A Method for Estimating the Influence of Time-Dependent Vane and Blade Pressure Fields on Turbine Rim Seal Ingestion

2006 ◽  
Author(s):  
Bruce V. Johnson ◽  
Ralf Jakoby ◽  
Dieter E. Bohn ◽  
Didier Cunat
Keyword(s):  
Pressure Distribution ◽  
Reasonable Agreement ◽  
Present Model ◽  
Turbine Disk ◽  
Time Dependent ◽  
Cavity Pressure ◽  
Cooling Effectiveness ◽  
Pressure Distributions ◽  
Pressure Fields ◽  
Bow Wave

A method of estimating the turbine rim seal ingestion rates was developed using the time-dependent pressure distributions on the hub of turbines and a simple orifice model. Previous methods use the time-averaged pressure distribution downstream of the vanes to estimate seal ingestion. The present model uses the pressure distribution near the turbine hub, obtained from 2-D time-dependent stage calculations, and a simple-orifice model to estimate the pressure-driven ingress of gas path fluid into the turbine disk cavity and the egress of cavity fluid to the gas path. The time-dependent pressure distribution provides the influence of both the vane wakes and the bow wave from the blade on the pressure difference between hub pressure at an azimuthal location and the cavity pressure. Results from the simple-orifice model are used to determine the effective Cd that matches the cooling effectiveness at radii near the rim seal with the amount of gas-path-ingested flow required to mix with the coolant flow. Cavity ingestion data from rim-seal-ingestion experiments in a 1.5-stage turbine and numerical simulations for a 1-vane-2-blade sector of the 16 vane, 32 blade turbine were used to evaluate the method. The experiments and simulations were performed for close-spaced and wide-spaced half stages between both the vane and blade and between the blade and a trailing teardrop-shaped strut. The comparison of the model with a single Cd for axial gap seals and the experiments showed reasonable agreement for both close- and wide-spaced stages.

A Method for Estimating the Influence of Time-Dependent Vane and Blade Pressure Fields on Turbine Rim Seal Ingestion

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Bruce V. Johnson ◽  
Ralf Jakoby ◽  
Dieter E. Bohn ◽  
Didier Cunat
Keyword(s):  
Pressure Distribution ◽  
Reasonable Agreement ◽  
Present Model ◽  
Turbine Disk ◽  
Time Dependent ◽  
Cavity Pressure ◽  
Cooling Effectiveness ◽  
Pressure Distributions ◽  
Pressure Fields ◽  
Bow Wave

A method of estimating the turbine rim seal ingestion rates was developed using the time-dependent pressure distributions on the hub of turbines and a simple-orifice model. Previous methods use the time-averaged pressure distribution downstream of the vanes to estimate seal ingestion. The present model uses the pressure distribution near the turbine hub, obtained from 2D time-dependent stage calculations, and a simple-orifice model to estimate the pressure-driven ingress of gas-path fluid into the turbine disk cavity and the egress of cavity fluid to the gas path. The time-dependent pressure distribution provides the influence of both the vane wakes and the bow wave from the blade on the pressure difference between the hub pressure at an azimuthal location and the cavity pressure. Results from the simple-orifice model are used to determine the effective Cd that matches the cooling effectiveness at radii near the rim seal with the amount of gas-path-ingested flow required to mix with the coolant flow. Cavity ingestion data from rim seal ingestion experiments in a 1.5-stage turbine and numerical simulations for a 1 vane, 2-blade sector of the 16-vane, 32-blade turbine were used to evaluate the method. The experiments and simulations were performed for close-spaced and wide-spaced half stages between both the vane and blade and between the blade and a trailing teardrop-shaped strut. The comparison of the model with a single Cd for axial gap seals and the experiments showed a reasonable agreement for both close- and wide-spaced stages.

