Verification of sequential function specification method with intermittent spray cooling

Abstract

Intermittent spray cooling (ISC) is an active flow control technique that is used to provide rapid response and increase the spray efficiency. The transient feature of surface heat flux and temperature is important for the understanding of ISC performance. It is also a sensitive parameter in the implementation of the control strategy of ISC. In this study, a sequential-function-specification method (SFSM) was used to determine the time-varying surface heat flux from an internal temperature measurement in ISC. The simulated heat flux input was used to evaluate the accuracy of the method while considering regularization, random noise, size of the time step and pulse period in the simulation. Experiments were conducted and the results were compared with the simulation results to examine a detailed characteristic of surface heat flux calculation. Regularization dampens random noise but induces deterministic bias. Increasing the time step and decreasing the pulse period result in high deterministic bias. The standard deviation of these estimates decreases as the time step increases. The present study gives a concise insight into the parameter effect of SFSM in ISC, offering guidance to select the appropriate parameter of SFSM and proper experimental settings.