# THERMAL EFFECT ON MASS FLOW-RATE OF SONIC NOZZLE

## Main Article Content

## Abstract

Sonic nozzles are widely used as flow measurement and transfer standard. The thermal effect of sonic nozzle is significant at low Reynolds number. It includes two correction factors, C_{T} for the thermal boundary layer and C_{α} for constrained thermal deformation of throat area. Firstly, using the similarity solution, the formula for correction factor C_{T} over wall temperature range from 0.8T_{0} to 1.2T_{0} was obtained. For γ = 1.33, C_{T} = 1 - 3.800Re^{-1/2}ΔT/T_{0}; for γ = 1.4, C_{T} = 1 - 3.845Re^{-1/2}ΔT/T_{0}; for γ = 1.67, C_{T} = 1 - 4.010Re^{-1/2}ΔT/T_{0}. Secondly, thermal and stress models for partially constrained expansion were built. Unlike the free expansion, truth slopes of C_{α} for three nozzles are +1.74×10^{-6}, -2.75×10^{-5} and -3.61×10^{-5}, respectively. Lastly, the experimental data of copper nozzle was used to validate present results. It revealed that modified experimental values are in good agreement with the present result.

## Article Details

**Thermal Science**, [S.l.], mar. 2017. ISSN 2334-7163. Available at: <http://thermal-science.tech/journal/index.php/thsci/article/view/2228>. Date accessed: 23 june 2017. doi: https://doi.org/10.2298/TSCI151104146D.

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Accepted 2017-03-13

Published 2017-03-13

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