To capture the effect of initial conditions in far field evolution of momentum driven and scalar dominated flow field, Witze scaling has been used for collapsing vector and scalar data to attain asymptotic state at self-preserving region of the jet. It incorporates the initial mass, momentum, energy to capture the effect of heating level on both near and far field development of strongly heated coaxial turbulent round air jets entering into quiescent ambient. This paper compares the effectiveness of potential core length and jet effective diameter as the length scales to collapse both mean and fluctuating components of velocity vector and temperature scalar. Similarity considerations with Witze length scale using the initial momentum flux and buoyancy flux gives a good collapse at all levels of heating.

Introduction: The computational fluid dynamics (CFD) simulation of three-dimensional wire-plate electrostatic precipitator is performed in the present study. Materials and methods: The momentum equation, the electric potential equation and current continuity equation are solved by using ANSYS Fluent. The ion charge density at the corona is calculated iteratively using the Peek formula. The SIMPLE algorithm is used to treat the pressure-velocity coupling. The RNG k-ε model is used to describe turbulence. Results: The airflow keeps stable away from the first corona electrode. The distribution of the electric potential is dependent on the wire-plate distance and the wire-wire distance. The potential and ion charge density increase with the increase of the wire-plate distance. With the increase of wire-wire distance, the maximum electric field strength decreases whereas the maximum ionic charge density increases. The ion charge density near the second corona electrode is relatively small. A small wire-wire distance will make the electric field concentrated around the wires. Conclusion: According to this study, the wire-wire distance and the wire-plate distance have great effect on the distribution of ion charge density and electric field strength.

Field observations of flow measurement difficulties using portable ultrasonic flow meters are reported in this work. Accordingly, pipe wall thickness and sensors’ spacing were identified as two important sources of the in-situ flow measurement inaccuracies. Experimental tests were accomplished to evaluate the effect of input parameters on the performance of the portable ultrasonic flow meters. Iron and Unplasticized Poly Vinyl Chloride (UPVC) pipes of the outer diameters of 3, 4, and 8 inches were tested. For all tested cases, the pipe wall thickness increase would affect the ultrasonic performance more than the cases with the wall thickness decrease. A mixed effect of the sensors’ spacing was observed for the changes in pipe material/dimensions. Finally, a correction equation was proposed to improve the flow measurements.