Breakup of Round Nonturbulent Liquid Jets in Gaseous Crossflow

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76074/1/AIAA-3749-644.pd

Design of a static test rig for advanced seals and air bearing testing

International audienceToday's industrial gas turbines are required to cope with strong fluctuations caused by a strongly varying feed of renewable energies into the grid. These transient operating conditions result in high temperature gradients and consequently lead to increased axial and radial displacements of turbine parts. Such flexible operations need to be supported by novel sealing technologies. This paper presents a new test facility for investigating advanced seals under 2D static conditions. It facilitates detailed experimental studies of the static pressure distribution on the seal air bearing faces, measurements on the leakage flow through the seal and measurements on the air bearing force balance. The clearance between the rotor and the seal can be set very accurately and it is furthermore possible to apply a predetermined amount of eccentricity to the seal/rotor combination

Breakup of Turbulent and Non-Turbulent Liquid jets in Gaseous Crossflows

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76872/1/AIAA-2006-1517-140.pd

Investigation of Nonbuoyant Laminar Jet Diffusion Flames: A Paradigm for Soot Processes in Turbulent Flames

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76350/1/AIAA-2004-286-942.pd

DESIGN, VALIDATION AND APPLICATION OF A RADIAL CASCADE FOR CENTRIFUGAL COMPRESSORS

ABSTRACT A novel sector test rig has been used to evaluate a new airfoil concept for multistage radial compressors. The test rig is supported by a blow-down facility where the operation conditions are adjusted by controlling mass flow, pressure and temperature. At inlet to the sector test rig itself a set of adjustable inlet guide vanes provide the test vanes with the correct inlet three-dimensional flow-field. The rig is equipped with instrumentation to allow a detailed description of the inlet and outlet conditions, as well as the blade pressure loading. This rig, using rapid prototyped vanes, allows design candidates to be screened quickly and is ideal for conducting an experimental investigation of a design space using a Design-of-Experiments approach. In this paper the rationale for the sector approach is described, the design of the test rig with 3D-CFD methods is outlined and a detailed validation of the rig is presented. For the vane in question detailed investigations of different operation points close to stall are reported, blade pressures and inlet and exit flow profiles are given. Where applicable, measurement data from the sector rig was compared to 3D-CFD calculations of the full annulus multistage configuration, to 3D-CFD calculations of the sector rig itself and to the test results from a 1.5-stage rotating test rig. The measurement data are compared to the CFD predictions and served as a calibration basis for the design tools. NOMENCLATURE INTRODUCTION In the design of industrial multistage centrifugal compressors it is sometimes desirable to redesign the stator parts without altering the impeller. Testing these designs in a full rotating test is both an expensive and time-consuming process requiring the commitment of significant resources. It would thus be advantageous to have an inexpensive and flexible test rig that could be used to screen different return channel vane designs prior to a final validation test in a rotating rig

An Experimental Investigation of the Laminar Flamelet Concept for Soot Properties

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77195/1/AIAA-2007-739-757.pd

Primary Breakup of Turbulent Round Liquid Jets in Uniform Crossflows

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77302/1/AIAA-19397-547.pd

Determination of the aerodynamic droplet breakup boundaries based on a total force approach

The determination of the critical Weg number separating the different breakup regimes has been extensively studied in several experimental and numerical works, while empirical and semi-analytical approaches have been proposed to relate the critical Weg number with the Ohl number. Nevertheless, under certain conditions, the Reg number and the density ratio ε may become important. The present work provides a simple but reliable enough methodology to determine the critical Weg number as a function of the aforementioned parameters in an effort to fill this gap in knowledge. It considers the main forces acting on the droplet (aerodynamic, surface tension and viscous) and provides a general criterion for breakup to occur but also for the transition among the different breakup regimes. In this light, the present work proposes the introduction of a new set of parameters named as Weg,eff and Cal monitored in a new breakup plane. This plane provides a direct relation between gas inertia and liquid viscosity forces, while the secondary effects of Reg number and density ratio have been embedded inside the effective Weg number (Weg,eff

Predicting droplet deformation and breakup for moderate Weber numbers

The present work examines numerically the deformation and breakup of free falling droplets subjected to a continuous cross flow. The model is based on the solution of the Navier–Stokes equations coupled with the Volume of Fluid (VOF) methodology utilized for tracking the droplet-air interface; an adaptive local grid refinement is implemented in order to decrease the required computational cost. Neglecting initially the effect of the vertical droplet motion, a 2D axisymmetric approximation is adopted to shed light on influential numerical parameters. Following that, 3D simulations are performed which include inertial, surface and gravitational forces. The model performance is assessed by comparing the results against published experimental data for the bag breakup and the sheet thinning breakup regimes. Furthermore, a parametric study reveals the model capabilities for a wider range of Weber numbers. It is proved that the model is capable of capturing qualitatively the breakup process, while the numerical parameters that best predict the experimental data are identified

Deformation and breakup of round drops and nonturbulent liquid jets in uniform crossflows.

The deformation and breakup properties of liquid drops and round liquid jets in uniform crossflows were studied computationally, motivated by applications to the behavior of sprays in crossflows found in a variety of power and propulsion systems. The objective of the present investigation was to extend the parameter range of past deformation and breakup studies, by means of numerical computations, to conditions more representative of practical high-pressure spray combustion processes. The time-dependent, incompressible and two-dimensional Navier-Stokes equations were solved on a uniform, staggered grid using the projection method of Chorin (1968) and the Level Set method of Sussman et al. (1994). Numerical simulations of the effect of crossflows on the deformation and breakup of drops and round liquid jets were carried out for the following range of parameters to study the independent effects of four dimensionless variables that fully describe the problem: Weber numbers of 0.1--2,000,000, Ohnesorge numbers of 0.001--100, Reynolds numbers of 12.5--200 and liquid/gas density ratios of 2--infinity (the last by Richardson extrapolation). The present results were in good agreement with existing measurements of deformation and breakup properties of both liquid drops and round liquid jets at large liquid/gas density ratios and with wake and drag properties of spheres and cylinders in crossflows. Similar to past experimental observations, remarkable similarities were observed between the breakup properties of round liquid jets and liquid drops. The liquid/gas density ratio was found to have a relatively small effect on deformation and breakup. Effects of Reynolds number variations were also small for conditions where the drag coefficient is relatively independent of the Reynolds number. As the Stokes flow regime is approached, however, the Weber number (We) required for breakup increases significantly due to increased drag coefficients. At large Ohnesorge number (Oh) conditions, where liquid viscous forces dominate surface tension forces, breakup is best defined in terms of a critical ratio of drag forces to liquid viscous forces, We 1/2/Oh, and plotting We1/2 /Oh vs. 1/Oh yielded breakup regime boundaries that were relatively constant for large Oh and largely independent of other parameters of the flow.Ph.D.Aerospace engineeringApplied SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/129055/2/3042034.pd