Ideal smoke meter characteristics are determined to provide a basis for evaluation of candidate systems. Five promising techniques are analyzed in detail to evaluate compilance with the practical smoke meter requirements. Four of the smoke measurement concepts are optical methods: Modulated Transmission (MODTRAN), Cross Beam Absorption Counter (CBAC), Laser Induced Incandescence (LIN), and Photoacoustic Spectroscopy (PAS). A rapid response filter instrument called a Taper Element Oscillating Microbalance (TEOM) is also evaluated. For each technique, the theoretical principles are described, the expected performance is determined, and the advantages and disadvantages are discussed The expected performance is evaluated against each of the smoke meter specifications, and the key questions for further study are given. The most promising smoke meter technique analyzed was MODTRAN, which is a variation on a direct transmission measurement. The soot-laden gas is passed through a transmission cell, and the gas pressure is modulated by a speaker.

This paper discusses some of the problems encountered in using IrRh-Ir thermocouples for measuring jet engine combustion gas temperatures up to 3500 F, such as water cooled supports and compensated lead wires. The IrRh-Ir thermocouples are subject to errors common to all immersion type probes of the sensor not attaining gas temperature such as radiation, conduction and recovery factor. Discrepancies in calculated combustion efficiency determined by IrRh-Ir and Pt Rh-Pt measured temperatures are presented and discussed. Data taken across a combustor with a unique traverse probe that featured a dual head consisting of a IrRh-Ir bare thermocouple and a A12O3 coated IrRh-Ir thermocouple is presented, compared with gas analysis and the catalytic effect offered as the most probable explanation.