The Use of Deswirl Nozzles to Reduce the Pressure Drop in a Rotating Cavity With a Radial Inflow

1991 ◽  
Vol 113 (1) ◽  
pp. 106-114 ◽  
Author(s):  
P. R. Farthing ◽  
J. W. Chew ◽  
J. M. Owen
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Outer Part ◽  
Radial Pressure ◽  
Angular Speed ◽  
Rotating Disks ◽  
Pressure Distributions ◽  
Rotating Cavity ◽  
Predicted Values ◽  
Momentum Integral

A combined theoretical and experimental study is described in which deswirl nozzles were used to reduce the radial pressure drop in a rotating cavity with a radial inflow of air. The nozzles, which were attached to the outer part of the cavity, were angled such that the angular speed of the air at inlet could be in the opposite direction to that of the cavity. Solutions of the momentum-integral equations were used to predict the resulting radial distributions of pressure throughout the cavity. Flow visualization was used to confirm the flow structure, and transducers attached to one of the rotating disks in the cavity were used to measure the radial pressure distributions. Results are presented for “swirl fractions” (that is, the ratio of the angular speed of the air leaving the nozzles to that of the cavity) in the range −0.4 to +0.9, and for 0.01 < |Cw| Reφ−0.8 < 0.5, where Cw and Reφ are the nondimensional flow rate and rotational Reynolds number, respectively. The measured pressures are in good agreement with the predicted values, and the pressure drop across the cavity can be significantly less than that associated with solid-body rotation. The flow rate produced by the pressure drop across the cavity is not unique: There are up to three possible values of flow rate for any given value of pressure drop.

scholarly journals The Use of De-Swirl Nozzles to Reduce the Pressure Drop in a Rotating Cavity With a Radial Inflow

1989 ◽  
Author(s):  
P. R. Farthing ◽  
J. W. Chew ◽  
J. M. Owen
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Outer Part ◽  
Radial Pressure ◽  
Angular Speed ◽  
Pressure Distributions ◽  
Rotating Cavity ◽  
Predicted Values ◽  
Momentum Integral ◽  
Good Agreement

A combined theoretical and experimental study is described in which de-swirl nozzles were used to reduce the radial pressure drop in a rotating cavity with a radial inflow of air. The nozzles, which were attached to the outer part of the cavity, were angled such that the angular speed of the air at inlet could be in the opposite direction to that of the cavity. Solutions of the momentum-integral equations were used to predict the resulting radial distributions of pressure throughout the cavity. Flow visualization was used to confirm the flow structure, and transducers attached to one of the rotating discs in the cavity were used to measure the radial pressure distributions. Results are presented for ‘swirl fractions’ (that is, the ratio of the angular speed of the air leaving the nozzles to that of the cavity) in the range −0.4 to + 0.9, and for 0.01 < | CW | Reϕ−0.8 < 0.5, where CW and Reϕ, are the nondimensional flow rate and rotational Reynolds number, respectively. The measured pressures are in good agreement with the predicted values, and the pressure drop across the cavity can be significantly less than that associated with solid-body rotation. The flow rate produced by the pressure drop across the cavity is not unique: there are up to three possible values of flow rate for any given value of pressure drop.

Performance of a High-Solidity Wells Turbine for an OWC Wave Power Plant

1996 ◽  
Vol 118 (4) ◽  
pp. 263-268 ◽  
Author(s):  
L. M. C. Gato ◽  
V. Warfield ◽  
A. Thakker
Keyword(s):  
Experimental Investigation ◽  
Power Plant ◽  
Pressure Drop ◽  
Flow Rate ◽  
Aerodynamic Performance ◽  
Wave Power ◽  
Wells Turbine ◽  
Guide Vanes ◽  
Turbine Efficiency ◽  
Pressure Distributions

The paper describes an experimental investigation, and presents the results of the aerodynamic performance of a high-solidity Wells turbine for a wave power plant. A monoplane turbine of 0.6 m rotor diameter with guide vanes was built and tested. The tests were conducted in unidirectional steady airflow. Measurements taken include flow rate, pressure drop, torque, and rotational speed, as well as velocity and pressure distributions. Experimental results show that the presence of guide vanes can provide a remarkable increase in turbine efficiency.

