The trajectories of spherical particles impacting a relatively larger circular cylinder in crossflow are calculated using finite difference methods to solve the equations of motion in a Lagrangian form. Drag forces on the particles are described using an empirical correlation for the drag coefficient (as a function of Reynolds number) and the solution for steady, inviscid, incompressible flow (potential flow) around a circular cylinder. Numerical integration of the particle equations of motion is started upstream of the cylindrical target, and calculations are carried out until the particle impacts the cylinder or bypasses it completely. The effects of particle interception are neglected. Results for target efficiency and angle of impingement compare favorably with previous numerical solutions at low-particle Reynolds numbers but are found to be more accurate for free-stream velocity Reynolds numbers (Re0) > 1. In addition, results for particle velocity, angle of impact, and particle concentration are pre...

https://www.tandfonline.com/doi/pdf/10.1080/02786828808959193

Generalized Correlations for Inertial Impaction of Particles on a Circular Cylinder

Generation of aerosols in laminar flow condensers is investigated theoretically. A model is developed for simultaneous heat and vapor mass transfer, aerosol nucleation, condensation, coagulation, thermophoresis, and diffusion representing the aerosol size distribution by a lognormal function throughout the process. The importance of the above physical phenomena and the effect of process parameters (reheater and boiler temperature, seed nuclei concentration) on product aerosol characteristics (average particle size and concentration, polydispersity, and yield) and condenser length are investigated. The effects of the classical Becker-Doering and the Lothe-Pound theories for homogeneous nucleation on product aerosol characteristics are examined. Nucleation and condensation are the controlling aerosol phenomena in production of aluminum sec butoxide and dibutylphthalate aerosols in laminar flow condensers. This theory is in good agreement with theoretical and experimental results in literature.

Theory for aerosol generation in laminar flow condensers

This paper surveys the evolution of power condenser tube bundle arrangements and examines present-day designs. Condensation heat transfer during shell-side flow is reviewed, including the effects of vapor shear, condensate inundation, noncondensable gases, and enhancement techniques. The difficulties experienced in calculating vapor pressure drop through tube bundles are described, as well as recent attempts to obtain more reliable correlations. The modeling of these phenomena to predict shell-side condenser performance is reviewed, as well as the use of one- and two-dimensional computer codes. Appropriate topics for future research are identified.

Heat Transfer and Two-Phase Flow during Shell-side Condensation

Rational prediction of inertially induced particle deposition rates for a cylindrical target in a dust-laden stream☆

Theory of surface deposition from a unary dilute vapor-containing stream allowing for condensation within the laminar boundary layer☆

A simple yet rather general mathematical model is presented for predicting the distribution of condensate layer thickness when aerodynamic shear is the dominant mechanism of liquid flow along the surface. The Newtonian condensate film is treated using well-known thin-layer (lubrication theory) approximations, and condensate supply is taken to be the result of either convective diffusion or inertial impaction. Illustrative calculations for a circular cylinder in a crossflow at Re = 100,000 reveal the consequences of alternate condensate arrival mechanisms and the existence of thicker reverse-flow films behind the position of gas boundary-layer separation. The present formulation is readily generalized to include transient liquid layer flows on noncircular objects of variable surface temperature, as encountered in turbine-blade materials testing or operation.

N. Nazih-Anous

Papers

Aerodynamically-driven condensate layer thickness distributions on isothermal cylindrical surfaces