摘要
A host of authors have proposed some theoretical and experimental formulas in hydromechanics concerning the calculation of the drag coefficient Cd of spherical bodies. But all of the existing Cd formulas hold true only at small Reynolds numbers and are restricted within certain flowing range.As regards the fall velocity ω of spherical bodies, there is yet no formula applicable to each flowing range and to a direct expression and calculation of the fall velocity ω.In view of these, from N-S equations, and meanwhile based on measured data and complicated calculations, the author has developed and proposed the following results:(1) The drag coefficient (2) The dimensionless fall velocity where Es, Ω* and constants etc. are indicated in detail in this paper.Through laborious calculation in lgRe<5 larger range, the verification proves that our results well agree with the measured data. And the leading features of formulas of this paper are: (1) simple in form, (2) convenient for general use, (3) preferable on the part of the precision and applicability.Finally, to introduce this process and to illustrate the temperature effects on the fall velocity ω, some examples are discussed in this paper.
A host of authors have proposed some theoretical and experimental formulas in hydromechanics concerning the calculation of the drag coefficient Cd of spherical bodies. But all of the existing Cd formulas hold true only at small Reynolds numbers and are restricted within certain flowing range.As regards the fall velocity ω of spherical bodies, there is yet no formula applicable to each flowing range and to a direct expression and calculation of the fall velocity ω.In view of these, from N-S equations, and meanwhile based on measured data and complicated calculations, the author has developed and proposed the following results:(1) The drag coefficient (2) The dimensionless fall velocity where Es, Ω* and constants etc. are indicated in detail in this paper.Through laborious calculation in lgRe<5 larger range, the verification proves that our results well agree with the measured data. And the leading features of formulas of this paper are: (1) simple in form, (2) convenient for general use, (3) preferable on the part of the precision and applicability.Finally, to introduce this process and to illustrate the temperature effects on the fall velocity ω, some examples are discussed in this paper.