Surface impact of seeded jets at relatively large background densities
The large inertia of heavy molecules suspended in a light carrier gas is exploited in the impingement of seeded free jets against surfaces at near-continuum conditions. It emerges that the kinetic energy at impact can be close to the free stream convective kinetic energy, even at near-continuum densities, i.e., at Knudsen numbers of 10/sup -2/ or less. Thus, one can simulate collision energies previously obtained only under molecular beam conditions but with the much higher flux densities characteristic of free jets upstream of the transition to free-molecule flow. The principal design parameter in such ''high density seeded free jet'' experiments is the heavy molecule Knudsen number, analogous to the Stokes number governing the inertial impaction of aerosol particles. When the ratio of masses m/sub p//m for the heavy and the light gases is large, the interspecies transfer of momentum and energy is rather slow, and the Stokes number is of the order of m/sub p//m times larger than the light gas Knudsen number. Thus, there is a region in which the light gas still behaves as a continuum fluid while the heavy component penetrates through it under effectively free-molecular conditions. A hydrodynamic theory capable of predicting the distribution of impact energies for such free jets impinging on solid objects at Stokes numbers of order unity is developed.
- Research Organization:
- Yale University, Mechanical Engineering, New Haven, Connecticut 06520
- OSTI ID:
- 6055255
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 82:7
- Country of Publication:
- United States
- Language:
- English
Similar Records
Validation Data Acquisition in HTTF during PCC Events
Research on thermophoretic and inertial aspects of ash particle deposition on heat exchanger surfaces in coal-fired equipment. Quarterly report No. 9, September 1, 1988--November 30, 1988