Fluid and Machinery Dynamics

The Institute is recognized for its contributions to fluid machinery and piping technology, structural and fluid dynamics, and fluid systems engineering. Staff members conduct laboratory and analytical research projects and provide testing, prototype development, and field consultation services for industry and government.

A multiyear gas flow metering research program sponsored by the Gas Research Institute (GRI) is aimed at improving gas flow measurement accuracy for natural gas production, transmission, and distribution facilities. The centerpiece of this program is the GRI Metering Research Facility (MRF) located at and operated by SwRI. During the past year, MRF facility enhancements were completed with the addition of piping headers in the test flow loops to provide better access for commercial clients worldwide to use the MRF for routine flow meter calibrations, meter research and development, and certain non-metering applications.

GRI-funded research at the MRF is aimed at investigating piping installation effects on orifice and turbine meter accuracy and assessing the performance of ultrasonic flow meters, rotary flow meters, and residential gas meters designed for low-flow rate, low-pressure applications. A new project, co-sponsored by GRI and the American Petroleum Institute, is establishing better ways of sampling pipeline gas to determine its composition, which can significantly affect flow measurement accuracy. To help transfer research results from the laboratory to the field, SwRI is developing a short course for gas company personnel, with the first course scheduled for late 1995.

The Gas Research Institute's Metering Research Facility (MRF) is located at and operated by the Institute, providing state-of-the-art research and testing capabilities to measure the performance of new and existing gas meters over a range of typical and extreme conditions. New designs of compact domestic gas meters are currently being evaluated in the distribution metering section of the MRF.

As part of SwRI's international fluid flow measurement activities, a project has been initiated with CIATEQ (Centro de Investigacion y Asistencia Technica del Estado de Querétaro, AC), to help in the design, construction, and start-up of a liquid flow meter calibration facility for CENAM (Centro Nacional De Metrologia), to be located in Querétaro, Mexico. The facility is being designed to achieve a total uncertainty of only 0.1 percent when calibrating liquid flow meters.

Gas purging, a process of displacing one gas by another, occurs on a routine basis in the natural gas industry when pipelines are brought into and taken out of service. In a project sponsored by GRI and in cooperation with the Pipeline Research Committee of the American Gas Association (A.G.A.), the purging practices outlined in the A.G.A. Purging Principles and Practices Manual are being reviewed. The objective is to develop an understanding of the scientific principles on which safe, practical purging practices can be based. The results of this program, when verified through field studies, will be integrated into computer software suitable for planning such operations.

A safety-related program for the natural gas industry involves an assessment of automatic and remote rupture detection and control techniques that can be used with existing mainline valves to achieve rapid isolation of a ruptured high-pressure gas line. While such breaks are rare, computer simulation studies conducted by SwRI under GRI sponsorship confirm industry's field experience that existing technology and equipment are sometimes unreliable in detecting and isolating mainline rupture. From this study, application guidelines have been developed to aid industry in the selection, location, and adjustment of existing protective equipment, and design techniques have been developed to improve detection reliability while minimizing false closures.

Acoustically induced vibration, noise, and fatigue failures are becoming more common in pressurized industrial flow systems such as flare lines, control valves, safety relief valves, recycle and bypass lines, and strainers. Small lines and fittings usually fail first, with cracks propagating into the main piping. SwRI has developed an extensive database of such incidents by correlating hundreds of noise, pressure, pulsation, vibration, and dynamic strain measurements made in the field. Vibration and acoustic analyses are conducted for industrial clients to assess the risk of such failures.

A finite element model of a reciprocating compressor is sued to evaluate loads and deflections that can lead to damaged bearings and failed crankshafts.

The natural gas and process industries experience a high incidence of foundation-related problems in their large reciprocating compressors. A multiyear research effort under way for the Pipeline and Compressor Research Council will develop better techniques to design new foundations and to repair existing foundations damaged by the high dynamic loads imposed by compressors. Nonlinear finite element models of the compressor frame and foundation are used to investigate the effects of design parameters on foundation cracking. Results thus far have validated some long-standing industry practices while revealing critical flaws in others.

A combustion turbine vibration monitoring and balancing diagnostic system was installed this year for the Electric Power Research Institute and a Tennessee electric utility. The CT•WATCH/ SENTINEL/SAGE hardware and software system was installed on all four units at an electric generating plant and interfaced with the unit control system. The software provides the operator with analysis, trend tracking, graphic display, and diagnostic capabilities.

Institute engineers have designed scale models of satellite fuel tanks to be placed onboard a 1996 space shuttle flight. This experiment will allow engineers to study the destabilizing fluid forces present in a fuel tank as a satellite spins about its flight path.

For a program sponsored by NASA's Lewis Research Center, the Institute is investigating how liquid motions in the propellant tanks of spinning spacecraft affect spacecraft stability and control. The experiment, part of the NASA In-Space Technology Experiment Program (IN-STEP), will be housed in the mid-deck lockers of the space shuttle on a 1996 flight. The construction phase of the experimental hardware is nearing completion. In a related SwRI internal research program, analytical models of the liquid motions in spinning tanks were developed to predict and better understand the experimental results.

Efforts continued on a NASA IN-STEP experiment to gauge the volume of liquid contained in a spacecraft tank in a low- gravity environment. Conventional gauges cannot determine liquid levels in low gravity, because the liquid does not settle in any particular part of the tank. A gauge developed by the Institute uses an oscillating piston and bellows to change the volume of the tank. The resulting gas pressure change is measured and the results used to compute the volume of gas in the tank. The volume of liquid in the tank can then be determined.

The Institute continues to examine ways that vibratory loading caused by seismic events can affect equipment used in the nuclear power and telecommunications industries. The Institute's seismic simulator, which can produce realistic earthquake motions in two axes simultaneously, is used in these studies.

Key noise sources from a reciprocating compressor are identified using acoustic intensity measurement techniques. Such studies allow engineers to develop control measures and redesign or augment existing equipment to reduce industrial noise.

Reducing noise from industrial machinery and transportation vehicles to acceptable levels is an ongoing Institute program. Vibroacoustic analysis techniques, coupled with laboratory and field measurements, have contributed to improved noise control measures for a wide class of industrial and vehicular systems. The Institute is evaluating various means of active noise control and is developing advanced engine vibration isolation technology for structure-borne noise control. Specific applications include reducing cabin noise in general aviation and rotorcraft airframes as well as noise radiated from industrial gas turbines in power plants.

1995 Annual Report SwRI Home