超临界流体换热可视化实验研究进展

Near the critical point, supercritical fluids exhibit dramatic variations in physical properties, leading to complex flow and heat transfer behaviors essential for energy and chemical system design. Recent experimental advances in flow visualization for supercritical convective heat transfer are systematically reviewed.The principles, applications, and limitations of key techniques including particle image velocimetry （PIV）, schlieren imaging, laser Doppler velocimetry （LDV ）, interferometry, neutron imaging, and inelastic X-ray scattering are emphatically analyzed. Research results show that neutron imaging and inelastic X-ray scattering can capture the multiphase-like features of liquid-like and gas-like coexistence in the pseudo-critical region. Although PIV and LDV provide high-resolution velocity data, their accuracy is limited under sharp property gradients due to refractive index distortions and poor tracer particle responsiveness. Schlieren imaging is found to provide qualitative density and temperature field visualization, and its potential for quantitative velocity measurements can be realized when combined with other methods.Interferometry enables quantitative, high-spatiotemporal-resolution measurements of local temperature and density, proving effective for probing heat transfer mechanisms.Future work should prioritize the development of interference-resistant, high-precision visualization techniques, the improvement of distortion correction via deep learning, the advancement of multimodal integration, and the strengthening of experiment-simulation synergies to elucidate fundamental mechanisms of supercritical flow and heat transfer.