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Natural Gas Engine Gives Safe School Bus a Boost


Senior Research Engineer John Kubesh

Engineers at Southwest Research Institute have completed the first phase of a two-year program to develop a fully electronically controlled natural gas engine for use in school and commercial buses. The new engine design is one aspect of a research and development contract funded by the U.S. Department of Energy and managed by the National Renewable Energy Laboratory (NREL) to develop an ultra-safe school bus powered by natural gas.

Southwest Research Institute is working in alliance with Deere Power Systems Group, Waterloo, Iowa, a leader in diesel engines; Blue Bird Corporation, Fort Valley, Georgia, a leading manufacturer of school buses; and the CNG Cylinder Company, Long Beach, California.

The SwRI design employs an existing PowerTech 8.1-liter Deere natural gas engine previously modified by SwRI engineers to be a state-of-the-art electronically controlled engine. The modified engine has electronic fuel injection, an electronic drive-by-wire throttle actuator, an electronically controlled wastegate, and a direct fire, coil-on-plug ignition system.

“This engine is unique because previous natural gas engines developed at SwRI have not had an electronic control system that controls all of these functions,” says Senior Research Engineer John Kubesh (right) of the Engine and Vehicle Research Division at the Institute. “Our design uses advanced technology in both the engine hardware and the control systems.” So far, the modified engine has demonstrated low emission levels while providing good engine performance and fuel efficiency; no natural gas engine currently in production for heavy- duty vehicles offers this performance combination. “Deere plans to place a version of this engine into production this year,” he adds.

The fuel system draws from a natural gas supply contained in four composite- wrapped aluminum cylinders within the frame rails underneath the bus, between the steering and rear axles. The bus is expected to have an operating range in excess of 300 miles, which is typical for a heavy-duty vehicle. “School buses in particular are ideal candidates for natural gas use because routes are generally well defined and the fuel requirements and refueling intervals are well known,” notes Kubesh. “Natural gas is plentiful and economical, and natural gas engines can be operated at very lean conditions, which translates into low emissions and high efficiency.”

Over the next several months, SwRI engineers will seek to improve the engine by evaluating control strategies that directly affect the ability of the new electronic control system to maintain the desired air-fuel ratio, spark timing, boost pressure, and other parameters during steady state and transient operation. Institute engineers are developing other control system features to provide knock and misfire detection and catalyst efficiency monitoring.

The engine is undergoing lean misfire and knock limit tests to determine its limits of operation, as well as tests to identify the influence of various engine components on the performance and emissions output of the engine. One objective of the test series is to lower NOx emissions while maintaining the current engine efficiency level.

Once proven, the engine will be installed in the prototype bus currently under design at Blue Bird. The “ultra-safe” bus will be lighter in weight for optimum fuel efficiency, and will have such safety features as improved lighting (headlights and safety lights), a larger center aisle for better access to emergency exits, extra windshield glass for improved visibility, and a child restraint system. The bus will also be equipped with a rear view camera and special motion sensors able to detect pedestrians near the perimeter of the bus. “The engine/bus integration process and a 10,000 mile field demonstration are slated to occur in the second year of the program,” Kubesh says.

Burch Named AGU Fellow

Dr. James L. Burch, vice president of the SwRI Instrumentation and Space Research Division, has been elected a Fellow of the American Geophysical Union (AGU).

He received the honor in recognition of work in the field of space physics aeronomy, including research on the interaction of solar winds on the Earth’s magnetosphere and the physics of the Aurora Borealis.

Now in his first year of a two year-term as president-elect of the AGU space physics section, Burch will serve an additional two years as president. He recently served as editor-in- chief of Geophysical Research Letters, an AGU publication.

Before coming to the Institute in 1977, Burch was a NASA space physicist for six years. While participating as an investigator in a number of space flight experiments, he also achieved a prominent reputation in the fields of upper atmosphere geophysics and space plasma physics.