The Use of Fins to Reduce the Pressure Drop in a Rotating Cavity With a Radial Inflow

1989 ◽  
Vol 111 (3) ◽  
pp. 349-356 ◽  
Author(s):  
J. W. Chew ◽  
P. R. Farthing ◽  
J. M. Owen ◽  
B. Stratford
Keyword(s):  
Pressure Drop ◽  
Reasonable Agreement ◽  
Numerical Solutions ◽  
Disk Model ◽  
Linear Solution ◽  
Integral Methods ◽  
Rotating Cavity ◽  
Momentum Integral ◽  
The Mathematical Model ◽  
Plane Disk

A combined theoretical and experimental study of radial inflow through a rotating cavity is reported. It is shown that radial fins attached to one of the disks are effective in reducing the pressure drop across the cavity. The mathematical model, is an extension of earlier plane-disk momentum-integral methods; the fins are treated as rectangular rib elements and a rough-disk model is derived. Numerical solutions of the integral equations are given. An approximate linear solution is also derived. Experiments were conducted when both disks were plane and when one of the disks was fitted with 60 radial fins. Flow visualization revealed the flow structure in the cavity and confirmed some of the assumptions used in the theoretical model. Measurements and predictions of the pressure drop across the cavity were in reasonable agreement.

An Analytical Model for the Incompressible Flow in Short Vortex Chambers

1969 ◽  
Vol 91 (2) ◽  
pp. 264-272 ◽  
Author(s):  
D. N. Wormley
Keyword(s):  
Static Pressure ◽  
Axisymmetric Flow ◽  
Radial Pressure ◽  
Vortex Chamber ◽  
Core Flow ◽  
Integral Analysis ◽  
Pressure Distributions ◽  
Momentum Integral ◽  
End Wall ◽  
Main Vortex

A momentum integral analysis is presented for the incompressible, steady, axisymmetric flow in a short vortex chamber of the type commonly used in vortex valves. The analysis is developed with the aid of flow visualization photographs and considers the interaction which occurs between the main vortex core flow and the viscous chamber end wall boundary layers. The radial pressure distributions predicted by the analysis compare favorably with measured end wall static pressure distributions.

Study of fluid flow through a channel deformed by piezoelement

2018 ◽  
Vol 13 (3) ◽  
pp. 1-10 ◽  
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh Nasibullaeva ◽  
O.V. Darintsev
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Flow Rate ◽  
Contact Surface ◽  
Piezoelectric Element ◽  
Neumann Boundary ◽  
Differential Pressure ◽  
Physical Parameters ◽  
Flow Through

The flow of a liquid through a tube deformed by a piezoelectric cell under a harmonic law is studied in this paper. Linear deformations are compared for the Dirichlet and Neumann boundary conditions on the contact surface of the tube and piezoelectric element. The flow of fluid through a deformed channel for two flow regimes is investigated: in a tube with one closed end due to deformation of the tube; for a tube with two open ends due to deformation of the tube and the differential pressure applied to the channel. The flow rate of the liquid is calculated as a function of the frequency of the deformations, the pressure drop and the physical parameters of the liquid.

The Departure from Equilibrium of Turbulent Boundary Layers

1968 ◽  
Vol 19 (1) ◽  
pp. 1-19 ◽  
Author(s):  
H. McDonald
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Kinetic Energy ◽  
Stress Distribution ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Momentum Integral ◽  
State Examination

SummaryRecently two authors, Nash and Goldberg, have suggested, intuitively, that the rate at which the shear stress distribution in an incompressible, two-dimensional, turbulent boundary layer would return to its equilibrium value is directly proportional to the extent of the departure from the equilibrium state. Examination of the behaviour of the integral properties of the boundary layer supports this hypothesis. In the present paper a relationship similar to the suggestion of Nash and Goldberg is derived from the local balance of the kinetic energy of the turbulence. Coupling this simple derived relationship to the boundary layer momentum and moment-of-momentum integral equations results in quite accurate predictions of the behaviour of non-equilibrium turbulent boundary layers in arbitrary adverse (given) pressure distributions.

