Interior Spectroscopic Investigation of the Propellant Energy Modes in an Arcjet Nozzle
Abstract : Internal emission spectroscopy measurements were performed in the nozzle expansion region of a 26 kW class ammonia arcjet. A series of three optical access ports (0.020-inch diameter) were equally spaced along the center line of the expansion nozzle. Atomic and ionic excitation temperatures of H and NII were determined through the use of Boltzmann plots. Electron density measurements were also taken based upon Stark broadening of the hydrogen beta Balmer transition. It is believed that a change in the mechanism governing the electron density occurred just downstream of the constrictor between the first two access ports lending evidence that arc attachment is occurring in this region. Although the trends for excitation temperatures and electron density were similar to those previously observed in 1 kW arcjets, the temperature values were found to be significantly less. In addition, vibrational and rotational temperatures of NH were measured and appeared to be frozen throughout the expansion nozzle.
Coherent anti-Stokes Raman scattering velocity and translational temperature measurements in resistojets.
Coherent anti-Stokes Raman scattering is demonstrated as a quantitative diagnostic in low-density flows by mapping H(2) velocity and translational temperature inside and outside the nozzle of a resistojet. A spatial resolution of better than 35 mum along the flow direction and 350 mum transverse to it was attained in a density as low as 5 x 10(15) cm(-3). The accuracy of the velocity, inferred from the Doppler shift of the Q (1) Raman resonance, was limited by the scan linearity of the laser to +/-0.2 km/s. Translational temperatures, inferred from linewidths and complicated by saturation and ac Stark effects, had an accuracy of ~20%. A discussion of applicability to molecular nitrogen is presented.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.