Faculty Projects
CONTROLS: AIRCRAFT AND SPACE SYSTEMS
Nonlinear Dynamics and Control Lab
Our research focuses primarily on control methods for nonlinear and coordinated control systems. Current research topics include the use of fish-like propulsive methods for locomotion and active flow control, control of coordinated systems with communication constraints, vision-based sensing for state estimation, and learning methods for nonlinear systems.
Principal Investigator: Morgansen
Autonomous Flight Systems Laboratory
The mission of the Autonomous Flight Systems Laboratory at the University of Washington is to conduct research that advances navigation, guidance and control (GN&C) technology relevant to Unmanned Aerial Vehicles (UAVs). A parallel objective is to integrate this technology into the flight mechanics and controls courses in the Department of Aeronautics and Astronautics to provide students with experience and realistic GN&C systems.
Principal Investigators: Vagners, Ly
FLUIDS/PROPULSION
Development and Implementation of Advanced Fluid Imaging Techniques
In the last couple of decades, the development of Digital Particle Image Velocimetry (DPIV) has allowed for spatial and temporal measurements by providing two-component velocities within a plane through time. Similarly, the Digital Particle Image and Thermometry Velocimetry (DPITV) has allowed for spatial and temporal measurements of velocity and temperature within a plane through time. Most recently, three-Dimensional Defocusing Particle Image Velocimetry (3DDPIV) has allowed for complete spatial and temporal measurements by providing three-component velocities within a volume. The goal of this project is to combine 3DDPIV and DPITV to allow for measurements of temperature and velocity simultaneously, within a volume, a technique which we refer to as Three Dimensional Defocusing Particle Image Thermometry and Velocimetry (3DDPITV).
Principal Investigator: Dabiri
Sponsor: NSF
Film Condensation and Evaporation
The stability and heat transfer characteristics of condensing and evaporating fluid films are studied experimentally. The high heat flux associated with phase change can be important in spacecraft thermal control. Of particular interest is how the stability characteristics of the condensing and evaporating films differ from those of films of comparable scale in the absence of phase change. The stability and heat transfer characteristics of the films are studied by optical imaging, thermal sensors, and ultrasound. Experiments involving both stable and unstable films are conducted in the laboratory.
Principal Investigator: Hermanson
Sponsor: NASA Glenn Research Center.
Microgravity Combustion
Many important turbulent combustion processes are significantly impacted by buoyancy. In this research the effects of buoyancy in turbulent diffusion flames are isolated by conducting experiments in microgravity, where the effects of buoyancy are effectively removed. The turbulent flame structure, fuel/air mixing, thermal characteristics, and exhaust emissions of both steady and pulsed turbulent flames are studied. Experiments in microgravity are conducted in the 2.2s Drop Tower at NASA Glenn Research Center. Companion experiments at normal gravity are conducted in the laboratory.
Principal Investigator: Hermanson
Sponsor: NASA Glenn Research Center.
Self-similar acceleration
Recent theoretical work has revealed that in all turbulent, self-similar flows, the vortex rotation period must be a linear function of time. It is proposed that the ratio of the current to the next rotation period determines the dissipation rate of the flow. Numerical simulations of Rayleigh-Taylor type flows in which the acceleration is a rapidly increasing function of time indicate that vortex sheet rollup is inhibited under extreme acceleration. Experiments and stability analysis are planned.
Principal Investigator: Breidenthal
Supersonic Droplets
The vaporization of liquid droplets in supersonic flow is studied experimentally. This problem has implications for the "cold start" phase of a hydrocarbon scramjet cycle, where liquid fuel can be injected into the combustion chamber. In this experiment discrete droplets are injected into a small-scale, supersonic wind tunnel. Under certain conditions it is possible to have droplets at a supersonic Mach number relative to the surrounding supersonic flow. Unheated liquid droplets can become superheated as they are injected into the relatively lower static pressure environment of a supersonic stream. This superheat in turn leads to accelerated droplet disruption and vaporization. The droplet behavior is examined using high-speed conventional and planar-laser imaging.