Rim Seal Ingestion Characteristics for Axial Gap Rim Seals in a Closely-Spaced Turbine Stage From a Numerical Simulation

2006 ◽  
Author(s):  
Cheng-Zhang Wang ◽  
Bruce V. Johnson ◽  
David F. Cloud ◽  
Roger E. Paolillo ◽  
T. K. Vashist ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Pressure Field ◽  
Flow Direction ◽  
Tangential Velocity ◽  
Leading Edge ◽  
Time Dependent ◽  
Flow Parameters ◽  
Pressure Fields ◽  
Bow Wave ◽  
Dependent Flow

Turbine rim seal ingestion in gas turbines is influenced by many geometric and flow parameters. For turbine stages where the vanes and blades are closely spaced, the time-dependent pressure and flow fields near the seal strongly influence the rim seal ingestion. Numerical simulations of a close-spaced configuration, similar to that used in previous experiments, were made to determine the complex 3-D, time-dependent flow and ingestion characteristics of an axial gap rim seal. The calculated pressure fields were in general agreement with previously published experimental data. The radial velocities inward and outward in the axial gap seal were appreciable fractions of the hub tangential velocity and varied with position across the airfoil pitch and the axial location in the seal. The tangential velocities in the gap varied with flow direction, generally greater than hub velocity for flow ingress and less than hub velocity for flow ingress and less than hub velocity for flow egress. Velocity jets upstream of the blade leading edge penetrated into the disk cavity approximately 10 times the seal width. The ingestion velocities for this configuration were dominated by the blade bow wave pressure field. One conclusion of the authors is that the blade pressure field can be as or more significant than the vane trailing pressure field in influencing rim seal ingestion.

scholarly journals Effect of Pressure Distribution on the Energy Dissipation of Lap Joints under Equal Pre-tension Force

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 320-328
Author(s):  
Delin Sun ◽  
Minggao Zhu
Keyword(s):  
Energy Dissipation ◽  
Pressure Distribution ◽  
Theoretical Basis ◽  
Lap Joints ◽  
Power Exponent ◽  
Lap Joint ◽  
Stick Slip ◽  
Pressure Distributions ◽  
Hysteretic Characteristics ◽  
Effective Use

Abstract In this paper, the energy dissipation in a bolted lap joint is studied using a continuum microslip model. Five contact pressure distributions compliant with the power law are considered, and all of them have equal pretension forces. The effects of different pressure distributions on the interface stick-slip transitions and hysteretic characteristics are presented. The calculation formulation of the energy dissipation is introduced. The energy dissipation results are plotted on linear and log-log coordinates to investigate the effect of the pressure distribution on the energy distribution. It is shown that the energy dissipations of the lap joints are related to the minimum pressure in the overlapped area, the size of the contact area and the value of the power exponent. The work provides a theoretical basis for further effective use of the joint energy dissipation.

scholarly journals Dynamic flight load measurements with MEMS pressure sensors

2021 ◽  
Author(s):  
Christian Raab ◽  
Kai Rohde-Brandenburger
Keyword(s):  
Pressure Distribution ◽  
Pressure Sensors ◽  
Flow Characteristics ◽  
Flight Test ◽  
Measurement Technology ◽  
Test Program ◽  
Aerodynamic Pressure ◽  
Pressure Distributions ◽  
Time Histories ◽  
Mems Pressure Sensors

AbstractThe determination of structural loads plays an important role in the certification process of new aircraft. Strain gauges are usually used to measure and monitor the structural loads encountered during the flight test program. However, a time-consuming wiring and calibration process is required to determine the forces and moments from the measured strains. Sensors based on MEMS provide an alternative way to determine loads from the measured aerodynamic pressure distribution around the structural component. Flight tests were performed with a research glider aircraft to investigate the flight loads determined with the strain based and the pressure based measurement technology. A wing glove equipped with 64 MEMS pressure sensors was developed for measuring the pressure distribution around a selected wing section. The wing shear force determined with both load determination methods were compared to each other. Several flight maneuvers with varying loads were performed during the flight test program. This paper concentrates on the evaluation of dynamic flight maneuvers including Stalls and Pull-Up Push-Over maneuvers. The effects of changes in the aerodynamic flow characteristics during the maneuver could be detected directly with the pressure sensors based on MEMS. Time histories of the measured pressure distributions and the wing shear forces are presented and discussed.

