Stephen Whitmore

Dr. Stephen Whitmore

Mechanical and Aerospace Engineering, Utah State University, Logan, Utah, USA
orcid
Guest editor for MDPI Green propellants Special Edition

Research Focus & Metrics

Academic Career Length

48Years (1979-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 May 2013 in Journal of Propulsion and Power
Verified
Journal Article
Closed access
Stephen WhitmoreStephen Whitmore
Stephen Whitmore
ZPZachary W. Peterson
Zachary W. Peterson
SEShannon D. Eilers
Shannon D. Eilers

1 November 2015 in Journal of Propulsion and Power
Verified
Journal Article
Closed access
Stephen WhitmoreStephen Whitmore
Stephen Whitmore
SWSean D. Walker
Sean D. Walker
DMDaniel P. Merkley
Daniel P. Merkley
MSMansour Sobbi
Mansour Sobbi
Results from a development campaign, where modern additive manufacturing methods are used to fabricate hybrid rocket fuel grains with embedded helical ports, are presented. The fuel grains were constructed from acrlyonitrile butadiene styrene using commercially available three-dimensional printer feedstock material. Gaseous oxygen is used as the oxidizer for this test campaign. When compared to cylindrical fuel ports, significant increases in fuel regression rates were observed, and these increases in regression rate diminished with time as the helical fuel port burns to become progressively more cylindrical. Comparisons to the helical pipe flow skin friction correlation developed by Mishra and Gupta indicate that increased skin friction only partially accounts for the increased regression rate. The Mishra–Gupta correlation underpredicts the regression rate amplification early in the fuel burn and overpredicts that value late in the burn. The authors conclude that radial wall-blowing due to fuel pyrolysis is suppressed by centrifugal forces introduced by the helical flow and compresses the boundary-layer flame zone closer to the fuel port wall. Thus, convective heat transfer is significantly enhanced, and that effect also contributes significantly to the observed regression rate increase. This effect diminishes with time and is not modeled by the Mishra–Gupta correlation.

12 January 1998
Verified
Conference Paper
Closed access
Stephen WhitmoreStephen Whitmore
Stephen Whitmore
BCBrent Cobleigh
Brent Cobleigh
JHJr. Edward Haering
Jr. Edward Haering

1 November 1998 in AIAA Journal
Verified
Journal Article
Closed access
TRThomas J. Rohloff
Thomas J. Rohloff
Stephen WhitmoreStephen Whitmore
Stephen Whitmore
ICIvan Catton
Ivan Catton

1 November 2015 in Journal of Propulsion and Power
Verified
Journal Article
Closed access
Stephen WhitmoreStephen Whitmore
Stephen Whitmore
NINathan R. Inkley
Nathan R. Inkley
DMDaniel P. Merkley
Daniel P. Merkley
MJMichael I. Judson
Michael I. Judson
This paper details the development of a new ignition system concept that circumvents many of the difficulties associated with the current state of the art for hybrid rocket ignition systems. The technology is based on the unique electrical breakdown properties of additively manufactured acrylonitrile butadiene styrene. Strategic application of an electric field across the top of an additively manufactured acrylonitrile butadiene styrene fuel grain induces an electrostatic arc along the horizontally stacked manufactured surface features, and results in a small amount of pyrolyzed fuel vapor. When this event occurs simultaneous with the introduction of an oxidizing flow, the ablated hydrocarbon vapor together with residual energy from the electrical arc rapidly seeds combustion. Multiple incremental prototype systems were designed, built, and tested. Best conditions for successful operation were discovered, including minimum ignition pressure, optimal geometry, and electrical power requirements. An embedded ignitor design demonstrated “hands-off” restart capability using a lab-scale 75-mm-diam hybrid motor. The system was restarted up to a dozen consecutive times with no propellant changeover or replenishment.

1 May 1999 in Journal of Aircraft
Verified
Journal Article
Closed access
TRThomas J. Rohloff
Thomas J. Rohloff
Stephen WhitmoreStephen Whitmore
Stephen Whitmore
ICIvan Catton
Ivan Catton