scholarly journals Sealing Flow Requirements for a Rotating Disk With External Swirling Flow

1994 ◽  
Author(s):  
Michael G. Izenson ◽  
Waiter L. Swift ◽  
Ronald H. Aungier
Keyword(s):  
Swirling Flow ◽  
Tangential Velocity ◽  
Rotating Disk ◽  
External Flow ◽  
Turbine Disk ◽  
Working Fluid ◽  
Published Data ◽  
Rotating Disks ◽  
Hot Gas ◽  
Process Gas

Experiments have been performed to investigate the sealing flow requirements for a shrouded, rotating disk with external swirling flow. In some gas turbine applications, it is desirable to provide sealing flow to prevent ingress of process gas into the cavity between the turbine disk and its stator. The tangential or swirl component in flow leaving the nozzles can significantly affect the amount of flow required to seal the turbine disk. The experimental flow model used water as a working fluid and was hydrodynamically scaled to match conditions typical of hot gas expander turbines used for energy recovery in the petrochemical industry. Flow in the seal gap was observed using a stream of dye injected on the stator face near the periphery. Differential pressures were measured on the stator face and related to the observed direction of flow on the stator face. The pressures and sealing flows were normalized by the disk and gap geometry and the applied flow conditions, then compared to published data for shrouded, rotating disks with no applied, external flow. For tests where the external tangential velocity was roughly equal to twice the rim speed of the disk, sealing flow requirements were found to be 1.5 to 2.0 times greater than for a disk without the applied, external flow.

scholarly journals Effects of the rotation number on flow and heat transfer in contra-rotating disk cavity with superposed flow

2019 ◽  
Vol 11 (10) ◽  
pp. 168781401988104 ◽  
Author(s):  
Shu-xian Chen ◽  
Jing-zhou Zhang
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Rotation Number ◽  
Tangential Velocity ◽  
Inertial Force ◽  
Rotating Disk ◽  
Rotating Disks ◽  
Radial Temperature ◽  
Disk Rotation ◽  
Type Flow

The turbulent fluid flow and convective heat transfer in counter-rotating disk cavity with central axial air inflow and radial air outflow are numerically studied based on the finite volume method. Efforts are focused upon the influence of the rotation number Rt on the flow structure, cooling performance, sealing effect, and surface tangential friction characteristics in the cavity. The stagnation point where the radial outward flow along the upstream disk driven by the rotation force meets the radial outward flow along downstream disk driven by the combination of rotation force and inflow inertial force moves from upstream disk wall to the shroud with increasing Rt. At the Rt far smaller than 1, the fluids in the core region between two disks rotate with the upstream disk like a rigid body, and the tangential velocity of the rotating core decreases with the increase of the disk cavity radius, which is different from the Batchelor-type flow. At the Rt larger than 1, the fluids on the upstream disk side rotate like the Batchelor-type flow, while the sandwich rotation disappears in the fluid on the downstream disk side. The temperature on the upstream disk wall increases and then decreases with increasing values of Rt, and the critical value of Rt for the change of temperature variation is assessed to be at about Rt = 0.69. The temperature and radial temperature gradient of the downstream disk wall decrease with increasing Rt. With increasing Rt by increasing the disk rotation rate, the pressures near the downstream disk decrease, while the frictional moments on rotating disks increase. Due to the effect of flow structure, the frictional moment on the upstream disk is smaller than that on the downstream disk.

Stereo-PIV Measurements of Turbulent Swirling Flow Inside a Pipe

2020 ◽  
Author(s):  
Ayesha Almheiri ◽  
Lyes Khezzar ◽  
Mohamed Alshehhi ◽  
Saqib Salam ◽  
Afshin Goharzadeh
Keyword(s):  
Swirling Flow ◽  
Reverse Flow ◽  
Tangential Velocity ◽  
Circular Disk ◽  
Pipe Diameter ◽  
Working Fluid ◽  
Complex Flow ◽  
Mean Velocity ◽  
Radial Profiles ◽  
The Mean

