Dynamics and stability of lean-premixed swirl-stabilized combustion

Advanced models of fuel droplet heating and evaporation

This paper addresses the physiochemical mechanisms involved in transcritical and supercritical vaporization, mixing, and combustion processes in contemporary liquid-fueled propulsion and power-generation systems. Fundamental investigation into these phenomena poses an array of challenges due to the obstacles in conducting experimental measurements and numerical simulations at scales sufficient to resolve the underlying processes. In addition to all of the classical problems for multiphase chemically reacting flows, a unique set of problems arises from the introduction of thermodynamic nonidealities and transport anomalies. The situation becomes even more complex with increasing pressure because of an inherent increase in the flow Reynolds number and difficulties that arise when fluid states approach the critical mixing condition. The paper attempts to provide an overview of recent advances in theoretical modeling and numerical simulation of this subject. A variety of liquid propellants, including hydrocarbon and cryogenic fluids, under both steady and oscillatory conditions, are treated systematically. Emphasis is placed on the development of a hierarchical approach and its associated difficulties. Results from representative studies are presented to lend insight into the intricate nature of the problem.

http://www.yang.gatech.edu/publications/Journal/P%26C(2000,%20ref19,%20Yang).pdf

Modeling of supercritical vaporization, mixing, and combustion processes in liquid-fueled propulsion systems

Modeling of turbulent dilute spray combustion

A Level Set Method for vaporizing two-phase flows

Numerical analysis of convecting, vaporizing fuel droplet with variable properties

Interacting, convecting, vaporizing fuel droplets with variable properties

Axisymmetric calculations of three-droplet interactions

Computational blood flow studies are providing an increasingly important complement to clinical experiments in 21st century biomedical engineering. Motivated by probing deeper into this topic, a theoretical and numerical study is presented of the flow induced by an impulsive acceleration to steady state hemodynamics in a curved tube which is investigated as a boundary layer developing with time from the curved entrance to a straight tube (blood vessel). The transient processes are simulated with a finite volume method solution of the Navier–Stokes equations. The rapid growth of the boundary layer with the core flow is captured in the curved entrance, along the tube to an axisymmetric flow in the downstream. Secondary flow patterns, centrifugal pressures and total head contours are correlated with longitudinal velocity distributions across various sections. It is observed that the entrance zone is controlled by uniform inlet velocity and centrifugal forces. The high pressure drop in the onset flow is associated with strong acceleration which is comparable to generating systolic pressures. The simulations further indicate that a sustained increment in volumetric flow rate is necessary to maintain the pressure wave in the aorta. Furthermore, the velocity distributions are shown to approach Hagen–Poiseuille flow in the downstream zone. The complex hemodynamic characteristics are visualized effectively with computational simulations and the study demonstrates the excellent ability of this approach in elaborating critical flow details in aortic hemodynamics. 

C.H. Chiang

Papers

Numerical analysis of convecting, vaporizing fuel droplet with variable properties

Interacting, convecting, vaporizing fuel droplets with variable properties

Axisymmetric calculations of three-droplet interactions

Computation of Three-Dimensional Blood Flow Development in a 180° Curved Tube Geometry