He holds a bachelor’s degree in physics from St. Mary’s University, a master’s degree in administration of research and development from George Washington University, and a doctorate in space science from Rice University.

Spica Spotlights the Moon

Using one of the brightest stars in the sky as a stellar flashlight, SwRI scientists got a new glimpse of the Moon’s atmosphere during a rare lunar occultation of the star Spica on April 15.

As the Moon passed between Spica and the Earth, SwRI scientists and NASA personnel at White Sands Missile Range in New Mexico successfully launched a sounding rocket carrying an Extreme Ultraviolet Spectrograph, or EUVS, to conduct the first EUVS lunar occultation experiment. The Moon’s orbit constantly changes but repeats its path approximately every eight years; therefore, an event of this kind will not be observable from the continental United States again until 2003.

Spica’s extremely high UV brightness level allowed scientists a unique opportunity to search for argon and other elements in the low density lunar atmosphere. Experiment results will help answer queries as to the atmosphere’s major components, as well as the leakage rate of radioactive decay products from the lunar interior.

“In essence, Spica acted as a probe for us,” explains SwRI’s Dr. S. Alan Stern, experiment principal investigator. “Even though Spica is 260 light years from the Moon, it provided sufficient UV light to be absorbed by a tiny, but detectable, amount of the lunar atmosphere as the Moon passed in front of the star.”

Carrying a payload that included a grazing-incidence telescope, a high-resolution EUVS, and a guidance camera, the rocket was launched at 04:07:41 MDT, less than one second after the time-critical 90-second launch window opened. A Black Brant IX launch vehicle lofted the experiment at a speed of more than 6,800 feet per second (4,500 miles per hour) to an altitude of 160 miles.

The EUVS telescope uses a unique optical system that focuses light precisely on an entrance slit, which directs the light to a spectrograph where different UV wavelengths are recorded. The components of the EUVS payload were built by SwRI and the University of Colorado Center for Astrophysics and Space Astronomy.

“The presence in Spica’s spectrum of an absorption signal at specific wavelengths within the spectrograph’s range will provide data that we can analyze to determine the abundance of certain gases in the lunar atmosphere,” says Stern.

Sloshed in Space

A scale model of a satellite fuel tank is one of four liquid motion experiment (LME) test units being developed and fabricated at Southwest Research Institute, under contract to NASA/Lewis Research Center, that will be placed onboard a space shuttle to study destabilizing fluid forces in satellite fuel tanks. In the space shuttle experiment, the tank will be spun and wobbled to simulate a range of true satellite motions. The mounting clamps on either side of the tank have ultrasensitive load cells to detect the forces imparted to the tank by the fluid.

The entire experiment (except for the laptop computer controller) must be contained inside a mid-deck locker of a space shuttle, which measures 18 inches wide by 22 inches high by 20 inches in diameter. A pedestal supports the tank platform and holds the motors that spin and wobble the table at 4 to 20 revolutions per minute about the drive pedestal axis. The “wobble axis” is tilted five degrees from the axis, imparting a motion similar to a coin spinning slowly on a tabletop. Data from the ultrasensitive load cells are transmitted to a computer via an optical data link, and flow visualization video is transmitted to a recorder through slip rings.

Launch of the LME is expected to occur in April 1996. SwRI has been involved in R&D efforts for fluid-thermal systems in space vehicles since the advent of the U.S. space program in the late 1950s. In particular, SwRI is a pioneer in the study of low-gravity sloshing and was one of the earliest investigators of propellant management devices.

Metering Research Facility Expands Services

The Gas Research Institute (GRI) Metering Research Facility (MRF, a portion of which is shown at right) located at Southwest Research Institute began expanded commercial testing March 22 in conjunction with the 3rd International Symposium on Fluid Flow Measurement held in San Antonio. More than 200 attendees toured the MRF as part of the symposium, which was organized by the North American Fluid Flow Measurement Council.

