DEPOSITION OF AEROSOL-PARTICLES IN CONTRACTION FITTINGS

Particle deposition was measured in contraction fittings with half-ang les of 12 degrees, 45 degrees, and 90 degrees. It was found that for a given contraction half angle, the losses in a contraction fitting cor relate well with the parameter Stk(1-A(o)/A(i)) where: Stk is a Pich-t ype Stokes number based on inlet velocity and outlet diameter, A, is t he outlet area, and A, is the inlet area. A correlation developed from the experimental results allows prediction of the particle losses in contraction fittings as a function of Stokes number, area ratio, and c ontraction half-angle. Test conditions on which the correlation was ba sed include a range of 0.001 less than or equal to Stk (1-A(o)/ A(i)) less than or equal to 100. Area ratios A(o)/A(i) used in the tests wer e 0.062, 0.215, and 0.571, and the test conditions encompassed Reynold s numbers based on downstream port diameter of 1120 to 58,500. The aer osol particle deposition in the contraction fitting was also modeled n umerically and the numerical results show good agreement with the expe rimental data. Flow turbulence was taken into account in the numerical work using a standard k-e closure model.