A Novel Hybrid Seal: Design and Experimental Validation on a High Pressure Rotordynamic Test Rig

2021 ◽  
Author(s):  
Giuseppe Vannini ◽  
Benjamin Defoy ◽  
Manjush Ganiger ◽  
Carlo Mazzali
Keyword(s):  
High Pressure ◽  
Pressure Ratio ◽  
Test Rig ◽  
Rotordynamic Coefficients ◽  
Experimental Activity ◽  
Seal Design ◽  
Piston Seal ◽  
Delivery Pressure ◽  
Inlet Swirl ◽  
Primary Focus

Abstract The design and experimental activity presented in this paper is related to a novel hybrid seal which is intended to work as a balance piston seal in an AMBs levitated high-pressure (about 300 bar delivery pressure) motor-compressor. The typical solution adopted for balance piston application is a damper seal (e.g. honeycomb seal), as the rotordynamic stability is a primary focus. However, due to interactions between the AMB controller and seal high stiffness level, the aforementioned selection is not so straightforward. After a review of the state of the art it was found that a combination of some conventional geometries (e.g. labyrinth and honeycomb) can be adopted to achieve the desired target. The design was done using a novel tool combining the validated bulk flow codes for each geometry. Moreover, a CFD analysis, based on some literature references, was carried out as a final verification of the design. The experimental activity was then performed at the Authors’ internal seal test rig. As in typical rotordynamic seal testing activity, the operating parameters leveraged to explore performance sensitivity are rotational speed, inlet pressure, pressure ratio and inlet swirl level. The outcome was satisfactory both in terms of leakage and rotordynamic coefficients.

Effect of Combustor Swirl on Transonic High Pressure Turbine Efficiency

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Paul F. Beard ◽  
Andy D. Smith ◽  
Thomas Povey
Keyword(s):  
High Pressure ◽  
Computational Study ◽  
Pressure Ratio ◽  
High Pressure Turbine ◽  
Turbine Efficiency ◽  
Baseline Case ◽  
Inlet Swirl ◽  
Computational Fluid Dynamics Cfd ◽  
External Flows ◽  
The Eu

This paper presents an experimental and computational study of the effect of inlet swirl on the efficiency of a transonic turbine stage. The efficiency penalty is approximately 1%, but it is argued that this could be recovered by correct design. There are attendant changes in capacity, work function, and stage total-to-total pressure ratio, which are discussed in detail. Experiments were performed using the unshrouded MT1 high-pressure turbine installed in the Oxford Turbine Research Facility (OTRF) (formerly at QinetiQ Farnborough): an engine scale, short duration, rotating transonic facility, in which M, Re, Tgas/Twall, and N/T01 are matched to engine conditions. The research was conducted under the EU Turbine Aero-Thermal External Flows (TATEF II) program. Turbine efficiency was experimentally determined to within bias and precision uncertainties of approximately ±1.4% and ±0.2%, respectively, to 95% confidence. The stage mass flow rate was metered upstream of the turbine nozzle, and the turbine power was measured directly using an accurate strain-gauge based torque measurement system. The turbine efficiency was measured experimentally for a condition with uniform inlet flow and a condition with pronounced inlet swirl. Full stage computational fluid dynamics (CFD) was performed using the Rolls-Royce Hydra solver. Steady and unsteady solutions were conducted for both the uniform inlet baseline case and a case with inlet swirl. The simulations are largely in agreement with the experimental results. A discussion of discrepancies is given.

scholarly journals Advanced Labyrinth Seal Design Performance for High Pressure Ratio Gas Turbines

1975 ◽  
Author(s):  
H. L. Stocker
Keyword(s):  
High Pressure ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Labyrinth Seal ◽  
Internal Cavity ◽  
Water Tunnel ◽  
High Pressure Ratio ◽  
Test And Evaluation ◽  
Seal Design ◽  
Dynamic Seal

Labyrinth seal air leakage performance in current and advanced high pressure ratio gas turbines is directly related to the limitations of current available sealing technology. Sea design technology has not kept pace with the gas turbine major component advances. Therefore, an investigation was undertaken to design, fabricate and test several unique labyrinth seal concepts intended to decrease leakage through higher efficiency. The approach used in the unique designs for improving the efficiency of labyrinth seals involved increasing the internal cavity turbulence of the seal. The program involved three test and evaluation phases: (a) water tunnel studies; (b) static air rig tests; and (c) dynamic air rig tests. The water tunnel rig provided an economical method of screening the unique candidate designs. The most promising configurations from the water rig were fabricated and tested in the static air rig. Those configurations demonstrating a significant reduction in seal leakage over current designs were tested dynamically up to 786 ft/sec in an air rig to assess the effects of rotation. The results of this program effort show that each of the unique seal designs achieved lower leakage rates than a standard baseline step seal. In addition the dynamic seal test results show minimal effect on leakage due to rotation up to 786 ft/sec.

