A three-dimensional Navier-Stokes solver which utilizes a pressure based method is used to compute the incompressible flow field through the inlet guide vane (IGV) of a high Reynolds number pump. The solver has precise control of numerical dissipation through the second and fourth order artificial dissipation terms added to the momentum equations. A low-Reynolds-number form of two-equation turbulence model is used to account for the turbulence effects. Predicted blade surface static pressure distributions are in good agreement with the measurement. The tangential and radial components of the IGV wake velocity, as well as the IGV secondary flow, are predicted well. However, the predicted maximum defect in wake is larger than the measured data. Possible causes for this discrepancy are discussed. The defect in velocity in wakes at midspan is found to decay faster than the perturbation in velocity due to the secondary flow and wake in the tip region.
To analyze the earth pressure of corrugated steel culvert under high fill embankment, a field test was taken and the change law was got with the filling height increasing, the force state when geotechnical grilles were laid on the top of corrugated steel culvert was compared to that of reinforced concrete slab culvert. Results show that the pressure on the top of corrugated steel culvert is smaller than that on the external in same level when test points are near to culvert, the values of test points above and below geotechnical grilles are close, and the pressure of corrugated steel culvert is smaller than that of reinforced concrete slab culvert when filling height is above 7.3 m. So analysis indicates corrugated steel culvert spreads the upper load better, the geotechnical grille can reduce the pressure effectively through earth pressure redistribution, and the mechanical property of corrugated steel culvert is better than reinforced concrete slab culvert under high fill embankment.
A two-dimensional time-accurate Navier-Stokes solver for incompressible flows is used to simulate the effects of the axial spacing between an upstream rotor and a stator, and the wake/blade count ratio on turbomachinery unsteady flows. The code uses a pressure-based method. A low-Reynolds number two-equation turbulence model is incorporated to account for the turbulence effect. By computing cases with different spacing between an upstream rotor wake and a stator, the effect of the spacing is simulated. Wake/blade count ratio effect is simulated by varying the number of rotor wakes in one stator passage at the computational inlet plane. Results on surface pressure, unsteady velocity vectors, blade boundary layer profiles, rotor wake decay and loss coefficient for all the cases are interpreted. It is found that the unsteadiness in the stator blade passage increases with a decrease in the blade row spacing and a decrease in the wake/blade count ratio. The reduced frequency effect is dominant in the wake/blade count ratio simulation. The time averaged loss coefficient increases with a decrease in the axial blade row spacing and an increase in the wake/blade count ratio.
In this paper the technical features of various representative shipping container refrigeration units were reviewed firstly. A new type of shipping container refrigeration unit was developed. The pull-down experiment was carried out in cool mode (setpoint 0°C) and frozen mode (setpoint-18°C) using the test rig for the refrigeration unit. The experiment results shown that the new type of shipping container refrigeration unit had good pull-down performance respectively in cool mode and in frozen mode. Meanwhile, the control accuracy of the temperature of air inside container can reach ±0.3°C successfully.
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