The homogeneous field measurement of internal flow and spray of internal combustion engine injector nozzles under high pressure has always been one of the difficulties in experimental research. In this paper, an actual-size aluminum alloy nozzle is designed, and the simultaneous measurement of internal flow and near-field spray is successfully realized with the help of synchrotron radiation X-ray phase contrast imaging technology under an injection pressure of 30~90 MPa. For a 0.25 mm aperture nozzle, different radii of the inlet corner can induce different cavitation layer thicknesses, and the measured flow section shrinkage ratio is 0.70. The flow characteristics in the nozzle are entirely connected to the jet characteristics, indicating a tight correlation between internal flow and jet morphology. Finally, the internal cavitation of the nozzle was studied by the CFD simulation, and the simulation results are in good agreement with the experiment.

Cavitation in the microchannel can affect the flow characteristics and cause corrosion damage to the microchannel. Quantitative vapor concentration characteristics inside the microchannel are a prerequisite for understanding the cavitation characteristics in microfluidics and cavitation simulation prediction. In this paper, high-speed visible-light imaging at the nanosecond timescale and micrometer spatial scale was used to study the vapor concentration in microchannels. The steady-state image was discretized from sub-millisecond scale (200 μs) to nanosecond scale images (20 ns) based on the equivalent same exposure time. The occurrence probabilities of the vapor and liquid phases at each pixel position can be calculated by means of proper segmentation of the vapor and liquid phases in the nanosecond cavitation images. The quantitative measurement of vapor-phase concentration in steady-state flow in a microfluidic channel was successfully realized with the accumulation of vapor-phase probability of nanosecond images. Vapor-phase concentrations of 0–100% can be effectively distinguished by this method, and the mixed flow characteristics of two cavitations can be quantified. In addition, the cavitation concentration mapped from the steady-state grayscale image was compared with the results of quantitative concentration measurements.

Radiant porous burners are favored in household and industrial applications for their high flexibility, minimal emissions, and excellent fuel adaptability. Enhancing heating temperature uniformity improves the heat transfer efficiency and heating quality. This work presents a two-dimensional numerical study on the non-uniformity of the heating temperature (i.e., solid temperature at the burner exit) in a cylindrical porous burner. The root mean square (RMS) of the heating temperature ($T_{\mathrm{s},\mathrm{rms}}$) is used to quantify the non-uniformity. From the numerical results, the cylindrical porous burner exhibits a non-uniform heating temperature and a non-uniform mass flow rate of flue gas at the sub-outlets. The surface emissivity and equivalence ratio have minor effects on the $T_{\mathrm{s},\mathrm{rms}}$. However, increasing the volumetric flow rate and solid temperature leads to a more uniform distribution of heating temperature. The $T_{\mathrm{s},\mathrm{rms}}$ decreases from 40 K to 4.4 K as the volumetric flow rate increases from 26.75 slm (standard liters per minute) to 87 slm at an equivalence ratio of 0.96 and emissivity of 0.85. Meanwhile, the results demonstrate that increasing the thermal conductivity of the porous shell improves the heating temperature uniformity. This study presents guidelines for enhancing the uniformity of heating temperature for the cylindrical porous burner.