Numerical Modeling of Rotordynamic Coefficients for Deliberately Roughened Stator Gas Annular Seals

2006 ◽  
Vol 129 (2) ◽  
pp. 424-429 ◽  
Author(s):  
Gocha Chochua ◽  
Thomas A. Soulas
Keyword(s):  
Transient Analysis ◽  
Test Rig ◽  
One Dimensional ◽  
Design And Optimization ◽  
Rotordynamic Coefficients ◽  
Seal Design ◽  
Annular Seal ◽  
Rotor Surface ◽  
Good Agreement ◽  
Annular Seals

A method is proposed for computations of rotordynamic coefficients of deliberately roughened stator gas annular seals using computational fluid dynamics. The method is based on a transient analysis with deforming mesh. Frequency-dependent direct and cross-coupled rotordynamic coefficients are determined as a response to an assigned rotor surface periodic motion. The obtained numerical results are found to be in good agreement with the available test data and one-dimensional tool predictions. The method can be used as a research tool or as a virtual annular seal test rig for seal design and optimization.

Case Study on a Complex Seal Design for a High Pressure Vessel Application

2014 ◽  
Author(s):  
Adam J. Slee ◽  
John Stobbart ◽  
David T. Gethin ◽  
Stephen J. Hardy
Keyword(s):  
High Pressure ◽  
Contact Pressure ◽  
Pressure Vessel ◽  
Plastic Material ◽  
Contact Point ◽  
Pressure Ratio ◽  
Field Application ◽  
Element Analysis ◽  
Seal Design ◽  
Metallic Seal

The results from a project to investigate the design and optimisation of a metallic seal ring as part of an end cap for a 140 tonne pressure vessel are presented. A vessel loading condition of 4483 bar (65,000 psi) internal pressure was stipulated. The design of a metallic seal of 762 mm (30″) bore diameter provided a challenging task, due to the extremely high pressure application. A detailed Finite Element Analysis (FEA) was carried out to evaluate a proposed seal and the initial conclusion was that it required complete re-design. In this work, analysis and interpretation were used to establish the modelling method for the seal. The FEA model that was developed for seal optimisation contained elasto-plastic material response, frictional contact modelling and advanced pressure field application. To maintain sealing contact pressure, the seal has to overcome differential radial deflections between the vessel and the end cap during pressure loading. The optimisation process developed a novel profiled seal contact that reduced contact stresses by 48%. This eliminated seat damage occurring during pressure loadings, whilst maintaining an adequate contact pressure ratio during a complete loading cycle. Structural deformations cause the seal contact point to shift, providing the opportunity for liquid to penetrate up to the contact point. Limitations were recognised within the FE software, which allowed unidirectional pressure penetration only. To overcome this limitation, a bespoke user subroutine was written to revise the contact algorithms within the Abaqus FE program. This enabled the model to capture ‘contact pressure zones’ to correctly progress by opening and (for the first time) close in response to seal and seat deflections.

Film-Stiffness Characterization for Supercritical CO2 Film-Riding Seals

2018 ◽  
Author(s):  
Deepak Trivedi ◽  
Rahul A. Bidkar ◽  
Chris Wolfe ◽  
Xiaoqing Zheng
Keyword(s):  
High Pressure ◽  
Test Data ◽  
Supercritical Co2 ◽  
Pressure Ratio ◽  
Fluid Film ◽  
Working Fluid ◽  
Geometrical Parameters ◽  
Cfd Model ◽  
Test Rig ◽  
Film Stiffness

Low-leakage film-riding seals are a key enabling technology for utility-scale supercritical carbon dioxide (sCO2) power cycles. Fluid film-riding rotor-stator seals (operating with sCO2 as the working fluid) are designed to track rotor movements and provide effective sealing by maintaining a tight operating clearance from the spinning rotor. The operating equilibrium clearance of the seal is determined by the balance of opening and closing forces, while the rotor tracking ability of the seal at this equilibrium gap depends on the stiffness of fluid film and its insensitivity to expected distortions of the seal and/or rotor faces. Consequently, for designing a reliable film-riding seal, it is important to characterize the fluid film stiffness and its sensitivity to equilibrium gap, pressure ratio, and seal/rotor geometrical parameters. In this paper, we describe a non-rotating experimental test rig designed for measuring the fluid film stiffness of representative seal/rotor geometries along with the instrumentation and actuation mechanisms incorporated in the test rig. The rig consists of a pressure vessel, where the top cover forms the stator portion of the seal. Inside the vessel, a non-rotating dummy rotor floats on piezo-electric actuators that precisely locate the rotor surface relative to the seal bearing surface. Several rotor and stator configurations have been fabricated and tested. The rig has three independently controlled pressure cavities (supply pressure, high pressure and low pressures) and is designed to be run with medium-pressure air and with high-pressure supercritical CO2. We present typical non-dimensionalized test data from this rig with air as the working fluid. Furthermore, we present a 3D computational fluid dynamics (CFD) model with air for predicting the film stiffness, and compare the predictions of this model with the test data acquired from the rig. The CFD model predictions for film stiffness are in excellent agreement with the test data for the two tested configurations, with the CFD-based bearing pressures overpredicting the measured bearing pressures by about 10%. Unavoidable friction in the moving rig interfaces is one of the main reasons for this mismatch. Testing on this rig with sCO2 as the working fluid and comparison with sCO2-based CFD remain as future work.