Abstract Stereo-PIV is used to map turbulent strongly swirling flow inside a pipe connected to a closed recirculating system with a transparent test section of 0.6 m in length and a pipe diameter of 0.041 m. The Perspex pipe was immersed inside a water trough to reduce the effects of refraction. The working fluid was water and the Reynolds number based on the bulk average velocity inside the pipe and pipe diameter was equal to 14,450. The turbulent flow proceeds in the downstream direction and interacts with a circular disk. The measurements include instantaneous velocity vector fields and radial profiles of the mean axial, radial and tangential components of the velocity in the regions between the swirler exit and circular disk and around this later. The results for mean axial velocity show a symmetric behavior with a minimum reverse flow velocity along the centerline. As the flow developed along the pipe’s length, the intensity of the reversed flow was reduced and the intensity of the swirl decays. The mean tangential velocity exhibits a Rankine-vortex distribution and reached its maximum around half of the pipe’s radius. As the flow approaches the disk, the flow reaches stagnation and a complex flow pattern of vortices is formed. The PIV results are contrasted with LDV measurements of mean axial and tangential velocity. Good agreement is shown over the mean velocity profiles.

Prediction of Ingestion Through Turbine Rim Seals—Part 2: Externally-Induced and Combined Ingress

2009 ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Gas Turbines ◽  
Swirling Flow ◽  
Published Data ◽  
Flow Rates ◽  
Hot Gas ◽  
Predicted Values ◽  
Good Agreement

Ingress of hot gas through the rim seals of gas turbines can be modelled theoretically using the so-called orifice equations. In Part 1 (ASME GT 2009-59121) of this two-part paper, the orifice equations were derived for compressible and incompressible swirling flow, and the incompressible equations were solved for axisymmetric rotationally-induced (RI) ingress. In Part 2, the incompressible equations are solved for non-axisymmetric externally-induced (EI) ingress and for combined EI and RI ingress. The solutions show how the nondimensional ingress and egress flow rates vary with Θ0, the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. For EI ingress, a ‘saw-tooth model’ is used for the circumferential variation of pressure in the external annulus, and it is shown that ε, the sealing effectiveness, depends principally on Θ0; the theoretical variation of ε with Θ0 is similar to that found in Part 1 for RI ingress. For combined ingress, the solution of the orifice equations shows the transition from RI to EI ingress as the amplitude of the circumferential variation of pressure increases. The predicted values of ε for EI ingress are in good agreement with available experimental data, but there are insufficient published data to validate the theory for combined ingress.

Inward Flow Between Stationary and Rotating Disks

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Achhaibar Singh
Keyword(s):  
Laminar Flow ◽  
Flow Field ◽  
Velocity Distribution ◽  
Stokes Equations ◽  
Tangential Velocity ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Rotating Disks ◽  
Navier Stokes Equations

The present study predicts the flow field and the pressure distribution for a laminar flow in the gap between a stationary and a rotating disk. The fluid enters through the peripheral gap between two concentric disks and converges to the center where it discharges axially through a hole in one of the disks. Closed form expressions have been derived by simplifying the Navier– Stokes equations. The expressions predict the backflow near the rotating disk due to the effect of centrifugal force. A convection effect has been observed in the tangential velocity distribution at high throughflow Reynolds numbers.

Numerical Investigation Into Fully and Partially Wetted Disk Geometries With Relevance to Intershaft Hydraulic Seals

2020 ◽  
Author(s):  
Achinie Warusevitane ◽  
Kathy Johnson ◽  
Stephen Ambrose ◽  
Mike Walsh ◽  
Colin Young
Keyword(s):  
Fluid Dynamic ◽  
Tangential Velocity ◽  
Flow Characteristics ◽  
Rotating Disk ◽  
Radial Pressure ◽  
Experimental Investigations ◽  
Published Data ◽  
Cfd Modelling ◽  
Validation Data ◽  
Rotating Shafts

