Investigation Of Flow Resistance Research Articles

Experimental Investigation on the Flow Resistance of a Staged Fuel Injector with Thermal Protection

The multistaged rotating swirling usually adopts the staged combustion and multiple point fuel supply, which has the advantages of high efficiency and low emissions. However, the high inlet temperature rise will cause autooxidation and fuel coking. Multiple fuel circuit mutual cooling technology by using different flight conditions is an effective measure for the thermal protection of the nozzle. But the complicated fuel circuit configuration inevitably increase the flow resistance in the fuel jet. This paper presents an experimental investigation of flow resistance of a triple-stage rotating swirling nozzle, concerning the effects of various factors on total pressure loss and friction factor in nozzle fuel circuit. The factors include fuel velocity V f , i , inlet temperature T f , i , and inlet Reynolds number Re f , i . The results show that the complicated fuel-cooled structure made flow resistance of the pilot fuel circuit much bigger than the main one. Meanwhile, the empirical correlations between the friction factor and the inlet Reynolds number have been fitted, which can be the reference for engineering design.

An experimental investigation of flow resistance and turbulent flow in brush fish pass

The flow and turbulence structure of a brush fish pass was investigated in a 1:2 physical model for Reynolds numbers of 5·46 × 104–1·78 × 105 and Froude numbers of 0·18–0·72. Experiments were performed with three different bed slopes (2, 4, and 6%) and four different areal bristle densities. For each bed slope and bristle density, data were collected for six different relative submergences of emergent flexible bristles. Bristle density and channel bed slope were found to play a crucial role in the experiments. From dimensional analysis and physical model measurements and calculations, the friction factor was derived for the brush fish pass. The main findings can be summarised as follows; (a) flow resistance was found to be a function of the Cauchy number of the bristles, the channel bed slope and bristle density; (b) the channel bed slope is a main parameter that controls the maximum velocity and turbulent kinetic energy (TKE) magnitudes; and (c) the spatially averaged TKE seems to be considerably lower for the same dissipated power in a brush fish pass compared with other conventional fish passes (vertical slot and natural types). Hydraulic design recommendations are given to avoid a tumbling flow regime and drag coefficient scale effects.

Experimental Investigation of Flow Resistance in a Coal Mine Ventilation Air Methane Preheated Catalytic Oxidation Reactor

This paper reports the results of experimental investigation of flow resistance in a coal mine ventilation air methane preheated catalytic oxidation reactor. The experimental system was installed at the Energy Research Institute of Shandong University of Technology. The system has been used to investigate the effects of flow rate (200 Nm3/h to 1000 Nm3/h) and catalytic oxidation bed average temperature (20°C to 560°C) within the preheated catalytic oxidation reactor. The pressure drop and resistance proportion of catalytic oxidation bed, the heat exchanger preheating section, and the heat exchanger flue gas section were measured. In addition, based on a large number of experimental data, the empirical equations of flow resistance are obtained by the least square method. It can also be used in deriving much needed data for preheated catalytic oxidation designs when employed in industry.

Investigation of flow resistance in smooth open channels using artificial neural networks

An accurate prediction of the friction coefficient is very important in hydraulic engineering since it directly affects the design of water structures, the calculation of velocity distribution, and an accurate determination of energy losses. However, conventional approaches that are profoundly based on empirical methods lack in providing high accuracy for the prediction of the friction coefficient. Consequently, new and accurate techniques are still highly demanded. This study introduces an efficient approach to estimate the friction coefficient via an artificial neural network, which is a promising computational tool in civil engineering. The estimated value of the friction coefficient is used in Manning Equation to predict the open channel flows in order to carry out a comparison between the proposed neural networks based approach and the conventional ones. Results show that the proposed approach is in good agreement with the experimental results when compared to the conventional ones.

Experimental Investigation of Flow Resistance and Wall Shear Stress in the Interior Subchannel of a Triangular Array of Parallel Rods

A simulated model of a triangular array of rods with pitch to diameter ratio of 1.1 with air flow was used to study the hydraulic parameters of the liquid metal fast breeder reactor (LMFBR) fuel geometry. The wall shear stress distribution, static pressure distribution, turbulence intensity, and friction factor were measured in the central subchannel from Reynolds numbers of 4 × 103 to 36 × 103. Our results show that the maximum wall shear stress occurs at the largest flow area, the static pressure is not uniform around the rod periphery, there is no detectable presence of secondary flow from the wall shear stress measurements, and the friction factor derived from the measured wall shear stress is less than the common friction factor derived from pressure drop measurement.