Occupying more than 10 acres of land, the MRF was developed by SwRI under GRI sponsorship to provide state-of-the-art research and testing capabilities to measure the performance of new and existing gas meters over a range of natural gas flow conditions and installation configurations of interest to the gas transmission, distribution, and production industries. The MRF provides two independent natural gas recirculating loops: a smaller, low pressure loop with test section diameters up to 6 inches, and a larger, high pressure loop capable of testing meters up to 12 inches in diameter. The facility also houses a distribution test stand for research and calibration of small, low pressure, residential and commercial gas meters.

“The MRF is available for use by anyone in the industry, including gas companies, flow meter manufacturers, and other equipment vendors who support production, transmission, and distribution operations,” says MRF Consultant William Astleford.

SwRI Opens Branch Office in Florida

Southwest Research Institute has expanded its activities in advanced training systems development by opening a branch office in Orlando, Florida.

Dr. Denise C. Varner, principal scientist in SwRI’s Training Systems and Simulators Department, Aerospace Electronics and Training Systems Division, manages the office. A psychologist specializing in advanced techniques to improve training effectiveness, she adapts human-computer interfaces — voice interfaces, advanced visual displays, graphics, and visualization tools — to fit specific training needs.

The Institute has been involved in development projects for the Naval Air Warfare Center, Training Systems Division, in Orlando since the mid 1980s. Current projects include the development and evaluation of a deployable training system for Infantry Forward Observers. Also nearing completion is the Combined Arms Staff Trainer (CAST), a planning, communications, and decision-making training tool used by the U.S. Marine Corps. Using maps, three-dimensional models of the battlefield, and a simulated communications system, CAST allows military command staff personnel to prepare, test, and refine operations in response to a variety of battlefield scenarios.

“The establishment of an office in Orlando will encourage cooperative research and technical collaboration between SwRI and such organizations as the Naval Air Warfare Center, Training Systems Division; Army Simulation, Training, and Instrumentation Command; NASA Kennedy Space Center; several Florida universities; and prime contractors and small businesses, all located in and around Orlando,” says Aerospace Electronics and Training Systems Division Vice President Walt Downing.

The address of the office is Southwest Research Institute, 12424 Research Parkway, Suite 101-6, Orlando, Florida, 32826. Dr. Varner can be reached by phone at (407) 384- 2911 or fax at (407) 282-3864.

Blaylock Elected to AIAA Board of Directors

Neil Blaylock, principal analyst in SwRI’s Materials and Structures Division, has been elected to the national board of the American Institute of Aeronautics and Astronautics (AIAA).

Blaylock will be the director of Region IV for three years and will represent AIAA members in Texas, Oklahoma, New Mexico, and Arkansas. His duties will also include membership on several national committees.

He has been an AIAA member for 15 years, serving as secretary, treasurer, vice chairman, and chairman of the Southwest Texas Section, as well as deputy director and membership chairman of Region IV. For the last two years, he has been chairman of the AIAA national membership committee.

All Shook Up

Institute engineers continue to examine ways that vibratory loading caused by seismic events such as earthquakes can affect critical equipment for the nuclear power industry. This expertise has been extended to include other applications, such as seismic loading of telecommunication equipment. The Institute’s hydraulically powered, multipurpose seismic simulator produces realistic earthquake motions in two axes simultaneously and is equipped with a 10-inch stroke that can create low frequency and high amplitude motions.

Institute engineers have used the simulator in an investigation of the hardening of telecommunications equipment through the use of type testing, in which a piece of equipment is exposed to random seismic vibrations for 30 seconds. Such investigations have clear implications for public safety during an earthquake emergency. In related programs, the Institute continues to advise regulatory agencies on seismic testing procedures to qualify critical equipment and is conducting an investigation about the responses of certain types of faulted rocks to earthquake excitations.

Published in the Summer 1995 issue of Technology Today®, published by Southwest Research Institute. For more information, contact Joe Fohn.

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