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Shapiro, Wilbur

Publications and source records attributed to Shapiro, Wilbur.

14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

An Advanced Helium Buffer Seal for the SSME, ATD Oxygen Pump

The present configuration of Helium Buffer Seal on the ATD oxygen pump consists of a pair of opposed carbon rings are forced axially against their containment housings. Leakage occurs through the clearance between the rings and the shaft. The total helium leakage through both sides is approximately 239 SCFM. A reduction in leakage to 50 SCFM will result in less helium storage and consequently permit a substantial increase in payload. Under Phase 1 NASA SBIR, a solid T-Ring seal was analyzed and designed that could satisfy the criteria of reducing leakage to 50 SCFM or less. The design makes maximum use of available length and employs a mid length row of hydrostatic orifaces that feed buffer helium directly into a 2 to 3 mil clearance region. The flow splits into opposite paths to buffer oxygen gas on one side and hydrogen gas on the turbine side. The seal employs opposed hydrostatic tapered land secondary seals that provide friction free support of the primary seal and allows the primary seal to follow rotor excursion and maintain concentric operating clearance . The predicted performance of the T-seal is excellent with operation at a safe film thickness of 2 to 2.5 mils and leakage less than 50 SCFM.

Shapiro, Wilbur↗
NASA NTRS2005

Users' Manual for Computer Code SPIRALI Incompressible, Turbulent Spiral Grooved Cylindrical and Face Seals

The SPIRALI code predicts the performance characteristics of incompressible cylindrical and face seals with or without the inclusion of spiral grooves. Performance characteristics include load capacity (for face seals), leakage flow, power requirements and dynamic characteristics in the form of stiffness, damping and apparent mass coefficients in 4 degrees of freedom for cylindrical seals and 3 degrees of freedom for face seals. These performance characteristics are computed as functions of seal and groove geometry, load or film thickness, running and disturbance speeds, fluid viscosity, and boundary pressures. A derivation of the equations governing the performance of turbulent, incompressible, spiral groove cylindrical and face seals along with a description of their solution is given. The computer codes are described, including an input description, sample cases, and comparisons with results of other codes.

Walowit, Jed A.↗
NASA NTRS2004

Numerical, Analytical, Experimental Study of Fluid Dynamic Forces in Seals: Description of Gas Seal Codes GCYLT and GFACE - Volume 2

The objectives of the program were to develop computational fluid dynamics (CFD) codes and simpler industrial codes for analyzing and designing advanced seals for air-breathing and space propulsion engines. The CFD code SCISEAL is capable of producing full three-dimensional flow field information for a variety of cylindrical configurations. An implicit multidomain capability allow the division of complex flow domains to allow optimum use of computational cells. SCISEAL also has the unique capability to produce cross-coupled stiffness and damping coefficients for rotordynamic computations. The industrial codes consist of a series of separate stand-alone modules designed for expeditious parametric analyses and optimization of a wide variety of cylindrical and face seals. Coupled through a Knowledge-Based System (KBS) that provides a user-friendly Graphical User Interface (GUI), the industrial codes are PC based using an OS/2 operating system. These codes were designed to treat film seals where a clearance exists between the rotating and stationary components. Leakage is inhibited by surface roughness, small but stiff clearance films, and viscous pumping devices. The codes have demonstrated to be a valuable resource for seal development of future air-breathing and space propulsion engines.

Liang, Anita D.↗
NASA NTRS2004

Numerical, Analytical, Experimental Study of Fluid Dynamic Forces in Seals: Executive Summary and Description of Knowledge-Based System - Volume 1

The objectives of the program were to develop computational fluid dynamics (CFD) codes and simpler industrial codes for analyzing and designing advanced seals for air-breathing and space propulsion engines. The CFD code SCISEAL is capable of producing full three-dimensional flow field information for a variety of cylindrical configurations. An implicit multidomain capability allows the division of complex flow domains to allow optimum use of computational cells. SCISEAL also has the unique capability to produce cross-coupled stiffness and damping coefficients for rotordynamic computations. The industrial codes consist of a series of separate stand-alone modules designed for expeditious parametric analyses and optimization of a wide variety of cylindrical and face seals. Coupled through a Knowledge-Based System (KBS) that provides a user-friendly Graphical User Interface (GUI), the industrial codes are PC based using an OS/2 operating system. These codes were designed to treat film seals where a clearance exists between the rotating and stationary components. Leakage is inhibited by surface roughness, small but stiff clearance films, and viscous pumping devices. The codes have demonstrated to be a valuable resource for seal development of future air-breathing and space propulsion engines.