Pressure Drop Measurements for Air Flow Through Open-Cell Aluminum Foam

2004 ◽  
Author(s):  
Nihad Dukhan ◽  
Angel Alvarez
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Flow Rate ◽  
Aluminum Foam ◽  
Flow Direction ◽  
The Other ◽  
Turbulent Regime ◽  
Thick Sample ◽  
Open Cell ◽  
Two Samples

Wind-tunnel pressure drop measurements for airflow through two samples of forty-pore-per-inch commercially available open-cell aluminum foam were undertaken. Each sample’s cross-sectional area perpendicular to the flow direction measured 10.16 cm by 24.13 cm. The thickness in the flow direction was 10.16 cm for one sample and 5.08 cm for the other. The flow rate ranged from 0.016 to 0.101 m3/s for the thick sample and from 0.025 to 0.134 m3/s for the other. The data were all in the fully turbulent regime. The pressure drop for both samples increased with increasing flow rate and followed a quadratic behavior. The permeability and the inertia coefficient showed some scatter with average values of 4.6 × 10−8 m2 and 2.9 × 10−8 m2, and 0.086 and 0.066 for the thick and the thin samples, respectively. The friction factor decayed with the Reynolds number and was weakly dependent on the Reynolds number for Reynolds number greater than 35.

Experimental and Computational Analyses of Pressure Differentials in Flexible Ducts With Different Bent Angles

2007 ◽  
Author(s):  
Ray R. Taghavi ◽  
Wonjin Jin ◽  
Mario A. Medina
Keyword(s):  
Pressure Drop ◽  
Static Pressure ◽  
Complex Geometry ◽  
Analysis Data ◽  
Secondary Flows ◽  
Low Flow ◽  
Pressure Drops ◽  
Pressure Distributions ◽  
Geometrical Effects ◽  
Cfd Analyses

A set of experimental analyses was conducted to determine static pressure drops inside non-metallic flexible, spiral wire helix core ducts, with different bent angles. In addition, Computational Fluid Dynamics (CFD) solutions were performed and verified by comparing them to the experimental data. The CFD computations were carried out to produce more systematic pressure drop information through these complex-geometry ducts. The experimental setup was constructed according to ASHRAE Standard 120-1999. Five different bent angles (0, 30, 45, 60, and 90 degrees) were tested at relatively low flow rates (11 to 89 CFM). Also, two different bent radii and duct lengths were tested to study flexible duct geometrical effects on static pressure drops. FLUENT 6.2, using RANS based two equations - RNG k-ε model, was used for the CFD analyses. The experimental and CFD results showed that larger bent angles produced larger static pressure drops in the flexible ducts. CFD analysis data were found to be in relatively good agreement with the experimental results for all bent angle cases. However, the deviations became slightly larger at higher velocity regimes and at the longer test sections. Overall, static pressure drop for longer length cases were approximately 0.01in.H2O higher when compared to shorter cases because of the increase in resistance to the flow. Also, the CFD simulations captured more pronounced static pressure drops that were produced along the sharper turns. The stronger secondary flows, which resulted from higher and lower static pressure distributions in the outer and inner surfaces, respectively, contributed to these higher pressure drops.

Simultaneous Measuring Method for Both Volumetric Flow Rates of Air-Water Mixture Using a Turbine Flowmeter

1996 ◽  
Vol 118 (1) ◽  
pp. 29-35 ◽  
Author(s):  
K. Minemura ◽  
K. Egashira ◽  
K. Ihara ◽  
H. Furuta ◽  
K. Yamamoto
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Oil Field ◽  
Liquid Density ◽  
Water Mixture ◽  
Rotor Speed ◽  
Flow Rates ◽  
Field Development ◽  
Turbine Flowmeter

A turbine flowmeter is employed in this study in connection with offshore oil field development, in order to measure simultaneously both the volumetric flow rates of air-water two-phase mixture. Though a conventional turbine flowmeter is generally used to measure the single-phase volumetric flow rate by obtaining the rotational rotor speed, the method proposed additionally reads the pressure drop across the meter. After the pressure drop and rotor speed measured are correlated as functions of the volumetric flow ratio of the air to the whole fluid and the total volumetric flow rate, both the flow rates are iteratively evaluated with the functions on the premise that the liquid density is known. The evaluated flow rates are confirmed to have adequate accuracy, and thus the applicability of the method to oil fields.

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