Abstract Civil aero-engines contain two or three shafts that are supported by bearings. Seals are required both between pairs of rotating shafts and between static elements and shafts. Seals located between two co/contra rotating shafts within the bearing chamber are known as intershaft seals and are typically classified as either hydraulic or oil backed. This paper focuses on research relevant to intershaft hydraulic seals. A hydraulic seal is formed by a seal fin on the inner shaft immersed in an annulus of oil in the outer shaft where the oil in the annulus is centrifuged outwards by the radial pressure gradient. Once formed a hydraulic seal does not allow air to flow across the seal and any pressure difference across the seal creates different oil levels either side of the fin. Despite their reliable operation with zero leakage, the application of hydraulic seals is restricted due to temperature limitations, oil degradation and coking. Research and development of the next generation of hydraulic seals needs to focus on addressing these issues so that the seals can be utilized in hotter zones in future engines. Understanding of the detailed fluid dynamic behaviour during hydraulic seal operation is relatively limited with very little published data. There is an acknowledged need for improved knowledge and this is the context for the current study. The ability to accurately computationally model hydraulic seals is highly desirable. Prior experimental and analytical investigations into fully and partially wetted rotating disks have been used to aid understanding of the performance and flow characteristics of hydraulic seals as there are many geometric and operational similarities. These fundamental experimental investigations in the literature provide validation data that allows the authors to establish a CFD modelling methodology. This paper initially compares the flow characteristics of a fully wetted rotating disk against experimental results available in literature including the radial and tangential velocity components. This paper subsequently investigates the flow characteristics of a partially wetted disk by examining the effect on the angular velocity of the fluid core with varying engagement and spacing ratios for two flow regimes.

scholarly journals Aerodynamic and Torque Characteristics of Enclosed Co/Counter Rotating Disks

1989 ◽  
Author(s):  
W. A. Daniels ◽  
B. V. Johnson ◽  
D. J. Graber
Keyword(s):  
Reynolds Number ◽  
Flow Direction ◽  
Rotating Disk ◽  
Frame Of Reference ◽  
Working Fluid ◽  
Rotating Disks ◽  
Total Rate ◽  
Disk System ◽  
Torque Measurements ◽  
Disk Friction

Experiments were conducted to determine the aerodynamic and torque characteristics of adjacent rotating disks enclosed in a shroud. These experiments were performed to obtain an extended data base for advanced turbine designs such as the counter-rotating turbine. Torque measurements were obtained on both disks in the rotating frame of reference for co-rotating, counter-rotating and one-rotating/one-static disk conditions. The disk models used in the experiments included disks with typical smooth turbine geometry, disks with bolts, disks with bolts and partial bolt covers and flat disks. A windage diaphragm was installed at mid-cavity for some experiments. The experiments were conducted with various amounts of coolant throughflow injected into the disk cavity from the disk hub or from the disk OD with swirl. The experiments were conducted at disk tangential Reynolds number up to 1.6×107 with air as the working fluid. The results of this investigation indicated that the static shroud contributes a significant amount to the total friction within the disk system, the torque on counter-rotating disks is essentially independent of coolant flow total rate, flow direction and tangential Reynolds number over the range of conditions tested and a static windage diaphragm reduces disk friction in counter-rotating disk systems.

Decaying Annular Swirl Flow With Inlet Solid Body Rotation

1976 ◽  
Vol 98 (1) ◽  
pp. 33-40 ◽  
Author(s):  
C. J. Scott ◽  
K. W. Bartelt
Keyword(s):  
Experimental Data ◽  
Angular Momentum ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Swirl Flow ◽  
Working Fluid ◽  
Pressure Probe ◽  
Axial Component ◽  
Profile Shape ◽  
Straight Flow

An experimental investigation of a low-speed turbulent swirling flow in a stationary, concentric, annular duct was made. The experiment involved isothermal air as the working fluid in an annulus with a diameter ratio di/d0 = 0.4, an average axial Reynolds number of 72,000, and an average axial velocity of 15 m/s. The swirl profile initially induced at the inlet was of the forced-vortex type. The rate of swirl, or the magnitude of the tangential velocity relative to the axial component, decayed axially from the inlet. Three different swirl rates were considered, one being straight flow. Extensive measurements were made of the velocity field with a cylindrical pressure probe at seven stations located 1.7 to 32.7 equivalent diameters from the entrance. The specific goals were experimental data on the axial decay of angular momentum and inferred values of the effective turbulent tangential viscosity. Results show a uniform axial decay of angular momentum and a profile shape independent of axial location. An empirical model using tangential eddy diffusivities that vary over the cross-section gave the best description of experimental data. The tangential profile shape and tangential viscosity distribution and magnitude did not depend on the initial rate of swirl.