Principal Investigator: Hermanson
An in-tube ramjet propulsive concept is being studied whereby masses ranging from 100 gm to metric tons are accelerated to velocities as high as 8-9 km/sec . A facility has been built to explore the operating range of this device and to investigate the novel gasdynamic phenomena characteristic of this mode of propulsion. Experiments have been successfully carried out in subdetonative, transdetonative, and superdetonative propulsion modes. This technology is expected to have a number of applications in space- and ground-based missions, particularly as a hypersonic test facility.
Principal Investigator: Bruckner
Sponsors: ARO, ONR
Three-Dimensional Experimental Investigations of LES Turbulence Models
The goal of this project is to perform three-dimensional experimental studies of turbulent flow over a heated backward-facing step using 3DDPITV to investigate LES turbulence models, and perhaps develop more accurate and generally applicable models for numerical simulation based on a deeper understanding of the flow physics.
Principal Investigator: Dabiri
Sponsor: NSF
Vertical Display Case Air Curtain Optimization
This collaborative effort between UW, and Kettering University, is to study air curtains and their entrainments, as applied to vertical open display cases, which are commonly found in supermarket stores nationwide. The goal is to ascertain the conditions that would minimize ambient warm air entrainment into the cold air curtain, so as to minimize the energy consumption of the display cases. As vertical display cases are used nationwide, we will therefore be able to reduce the national energy burden in this area.
Principal Investigator: Dabiri
Sponsor: DOE & SCE
Based on a discovery in stratified entrainment, a new theory predicts that the wall fluxes will be reduced to laminar values even in a turbulent boundary layer if a sufficiently stationary and strong vortex is nearby. Water tunnel experiments have confirmed the prediction. Current research is exploring the sensitivity to freestream turbulence and the streamwise extent of the phenomenon.
Principal Investigator: Breidenthal
Spinning Detonation (in collaboration with the detonation team of Professor D. Desbordes, ENSMA, Poitiers, France)
Spinning detonation is a phenomenon where a detonation-front induced by a shock spins spontaneously in a tube. Since this is a limit of detonation, it is an area of crucial importance for safety and security. Although the phenomenon itself has been known long, the reason why the front spins is dimly understood. We are trying to pin down this mechanism by investigating from the view point of vortex dynamics.
Principal Investigator: Kurosaka
Sponsor at ENSMA: CNRS, France
Three-Dimensional Vortices
There is a special class of 3-D vortices for which exact solutions of the Navier-Stokes equations are known: for instance, Hill’s spherical vortex and O’Brien’s ellipsoidal vortices, all of which are characterized by a linear azimuthal vorticity distribution. It has comer to our attention that for this class of vortices having other geometries, exact solutions of the Navier-Stokes equations may exist, which is an objective of this research.
Principal Investigator: Kurosaka
FUSION/PLASMA SCIENCE
Plasma Science and Innovation Center (PSI-Center)
The PSI-Center refines computational tools with sufficient physics, boundary conditions, and geometry to be calibrated with experiments to achieve predictive capabilities. The Center is incorporating the physics of two-fluid/Hall effects; kinetic and FLR effects; reconnection and relaxation; transport and atomic physics; and boundary conditions into codes in a computationally tractable manner. When the predictability is sufficiently developed, the codes will be used to design improvements and upgrades to our experiments. The PSI-Center is also at the University of Wisconsin and Utah State University and it interacts with the National Laboratories and software development companies. The PSI-Center has collaborators at Caltech, University of Texas, Swarthmore, Los Alamos National Laboratory, and Lawrence Livermore National Laboratory. Data from experiments at these locations, as well as UW data will be used to validate and calibrate codes.
Principal Investigators: Jarboe, Brian Nelson, Richard Milroy and Shumlak
Sponsor: DOE
Advanced Computational Plasma Modeling (CFD Lab)
The Computational Fluid and Plasma Dynamics Laboratory has research projects that focus on developing novel computational algorithms to simulate plasma dynamics. The plasmas are modeled with the magnetohydrodynamic (MHD) model and by more physically complete two-fluid plasma models. The algorithms are implemented on parallel supercomputers using the message passing interface (MPI). The codes are applied to study computational plasma science and develop insight into plasma phenomena. Recent codes developed include a 3-D MHD code, WARP3, a co-located electrodynamics code that includes current sources, WARP4, and a full two-fluid (electron and ion) code, WARPX. The plasma simulation algorithms are based on finite volume (wave propagation) and finite element (discontinuous Galerkin) methods. Fluxes are computed with approximate Riemann solvers.
