Abstract This study describes an ultrasonic velocity profiler that uses a new ultrasonic array transducer with unique 5-element configuration, with all five elements acting as transmitters and four elements as receivers. The receivers are de signed to reduce the amount of uncertainty. As the fluid moves through this setup, four Doppler frequencies are obtained. The multi-dimensional velocity information along the measurement line can be reconstructed. The transduc er has a compact geometry suitable for a wide range of applications, including narrow flow areas. The transducer’s basic frequency and sound pressure are selected and evaluated to be compatible with the application. First, to confirm the measurement ability, the measurement of the developed system in two-dimensional flow is validated by comparing it to the theoretical data. The uncertainty of measurement was within 15%. Second, the three-dimensional measurement in turbulent and swirling flow is proved experimentally to check the applicability of the proposed technique.

Abstract The flow field or multidimensional velocity distribution of the coolant in fuel rod bundles of the reactor core in pressurized water reactors (PWRs) is an important parameter that is revealed through experimental investigations. This paper presents the two-dimensional (2D) velocity profile measurement using a two-element ultrasonic transducer with both elements acting as a transceiver. The size of the transducer is minimized for compactness, leading to a narrow sound field appropriate for applications in fuel rod bundle flow. Furthermore, the transducer’s sound pressure is evaluated via simulations and experimental measurements. In order to confirm the ability of the ultra sonic velocity profiler (UVP) with a two-element transducer, the experimen tal measurement is conducted in turbulent horizontal pipe flow. The 2D ve locity vector profile is obtained, and then the measurement in swirling flow is conducted. The 2D velocity profile in an axial and radial plane is obtained utilizing the UVP measurement. Lastly, the ability of the UVP to derive the 2D velocity profile in the narrow area of the rod bundles is demonstrated.

Abstract This paper reports an experimental study on a liquid injector assembly integrated with an ultra-high frequency pulsed air jet that operates at 21 kHz. The active air-blasting assembly steadily injects a liquid through four micro-nozzles of 0.4 mm diameters each, positioned around a 1 mm nozzle through which the pulsed actuation jet flows out at supersonic velocity. High-frequency compressible air vortexes and shock waves generated by the injector atomize the liquid stream into finer droplets and distribute them to a larger area to improve mixing with the ambiance. The paper presents the design details and preliminary studies on the flow field characteristics of this novel injection scheme, which is a potential candidate for high-speed flow mixing and control applications.

Abstract This paper describes the use of particle tracking velocimetry to analyze the Lagrangian acceleration of small particles in superfluid helium with varying time increments, ∆t . The probability density of acceleration exhibits Gaussian properties for 0 ∆ <t τ , but displays a lognormal distribution for 0 τ < ∆t , where 0 τ is the migration time characterizing the particle motion. The particle trajectories are well characterized by the Hurst exponent H. For smaller time scales than 0 τ , the trajectories exhibit linear motion ( H  1), but have certain fractal properties with H  0.6 for time scales larger than 0 τ .

Abstract Background: Cardiovascular risk factors (CVRF) are very frequent in patients with chronic kidney disease (CKD) and impose a new environment to which the heart must adapt. Cardiac ultrasound is a non-invasive and easyto-perform examination that allows quantitative and qualitative assessment of the anatomy and function of the heart. The objectives of this study were to describe abnormalities observed on trans-thoracic Doppler-echocar-diography and to investigate the factors associated with them. Materials and Method: This was a monocentric retrospective cross-sectional study conducted in CKD patients hospitalized in a hospital center in Côte d'Ivoire from January 2017 to December 2018. Results: One hundred and four cases were collected with a mean age of 48.87 ± 14.47 years and a sex ratio of 1.7. Patients with end-stage-renal-disease (ESRD) represented 83.7% with 55.8% of cases of chronic glomerulonephritis. Cardiovascular risk factors were 100% anemia, 84.6% inflammatory profile, 77.9% hypertension, 76.9% hypocalcemia and in 67.3% oedema. Cardiac abnormalities were observed in 78.8% of patients. Left ventricular hypertrophy (LVH), accounting for 20.2% of cases, was associated with male gender (OR 0.127 CI 0.025 - 0.643; p = 0.013) and hypertensive nephropathy (OR 0.189 CI 0.056 - 0.637; p = 0.007). History of hypertension (OR 0.297 CI 0.084 - 1.050; p = 0.060) and diabetes (OR 5.315 CI 1.260 -22.419; p = 0.023), hypertensive nephropathy (OR 0.174 CI 0.052 - 0.585; p =0.005) and hypocalcemia (OR 6.094 CI 1.723 - 21.559; p = 0.005) are incriminated in the development of left ventricular dilatation (LVD) which accounted for 38.5% of cases. Conclusion: Left ventricular hypertrophy and dilatation are the main echocardiographic abnormalities observed in our population.