using a least-squares regression on a mass–time population and a statistical analysis of regression uncertainty, this study investigated the influence of (1) differential pressure, (2) steady-state …
A Compressible Permeation Approach To Elastomeric Space Seal Characterization, Nicholas Garafolo, Christopher Daniels
A Compressible Permeation Approach To Elastomeric Space Seal Characterization, Nicholas Garafolo, Christopher Daniels
Dr. Christopher C Daniels
The development of elastomeric face seals is imperative for NASA’s manned space flight program. Lacking in the development of state-of-the-art space seals was a technique for predicting the performance of candidate designs prior to experimental characterization. To this end, a physics-based model for compressible permeation in elastomeric face seals was developed to provide a predictive methodology for designers and researchers. In this novel approach for seal research, compressibility effects and the dependence of permeability on pressure was retained. Two independent permeation parameters arose from an exact, analytical solution to the one-dimensional permeation transport equations. The application of the derived transport …
Experimental Flow Patterns And Pressure Characteristics In A Single Hydrostatic Pocket Of Variable Depth, Minel Braun, Christopher Daniels, D. Peloso, Robert. Hendricks
Experimental Flow Patterns And Pressure Characteristics In A Single Hydrostatic Pocket Of Variable Depth, Minel Braun, Christopher Daniels, D. Peloso, Robert. Hendricks
Dr. Christopher C Daniels
This article presents the results of an investigation into the flow patterns and pressure profiles that develop in a single pocket of a simulated hydrostatic bearing.The investigation has a dual purpose. The first is to determine the physics of the fluid patterns that develop under certain operating and geometry conditions; the second is to provide experimental information to the numerical practitioner for validation of numerical predictive and design codes.The flow was visualized in a hydrostatic pocket of variable depth.Two cases were considered: the first was that of a deep pocket (aspect ratio = depth/length = 1.0); the second was a …
Mass Point Leak Rate Technique With Uncertainty Analysis, Nicholas Garafolo, Christopher Daniels
Mass Point Leak Rate Technique With Uncertainty Analysis, Nicholas Garafolo, Christopher Daniels
Dr. Christopher C Daniels
The mass point leak rate technique is often the methodology of choice for quantifying leak rates as it uses simple elementary measurements, applies to gas systems of low mass, proves effective for low leak rates, and does not rely on test-gas conversions. In this methodology, a number of instantaneous mass measurements are calculated through samples of volume, pressure, gas composition, and temperature measurements over time. A regression analysis of the corresponding mass-time sample set yields the leak rate of the system. A detailed uncertainty analysis is paramount for a complete, experimental characterization of the leak rate and previously was not …
An Experimental Investigation Of Natural Convection In An Open-Ended Horizontal Annulus Using A Nonintrusive Full Flow Field Visualization Method, Minel Braun, Christopher Daniels, M. Dyko
An Experimental Investigation Of Natural Convection In An Open-Ended Horizontal Annulus Using A Nonintrusive Full Flow Field Visualization Method, Minel Braun, Christopher Daniels, M. Dyko
Dr. Christopher C Daniels
The study presented in this article aims at mapping experimentally the flow patterns in the annulus between an internally heated inner cylinder and a surrounding outer cylinder with an aspect ratio of length/diameter ~1. Both cylinders are stationary. The annulus is open axially to the ambient at both ends, and natural convection ensues when the inner cylinder is heated. The experiments are performed at temperatures of 32.2 °C (90 °F) and 65.6 °C (150 °F), corresponding to Rayleigh numbers (RaL = gβL3(Ti - T∞ /να) of 6.62 × 103 and 1.58 × 104 , respectively. This range encompasses the region …
Review Of Seal Designs On The Apollo Spacecraft, Joshua Finkbeiner, Patrick Dunlap, Bruce Steinetz, Christopher Daniels
Review Of Seal Designs On The Apollo Spacecraft, Joshua Finkbeiner, Patrick Dunlap, Bruce Steinetz, Christopher Daniels
Dr. Christopher C Daniels
The Apollo spacecraft required a variety of seal designs to support human spaceflight to the moon and to return the crew safely to Earth. High-temperature seals were required for gaps in the thermal protection system to protect the underlying structures from the high heating environment of super orbital reentry. Reliable pressure seals were also required to prevent the loss of habitable atmosphere during missions to the moon...
The Influence Of Al2o3 Particulate Reinforcement On Cyclic Stress Response And Fracture Behavior Of 6061 Aluminum Alloy, Tirumalai Srivatsan, S. Sriram, Christopher Daniels
The Influence Of Al2o3 Particulate Reinforcement On Cyclic Stress Response And Fracture Behavior Of 6061 Aluminum Alloy, Tirumalai Srivatsan, S. Sriram, Christopher Daniels
Dr. Christopher C Daniels
The cyclic stress response characteristics and cyclic fracture behavior of aluminum alloy 6061 discontinuously reinforced with particulates of Al2O3 are presented and discussed. The 6061/Al2O3 composite specimens and the unreinforced 6061 aluminum alloy were cyclically deformed using tension-compression loading under constant total strain amplitude control. Both the composite and the unreinforced alloy exhibited softening to failure from the onset of cyclic deformation. The degree of softening was observed to increase at the elevated test temperature for both the composite and the unreinforced counterpart. The intrisic micromechanisms controlling the stress response characteristics during fully-reversed cyclic …