Roles of vanes in diffuser on stability of centrifugal compressor

2019 ◽  
Vol 233 (14) ◽  
pp. 5380-5392
Author(s):  
Wangzhi Zou ◽  
Xiao He ◽  
Wenchao Zhang ◽  
Zitian Niu ◽  
Xinqian Zheng
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Dynamic Pressure ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Rotating Stall ◽  
Centrifugal Compressors ◽  
Compression System ◽  
The Stability ◽  
Rotating Instability

The stability considerations of centrifugal compressors become increasingly severe with the high pressure ratios, especially in aero-engines. Diffuser is the major subcomponent of centrifugal compressor, and its performance greatly influences the stability of compressor. This paper experimentally investigates the roles of vanes in diffuser on component instability and compression system instability. High pressure ratio centrifugal compressors with and without vanes in diffuser are tested and analyzed. Rig tests are carried out to obtain the compressor performance map. Dynamic pressure measurements and relevant Fourier analysis are performed to identify complex instability phenomena in the time domain and frequency domain, including rotating instability, stall, and surge. For component instability, vanes in diffuser are capable of suppressing the emergence of rotating stall in the diffuser at full speeds, but barely affect the characteristics of rotating instability in the impeller at low and middle speeds. For compression system instability, it is shown that the use of vanes in diffuser can effectively postpone the occurrence of compression system surge at full speeds. According to the experimental results and the one-dimensional flow theory, vanes in diffuser turn the diffuser pressure rise slope more negative and thus improve the stability of compressor stage, which means lower surge mass flow rate.

Effects of Reynolds number on the performance of a high pressure-ratio turbocharger compressor

2013 ◽  
Vol 56 (6) ◽  
pp. 1361-1369 ◽  
Author(s):  
XinQian Zheng ◽  
Yun Lin ◽  
BinLin Gan ◽  
WeiLin Zhuge ◽  
YangJun Zhang
Keyword(s):  
Reynolds Number ◽  
High Pressure ◽  
Pressure Ratio ◽  
High Pressure Ratio

Rotordynamic Coefficients of Labseals for Turbines: Comparing CFD Results With Experimental Data on a Comb-Grooved Labyrinth

2005 ◽  
Author(s):  
Joachim Schettel ◽  
Martin Deckner ◽  
Klaus Kwanka ◽  
Bernd Lu¨neburg ◽  
Rainer Nordmann
Keyword(s):  
Stokes Equations ◽  
Labyrinth Seal ◽  
Navier Stokes ◽  
Test Rig ◽  
Navier Stokes Equations ◽  
Detailed Model ◽  
Identification Methods ◽  
Rotating Speed ◽  
Flow Models ◽  
Rotordynamic Coefficients

The main goal of this paper is to improve identification methods for rotordynamic coefficients of labseals for turbines. This aim was achieved in joint effort of the Technische Universita¨t Mu¨nchen, working on experimental identification methods for rotordynamic coefficients, the University of Technology, Darmstadt, working on prediction methods, and Siemens AG, realizing the results. The paper focuses on a short comb-grooved labyrinth seal. Short labseals, amongst others the above mentioned comb-grooved labyrinth, were examined. by means of a very accurately measuring test rig. The rotor was brought into statically eccentric positions relative to the stator, in order to measure the circumferential pressure distribution as a function of pressure, rotating speed and entrance swirl. The data collected were used to validate results obtained with a numerical method. The theoretical approach is based on a commercial CFD tool, which solves the Navier Stokes equations using numerical methods. As a result, a detailed model of the flow within the test rig is produced. The efforts of computation here are greater than when compared with the likewise wide-spread Bulk flow models, however improved accuracy and flexibility is expected. As the validation of the model is successful, it could then be used to gain further insight in the flow within the seal, and to understand the results better. This showed that rotordynamic coefficients of labseals gained from different test rigs are not necessarily comparable.

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