ROTATIONAL TEMPERATURE AND DENSITY MEASUREMENTS IN UNDEREXPANDED JETS AND SHOCK WAVES USING AN ELECTRON BEAM PROBE
Abstract
An electron beam probe was used to obtain measurements of rotational temperature and gas density in supersonic nitrogen jets expanding from room temperature. The parameter P(sub o)d (where P(sub o) is the stagnation pressure in torr, and d is the orifice exit diameter in mm) was varied from 15 to 480 toor-mm. This corresponds to a sonic Reynolds number range of 290 to 9,320. Density measurements were made using a photomultiplier with an interference filter centered at 3900 A and having a half-width of 100 A. The experimental density data follow the axial isentropic density distribution in regions of rotational nonequilibrium. Rotational temperature measurements were obtained from rotational spectra of the N2(+) first negative 0-0 band at 3914 A using a high dispersion spectrograph. The experimentally determined rotational temperature values follow the axial isentropic temperature distribution in a free jet down to approximately 85 K for P(sub o)d = 15 torr-mm, and 50 K for P(sub o)d = 480 torr-mm, with a scatter of about + or - 3%. Below these temperatures, the rotational temperature data depart from the isentropic curve and freeze at a constant temperature, which is dependent on the value of P(sub o)d. A shock holder was inserted in the jet and a number of shock waves in the range M = 4 to M = 15 were investigated. Density profiles through the shock waves were obtained. Rotational spectra indicate a large departure from a Boltzmann distribution in the rotational levels in the center of a shock front. This effect is small at M = 4, but very pronounced at M = 15. An apparent non- Boltzmann rotational distribution in the jet expansion flow was also observed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1966
- Accession Number
- AD0482794
Entities
People
- Paul V. Marrone
Organizations
- University of Toronto