scholarly journals Influence of the Spatial Pressure Distribution of Breaking Wave Loading on the Dynamic Response of Wolf Rock Lighthouse

2021 ◽  
Vol 9 (1) ◽  
pp. 55
Author(s):  
Darshana T. Dassanayake ◽  
Alessandro Antonini ◽  
Athanasios Pappas ◽  
Alison Raby ◽  
James Mark William Brownjohn ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Pressure Distribution ◽  
Distinct Element ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Wave Loading ◽  
Wave Impact ◽  
Pressure Distributions ◽  
Impact Area ◽  
The Impact

The survivability analysis of offshore rock lighthouses requires several assumptions of the pressure distribution due to the breaking wave loading (Raby et al. (2019), Antonini et al. (2019). Due to the peculiar bathymetries and topographies of rock pinnacles, there is no dedicated formula to properly quantify the loads induced by the breaking waves on offshore rock lighthouses. Wienke’s formula (Wienke and Oumeraci (2005) was used in this study to estimate the loads, even though it was not derived for breaking waves on offshore rock lighthouses, but rather for the breaking wave loading on offshore monopiles. However, a thorough sensitivity analysis of the effects of the assumed pressure distribution has never been performed. In this paper, by means of the Wolf Rock lighthouse distinct element model, we quantified the influence of the pressure distributions on the dynamic response of the lighthouse structure. Different pressure distributions were tested, while keeping the initial wave impact area and pressure integrated force unchanged, in order to quantify the effect of different pressure distribution patterns. The pressure distributions considered in this paper showed subtle differences in the overall dynamic structure responses; however, pressure distribution #3, based on published experimental data such as Tanimoto et al. (1986) and Zhou et al. (1991) gave the largest displacements. This scenario has a triangular pressure distribution with a peak at the centroid of the impact area, which then linearly decreases to zero at the top and bottom boundaries of the impact area. The azimuthal horizontal distribution was adopted from Wienke and Oumeraci’s work (2005). The main findings of this study will be of interest not only for the assessment of rock lighthouses but also for all the cylindrical structures built on rock pinnacles or rocky coastlines (with steep foreshore slopes) and exposed to harsh breaking wave loading.

A Compact Model for Spherical Rough Contacts

2004 ◽  
Author(s):  
M. Bahrami ◽  
M. M. Yovanovich ◽  
J. R. Culham
Keyword(s):  
Pressure Distribution ◽  
Entire Range ◽  
Present Model ◽  
Numerical Solutions ◽  
Contact Radius ◽  
Bulk Deformation ◽  
Dimensional Parameters ◽  
Maximum Contact ◽  
Good Agreement ◽  
Key Parameter

The contact of rough spheres is of high interest in many tribological, thermal, and electrical fundamental analyses. Implementing the existing models is complex and requires iterative numerical solutions. In this paper a new model is presented and a general pressure distribution is proposed that encompasses the entire range of spherical rough contacts including the Hertzian limit. It is shown that the non-dimensional maximum contact pressure is the key parameter that controls the solution. Compact expressions are proposed for calculating the pressure distribution, radius of the contact area, elastic bulk deformation, and the compliance as functions of the governing non-dimensional parameters. The present model shows the same trends as those of the Greenwood and Tripp model. Correlations proposed for the contact radius and the compliance are compared with experimental data collected by others and good agreement is observed.