Swirling Flow of a Viscoelastic Fluid in a Cylindrical Casing

2005 ◽  
Vol 128 (1) ◽  
pp. 88-94 ◽  
Author(s):  
Motoyuki Itoh ◽  
Masahiro Suzuki ◽  
Takahiro Moroi
Keyword(s):  
Viscoelastic Fluid ◽  
Power Law ◽  
Velocity Component ◽  
Swirling Flow ◽  
Rotating Disk ◽  
Circumferential Velocity ◽  
Working Fluid ◽  
Velocity Measurements ◽  
Aspect Ratios ◽  
Cylindrical Casing

The swirling flow of a viscoelastic fluid in a cylindrical casing is investigated experimentally, using aqueous solutions of 0.05–1.0wt.% polyacrylamide as the working fluid. The velocity measurements are made using laser Doppler anemometer. The aspect ratios H∕R (H: axial length of cylindrical casing; R: radius of rotating disk) investigated are 2.0, 1.0, and 0.3. The Reynolds numbers Re0 based on the zero shear viscosity and the disk-tip velocity are between 0.36 and 50. The velocity measurements are mainly conducted for the circumferential velocity component. The experimental velocity data are compared to the velocity profiles obtained by numerical simulations using Giesekus model and power-law model. It is revealed that at any aspect ratios tested the dimensionless circumferential velocity component Vθ′ decreases with increasing Weissenberg number We. Both the Giesekus and power-law models could predict the retardation of circumferential velocity fairly well at small We. The extent of the inverse flow region, where the fluid rotates in the direction opposite to the rotating disk, is clarified in detail.

Turbulent Viscosities for Swirling Flow in a Stationary Annulus

1973 ◽  
Vol 95 (4) ◽  
pp. 557-566 ◽  
Author(s):  
C. J. Scott ◽  
D. R. Rask
Keyword(s):  
Reynolds Number ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Outer Wall ◽  
Velocity Fields ◽  
Diameter Ratio ◽  
Working Fluid ◽  
Reduction Techniques ◽  
Annular Geometry ◽  
Tangential Momentum

Developing axial and decaying tangential velocity fields are surveyed in a stationary annulus with a nearly free vortex initial swirl distribution. Isothermal air was used as the working fluid in an annulus with a single diameter ratio (di/d0 = 0.4) and at a single axial bulk Reynolds number of 1.3 × 105. The annular geometry was selected because the inner and outer wall curvatures yield opposite effects on the swirl turbulence. The discussion is centered on a critical exposure of the data reduction techniques (momentum integrals) for obtaining the radial variations of the axial and tangential momentum diffusivities.

scholarly journals Influence of material degradation on weld seam quality in hot gas butt welding of polyamides

2021 ◽  
Author(s):  
Max Bialaschik ◽  
Volker Schöppner ◽  
Mirko Albrecht ◽  
Michael Gehde
Keyword(s):  
Weld Seam ◽  
Experimental Investigations ◽  
Heating Process ◽  
Butt Welding ◽  
Hot Gas ◽  
Process Gas ◽  
Glass Fiber Reinforced ◽  
Extrusion Welding ◽  
Different Gases

AbstractThe joining of plastics is required because component geometries are severely restricted in conventional manufacturing processes such as injection molding or extrusion. In addition to established processes such as hot plate welding, infrared welding, or vibration welding, hot gas butt welding is becoming more and more important industrially due to its advantages. The main benefits are the contactless heating process, the suitability for glass fiber reinforced, and high-temperature plastics as well as complex component geometries. However, various degradation phenomena can occur during the heating process used for economic reasons, due to the presence of oxygen in the air and to the high gas temperatures. In addition, the current patent situation suggests that welding with an oxidizing gas is not permissible depending on the material. On the other hand, however, there is experience from extrusion welding, with which long-term resistant weld seams can be produced using air. Investigations have shown that the same weld seam properties can be achieved with polypropylene using either air or nitrogen as the process gas. Experimental investigations have now been carried out on the suitability of different gases with regard to the weld seam quality when welding polyamides, which are generally regarded as more prone to oxidation. The results show that weld strengths are higher when nitrogen is used as process gas. However, equal weld strengths can be achieved with air and nitrogen when the material contains heat stabilizers.

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