Thermal effect on body temperature distribution of the critical flow Venturi nozzle

•Experiments conducted by a multipoint temperature acquisition system.•Steady temperature distributions and dynamic temperature of CFVNs body.•Isotherm maps of CFVN body obtained by the Kriging interpolation method.•CFD simulation for the effect of the shock on the body temperature distribution of CFVN.•Streamline, shock structure in fluid region and isotherm, heatline in solid region.

The expansion of the gas through a critical flow Venturi nozzle (CFVN) leads to a 50 °C temperature drop of the gas at the nozzle throat. The body of CFVN is also cooled, which produces several effects on the flow characteristics called thermal effects. Thus, there is an urgent necessary to investigate the dynamic temperature distribution of CFVN body. Firstly, experiments were conducted by a multipoint temperature acquisition system. The dynamic temperatures of 12 sampling points for each stainless steel CFVN were obtained. It is found that the dynamic response time of CFVN body temperature can be hundreds to thousands of seconds. The maximum body temperature drop of 16.5 °C was observed. Then some isotherm maps of CFVN body were obtained by the Kriging interpolation method. Finally, CFD simulations were carried out to explain the experimental results because the flow field of axisymmetric nozzle is difficult to be observed. The results revealed the position of shock wave is the main influence on body temperature distribution of CFVN. All the results can be used to further analyze the thermal effect of CFVN.