Liang, Anita D.↗
NASA NTRS2004

Numerical, Analytical, Experimental Study of Fluid Dynamic Forces in Seals: Description of Spiral-Groove Codes SPIRALG and SPIRALI - Volume 3

The objectives of the program were to develop computational fluid dynamics (CFD) codes and simpler industrial codes for analyzing and designing advanced seals for air-breathing and space propulsion engines. The CFD code SCISEAL is capable of producing full three-dimensional flow field information for a variety of cylindrical configurations. An implicit multidomain capability allow the division of complex flow domains to allow optimum use of computational cells. SCISEAL also has the unique capability to produce cross-coupled stiffness and damping coefficients for rotordynamic computations. The industrial codes consist of a series of separate stand-alone modules designed for expeditious parametric analyses and optimization of a wide variety of cylindrical and face seals. Coupled through a Knowledge-Based System (KBS) that provides a user-friendly Graphical User Interface (GUI), the industrial codes are PC based using an OS/2 operating system. These codes were designed to treat film seals where a clearance exists between the rotating and stationary components. Leakage is inhibited by surface roughness, small but stiff clearance films, and viscous pumping devices. The codes have demonstrated to be a valuable resource for seal development of future air-breathing and space propulsion engines.

Liang, Anita D.↗
NASA NTRS2004

Numerical, Analytical, Experimental Study of Fluid Dynamic Forces in Seals: Description of Seal Dynamics Code DYSEAL and Labyrinth Seals Code KTK - Volume 5

The objectives of the program were to develop computational fluid dynamics (CFD) codes and simpler industrial codes for analyzing and designing advanced seals for air-breathing and space propulsion engines. The CFD code SCISEAL is capable of producing full three-dimensional flow field information for a variety of cylindrical configurations. An implicit multidomain capability allow the division of complex flow domains to allow optimum use of computational cells. SCISEAL also has the unique capability to produce cross-coupled stiffness and damping coefficients for rotordynamic computations. The industrial codes consist of a series of separate stand-alone modules designed for expeditious parametric analyses and optimization of a wide variety of cylindrical and face seals. Coupled through a Knowledge-Based System (KBS) that provides a user-friendly Graphical User Interface (GUI), the industrial codes are PC based using an OS/2 operating system. These codes were designed to treat film seals where a clearance exists between the rotating and stationary components. Leakage is inhibited by surface roughness, small but stiff clearance films, and viscous pumping devices. The codes have demonstrated to be a valuable resource for seal development of future air-breathing and space propulsion engines

Shapiro, Wilbur↗
NASA NTRS1996

Industrial Computer Codes

This is an overview of new and updated industrial codes for seal design and testing. GCYLT (gas cylindrical seals -- turbulent), SPIRALI (spiral-groove seals -- incompressible), KTK (knife to knife) Labyrinth Seal Code, and DYSEAL (dynamic seal analysis) are covered. CGYLT uses G-factors for Poiseuille and Couette turbulence coefficients. SPIRALI is updated to include turbulence and inertia, but maintains the narrow groove theory. KTK labyrinth seal code handles straight or stepped seals. And DYSEAL provides dynamics for the seal geometry.

Shapiro, Wilbur↗
NASA NTRS1995

Space Mechanisms Lessons Learned Study. Volume 1: Summary

Hundreds of satellites have been launched to date. Some have operated extremely well and others have not. In order to learn from past operating experiences, a study was conducted to determine the conditions under which space mechanisms (mechanically moving components) have previously worked or failed. The study consisted of: (1) an extensive literature review that included both government contractor reports and technical journals; (2) communication and visits (when necessary) to the various NASA and DOD centers and their designated contractors (this included contact with project managers of current and prior NASA satellite programs as well as their industry counterparts); (3) requests for unpublished information to NASA and industry; and (4) a mail survey designed to acquire specific mechanism experience. The information obtained has been organized into two volumes. Volume 1 provides a summary of the lessons learned, the results of a needs analysis, responses to the mail survey, a listing of experts, a description of some available facilities and a compilation of references. Volume 2 contains a compilation of the literature review synopsis.

Shapiro, Wilbur↗
NASA NTRS1995

Space Mechanisms Lessons Learned Study. Volume 2: Literature Review

Hundreds of satellites have been launched to date. Some have operated extremely well and others have not. In order to learn from past operating experiences, a study was conducted to determine the conditions under which space mechanisms (mechanically moving components) have previously worked or failed. The study consisted of an extensive literature review that included both government contractor reports and technical journals, communication and visits (when necessary) to the various NASA and DOD centers and their designated contractors (this included contact with project managers of current and prior NASA satellite programs as well as their industry counterparts), requests for unpublished information to NASA and industry, and a mail survey designed to acquire specific mechanism experience. The information obtained has been organized into two volumes. Volume 1 provides a summary of the lesson learned, the results of a needs analysis, responses to the mail survey, a listing of experts, a description of some available facilities, and a compilation of references. Volume 2 contains a compilation of the literature review synopsis.

