A Fast-Response Calorimeter with Dynamic Corrections for Transient Heat Transfer Measurements

Shizhong Zhang,Xiaoyuan Zhang,Hong Chen,Jinping Li,Qiu Wang

doi:10.3390/app10176143

Abstract

Robust fast-response transient calorimeters with novel calorimeter elements have attracted the attention of researchers as new synthetic materials have been developed. This sensor uses diamonds as the calorimeter element, and a platinum film resistance is sputtered on the back to measure the temperature. The surface heat flux is obtained based on the calorimetric principle. The sensor has the advantages of high sensitivity and not being prone to erosion. However, non-ideal conditions, such as heat dissipation from the calorimeter element to the surroundings, can lead to measurement deviation and result in challenges for sensor miniaturization. In this study, a novel transient calorimeter (NTC) with two different sizes was developed using air or epoxy as the back-filling material. Numerical simulations were conducted to explain the complex heat exchange between the calorimeter element and its surroundings, which showed that it deviated from the assumption of an ideal calorimeter sensor. Accordingly, a dynamic correction method was proposed to compensate for the energy loss from the backside of the calorimeter element. The numerical results showed that the dynamic correction method significantly improved the measurement deviation, and the relative error was within 2.3% if the test time was smaller than 12 ms in the simulated cases. Detonation shock tunnel experiments confirmed the results of the dynamic correction method and demonstrated a practical method to obtain the dynamic correction coefficient. The accuracy and feasibility of the dynamic correction method were verified in a single detonation shock tunnel and under shock tube conditions. The NTC calorimeter exhibited good repeatability in all experiments.

Highlights

The accurate prediction of aerodynamic heating is important in the thermal and structural design of hypersonic flight vehicles, and its prediction remains a difficult problem in modern computational fluid dynamics
Much progress has been made in improving the accuracy of heat transfer measurements in recent decades, a difference of ±10% between the experimental and theoretical results is often observed, e.g., for a sharp cone standard model [1]; the difference might be even larger at certain local regions of more complex model shapes [2]
For was tested in the single detonation shock tunnel, where the test time is much longer than that of the the was tested in the single detonation shock tunnel, where the test time is much longer than that of detonation shock tunnel

Summary

Introduction

The accurate prediction of aerodynamic heating is important in the thermal and structural design of hypersonic flight vehicles, and its prediction remains a difficult problem in modern computational fluid dynamics. Much progress has been made in improving the accuracy of heat transfer measurements in recent decades, a difference of ±10% between the experimental and theoretical results is often observed, e.g., for a sharp cone standard model [1]; the difference might be even larger at certain local regions of more complex model shapes [2]. The measuring accuracy depends on the test conditions and the sensor type. It remains necessary to extensively develop new heat flux sensors and investigate the factors influencing the heat transfer measurements before further progress can be made. The development of experimental techniques has made it possible to achieve hypersonic

Results

Discussion

Conclusion