A Design Tool for Aerodynamic Lens Systems - Department of ...

More documents

Recommendations

Info

FIG. 10. Particle transmission efficiency as a function of the Stokes number for various Reynolds numbers at three different subsonic Mach numbers. (a) Ma = 0.03; (b) Ma = 0.10; (c) Ma = 0.32. A DESIGN TOOL FOR AERODYNAMIC LENS SYSTEMS 329 FIG. 11. Cutoff Stokes numbers as a function of Reynolds number for three different Mach numbers. lens corresponding to the limiting trajectory of particle loss to the downstream spacer is ri = ds,i/(2ηc,i). The transmission efficiency can be estimated as the ratio of particle flux within ri to the total flux in that stage. Therefore, ηt, spacer, i = ⎧ ⎪⎨ 1 for dB,i ≤ ds,i ⎪⎩ for dB,i > ds,i . [24] � � d 2 � � s,i d 4 s,i 2 ds,i−1η − c,i ds,i−1ηc,i � � dB,i−1 2 � � dB,i−1 4 2 d − s,i−1 ds,i−1 Note that dB,i = dB,i−1 ×|ηc,i|, and the diffusion effect is neglected. Loss by diffusion at each stage can be estimated through the Gormley-Kennedy equation (Gormley and Kennedy 1949): ηt, GK, i = ⎧ ⎨1 − 5.50 ξ ⎩ 2/3 + 3.77ξ for ξ
330 X. WANG AND P. H. MCMURRY DESCRIPTION OF THE “LENS CALCULATOR” A Microsoft Excel spreadsheet serves as a user interface for the Lens Calculator. The detailed calculations are done in the background by a program written in Visual Basic. The calculator has two modules: lens design and lens test. The lens design module designs lens dimensions and operating conditions for user specified parameters. The lens test module estimates the FIG. 12. Flow chart for the aerodynamic lens design module. performance for a lens system with specified dimensions and operating conditions. Figure 12 shows the flow chart of the lens design module. The design process starts with reading in the user input information of carrier gas, several operating parameters, particle density, and the focusing size range. Then the program calculates the operating pressure and dimensions of the lens system (orifice
Page 1 and 2: Aerosol Science and Technology, 40:
Page 3 and 4: 322 X. WANG AND P. H. MCMURRY aReyn
Page 5 and 6: 324 X. WANG AND P. H. MCMURRY Furth
Page 7 and 8: 326 X. WANG AND P. H. MCMURRY lens
Page 9: 328 X. WANG AND P. H. MCMURRY TABLE
Page 13 and 14: 332 X. WANG AND P. H. MCMURRY the p
Page 15: 334 X. WANG AND P. H. MCMURRY Gidwa

A Design Tool for Aerodynamic Lens Systems - Department of ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?