Principal Investigator: Shumlak
Sponsor: AFOSR
Flow Z-Pinch (ZaP) Project
The ZaP Flow Z-Pinch project is an innovative confinement concept to magnetically confine a high-temperature, high-density plasma. The Z-pinch has a simple, linear configuration with no applied magnetic fields. The self-field generated by the axial current confines and compresses the plasma. The concept was investigated extensively for fusion energy applications; however, the configuration is unstable to gross sausage and kink modes. The ZaP project investigates the concept of using sheared axial flows to provide complete stability without adversely affecting the advantageous properties of the Z-pinch (no applied fields, high temperatures, high densities, unity average beta, and only perpendicular heat conduction). The experiment produces a Z-pinch plasma that is 100 cm long with a 1 cm radius. The plasma exhibits stability for an extended quiescent period. The experiment addresses the basic plasma science issue of the connection between sheared flows and plasma stability. In addition, the concept has applications for fusion energy and advanced space propulsion.
Principal Investigator: Shumlak
Sponsor: DOE
Charged Nanoparticle Source Project
The Charged Nanoparticle Source Project experimentally investigates and develops a novel technique of using ultrasonic vibrations to initiate standing capillary waves in a thin film and applying a large electric field to electrostatically extract and accelerate charged droplets. The size of the droplets is controlled by the wavelength of the standing waves, which is related to the vibration frequency. The droplets are accelerated by the electric field to high velocities. The device can produce large currents of highly monodisperse electrospray. The concept is applicable to colloid thrusters, as well as, applying thin coats of material onto composites for electrostatic shielding, UV protection, and fire retardant installation.
Principal Investigator: Shumlak
Sponsor: Boeing
Free Flight Probe
In a hot, long lived magnetized plasma the internal magnetic field is the most important quantity to know and the most difficult to measure. In this diagnostic development program, a small, Faraday rotating projectile when fired through the plasma causes the polarization of a laser beam to rotate in proportion to the local magnetic field. Because of the short time in the plasma and a diamond coating neither the plasma nor the probe are damaged during the time of measurement.
Principal Investigator: Jarboe
Sponsor: AFOSR
Collaboration with the Princeton Plasma Physics Laboratory (PPPL) on NSTX
Collaboration with PPPL is being carried out to apply and to study plasma startup and sustainment using helicity injection technology initially developed in the HIT program at the UW. Coaxial electrodes are used to inject helicity into a major fusion facility, the National Spherical Torus Experiment (NSTX). Reconnection and relaxation then form and sustain the confining magnetic fields. We have achieved the world record for non-inductive current startup. We plan to continue to apply new understanding and technology to large experiments at the national laboratories as it is developed at UW.
Principal Investigator: Jarboe
Sponsor: DOE
Helicity Injected Torus (HIT) Program
One of the most difficult problems in magnetically confined controlled fusion is sustaining the plasma current while the 100 million degree plasma is being confined. The HIT program is attacking this problem by applying and studying helicity injection current drive. The longest lived constraint for the motion of a magnetized plasma is magnetic helicity (flux self linkage). The helicity is stored in the magnetic field and the current increases as the helicity is increased. This method of current drive is two orders of magnitude more efficient than the more established methods of particle injection and rf wave injection. Presently, at the UW, the method is being applied inductively to an economically attractive concept call the spheromak.
Principal Investigator: Jarboe
Sponsor: DOE
Plasma Propulsion Experiment (PPX)
PPX is a student built facility that can test and diagnose various plasma accelerators for space propulsion applications. Currently, a pulsed plasma thruster (PPT) is being tested. The thruster plasma plume is being analyzed with a time-of-flight diagnsotic combined with a gridded-energy analyzer. The combined data is analyzed with a simulate annealing technique to determine ionized species concentrations, as well as, plume temperatures and exhaust velocities. Previous investigations have focused on a Hall thruster optimization. Hall thrusters operate by generating an azimuthal current by the Hall effect that can very efficiently accelerate a plasma to high exhaust velocities.
Principal Investigator: Shumlak
Sponsor: DOD
“We're tackling some of the most challenging and fascinating problems of flight, spaceflight, and energetics.”