Shapiro, Wilbur↗
NASA NTRS1994

Code GFACE: Gas lubricated face seals in laminar regime

A viewgraph presentation is given of the capabilities of the computer code GFACE. Capabilities include: varying geometries, including Rayleigh step, tapered land, and hydrostatic; variable grid; z, x-x, and y-y degrees of freedom; can determine position as a function of load; and English or SI units.

Shapiro, Wilbur↗
NASA NTRS1991

Industrial Code Development

The industrial codes will consist of modules of 2-D and simplified 2-D or 1-D codes, intended for expeditious parametric studies, analysis, and design of a wide variety of seals. Integration into a unified system is accomplished by the industrial Knowledge Based System (KBS), which will also provide user friendly interaction, contact sensitive and hypertext help, design guidance, and an expandable database. The types of analysis to be included with the industrial codes are interfacial performance (leakage, load, stiffness, friction losses, etc.), thermoelastic distortions, and dynamic response to rotor excursions. The first three codes to be completed and which are presently being incorporated into the KBS are the incompressible cylindrical code, ICYL, and the compressible cylindrical code, GCYL.

Shapiro, Wilbur↗
NASA NTRS1990

Analysis and design of helium-buffered face seals for the SSME high-pressure oxygen turbopump

One form of a gas-buffered seal consists of two opposed fluid-film face seals, each mating against a single collar. The buffer fluid is introduced at the OD and flows through the radial clearances of each seal to opposite and separate environments at the IDs. This arrangement was investigated for the helium buffer seals applied to the oxidizer pump of the Space Shuttle Main Engine (SSME). A variety of face configurations were considered, and the self-energized-hydrostatic and spiral-groove geometries were selected for detailed evaluation. Fluid-film performance, dynamic response, and thermoelastic distortions were determined. Because of very high temperature gradients, distortions of the turbine-side seal ring were excessive. Otherwise, performance was excellent in all respects.

Shapiro, Wilbur↗
NASA NTRS1989

Advanced helium purge seals for Liquid Oxygen (LOX) turbopumps

Program objectives were to determine three advanced configurations of helium buffer seals capable of providing improved performance in a space shuttle main engine (SSME), high-pressure liquid oxygen (LOX) turbopump environment, and to provide NASA with the analytical tools to determine performance of a variety of seal configurations. The three seal designs included solid-ring fluid-film seals often referred to as floating ring seals, back-to-back fluid-film face seals, and a circumferential sectored seal that incorporated inherent clearance adjustment capabilities. Of the three seals designed, the sectored seal is favored because the self-adjusting clearance features accommodate the variations in clearance that will occur because of thermal and centrifugal distortions without compromising performance. Moreover, leakage can be contained well below the maximum target values; minimizing leakage is important on the SSME since helium is provided by an external tank. A reduction in tank size translates to an increase in payload that can be carried on board the shuttle. The computer codes supplied under this program included a code for analyzing a variety of gas-lubricated, floating ring, and sector seals; a code for analyzing gas-lubricated face seals; a code for optimizing and analyzing gas-lubricated spiral-groove face seals; and a code for determining fluid-film face seal response to runner excitations in as many as five degrees of freedom. These codes proved invaluable for optimizing designs and estimating final performance of the seals described.

Shapiro, Wilbur↗
NASA NTRS1985

Seal Technology for Liquid Oxygen (LOX) Turbopumps

Two types of advanced seals for liquid oxygen (LOX) turbopumps were investigated. One was a spiral-groove face seal whose function is to seal high-pressure LOX at the impeller end of the turbopump. The other was a floating-ring, Rayleigh-step, helium buffered seal used to prevent LOX ingress to the turbine side of the unit. For each seal type, two sizes were investigated (50 and 20 mm). A turbine-driven test rig was designed and manufactured, and a test program was completed on the 50 mm floating-ring, Rayleigh-step, helium buffered seal. Significant results were: vaporization in the flow path could cause failure by overheating; therefore, the spiral-groove pumping portion of the seal that provides the fluid film must circulate fluid without disruption if vaporization occurs in the sealing dam. This is successfully accomplished by a pressure-balanced spiral-groove concept that is described. The spiral-groove configuration is affected by turbulence in the fluid film and pressure drops due to fluid inertia at sudden contractions. The net results of these effects are deep grooves, large operating films, and high power loss when compared against seals operating with laminar films. Turbulence and inertia are induced by the high-density and low-viscosity characteristics of LOX. The program clearly pointed out the need to consider system environmental factors such as thermal and centrifugal distortions and rotor vibrations in the seal design.

Shapiro, Wilbur↗