Pulsed Thruster Thrust Stand Measurement Evaluations
Abstract
This paper presents a numerical analysis of thrust stand response during pulsed thruster operation. The system model incorporates an underdamped displacement-type thrust stand under a periodic, impulsive load. Analytic and numerical methods are used to examine thrust stand measurement characteristics during simulated operation. Displacement oscillation characteristics as a function of damping coefficient (alpha) and the ratio (tau) between the time between thruster impulses and thrust stand natural period are presented. The effects of simulated thrust stand random displacement signal noise were quantified for a=0.3 with tau varying from 0.1 to 0.7. These results show that measurement uncertainty due to noise decreases when tau is increased. An analytic expression relating average thrust and average thrust stand displacement was derived. Using this expression, the effect of time-dependent, random thruster impulse variability was examined. Numerical simulations were used to estimate the dependence of thrust measurement uncertainty on the number of impulses used for averaging. These results also showed that measurement uncertainty due to impulse bit variability decreased when tau is increased. Integration of 10 impulses is adequate to achieve measurement uncertainty below 2% for a random 10% impulse bit variation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 13, 1998
- Accession Number
- ADA408664
Entities
People
- G. G. Spanjers
- J. H. Schilling
- Keith A. Mcfall
Organizations
- Air Force Research Laboratory