Airfoil Design in Subcritical and Supercritical Flows

1979 ◽  
Vol 46 (4) ◽  
pp. 761-766 ◽  
Author(s):  
W. C. Chin ◽  
D. P. Rizzetta
Keyword(s):  
Reasonable Agreement ◽  
Relaxation Method ◽  
Supercritical Pressure ◽  
Small Disturbance ◽  
Trailing Edge ◽  
Difference Analysis ◽  
Pressure Distributions ◽  
Basic Ideas ◽  
New Formulation ◽  
Supercritical Flows

The “inverse” or “design” problem in aerodynamics, which solves for the airfoil shape that induces a prescribed chordwise surface pressure subject to additional requirements on trailing edge closure, is considered in the transonic small-disturbance limit. A new formulation for the stream function ψ is suggested which uses well-set Neumann conditions on the chordwise slit, with the degree of closure dictated by a specified jump in ψ across the downstream slit emanating from the trailing edge. The boundary-value problem is solved by a type-dependent relaxation method that automatically generates closed airfoils on convergence. Computed airfoil shapes using subcritical and supercritical pressure distributions obtained from existing finite-difference analysis codes, in the latter case, with and without shockwaves, give results in reasonable agreement with the original specified shapes, and validate the basic ideas.

Determination of Three-Dimensional Body Forms from Given Pressure Distribution Over Their Surfaces

1996 ◽  
Vol 40 (01) ◽  
pp. 22-27
Author(s):  
V. M. Pashin ◽  
V. A. Bushkovsky ◽  
E. L. Amromin
Keyword(s):  
Pressure Distribution ◽  
Three Dimensional ◽  
Bodies Of Revolution ◽  
Design Constraints ◽  
Pressure Distributions ◽  
Axisymmetric Bodies

A method for solving inverse three-dimensional problems in hydromechanics is proposed which makes it possible to fit desired pressure distributions within design constraints immediately in the course of calculations. Examples of the method of application are given for bodies of revolution in flows at nonzero drift angles. These flows are not axisymmetric. Bodies of revolution in them are very handy examples of demonstrations of the method, and these examples have many technical applications.

scholarly journals A New Design Method for Centrifugal Compressor Varied Diffusers

1989 ◽  
Author(s):  
Huang Xiaoyan ◽  
Wang Qinghuan ◽  
Zhang Chao
Keyword(s):  
Centrifugal Compressor ◽  
Design Method ◽  
Numerical Technique ◽  
Flow Analysis ◽  
Computer Code ◽  
Time Dependent ◽  
Code System ◽  
Extension Method ◽  
Operating Modes ◽  
Pressure Distributions

In order to develop a CAD computer code system for centrifugal compressor, a numerical technique for design and flow analysis of vaned diffusers has been introduced in this paper. The design of diffusers has been performed by a streamline extension method. The velocity and pressure distributions at design and off-design operating modes have been calculated by a time-dependent finite difference scheme and have been corrected by boundary layer calculations. The numerical results are compared with experimental measurements, and the agreement is satisfactory.

Measurement of Seat Pressure Distributions

1987 ◽  
Vol 29 (5) ◽  
pp. 563-575 ◽  
Author(s):  
Delia Treaster ◽  
W. S. Marras
Keyword(s):  
Pressure Distribution ◽  
Video Signals ◽  
Optical Reflection ◽  
Pressure Distributions ◽  
Experimental Apparatus ◽  
Image Digitization ◽  
Novel Method ◽  
Measurement And Evaluation ◽  
Peak Pressures ◽  
Chair Design

Knowledge of seating pressures is important for proper chair design. This study demonstrates the usefulness of a new methodology for measuring pressure distributions. It refines and advances an optical-reflection technique introduced several years ago. In this way precise quantitative measures of the pressure distribution can be obtained. Video image digitization, which converts analog video signals to digital ones, provided data in a form that could be easily submitted for computer analysis. Additionally, a novel method of analysis is presented that allows for the measurement and evaluation of the distribution of seated pressures, rather than peak pressures alone. A preliminary experiment with eight subjects was conducted to demonstrate the validity of the experimental apparatus and the data treatment.

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