Stability of an Axial-Thrust Self-Balancing System

2012 ◽  
Author(s):  
Takashi Shimura ◽  
Satoshi Kawasaki ◽  
Masaharu Uchiumi ◽  
Toshiya Kimura ◽  
Mitsuaki Hayashi ◽  
...  
Keyword(s):  
High Speed ◽  
Rocket Engine ◽  
Axial Direction ◽  
Small Radius ◽  
Axial Vibration ◽  
Axial Thrust ◽  
Balance System ◽  
Delivery Pressure ◽  
Rotor Assembly ◽  
Outlet Orifice

Rocket pump is characterized by high speed and high delivery pressure. Therefore, balancing of axial thrust acting on the rotor assembly is one of the most important factors. To realize complete axial thrust balancing, a balance piston-type axial-thrust self-balancing system is often used in rocket pumps. Such a system is comprised of an inlet orifice (#1) located at the outlet part of the impeller, outlet orifice (#2) located at the small-radius position of the back shroud and a chamber between these two orifices. Those orifices made by edges of the casing and the impeller shroud look like rings. The rotor assembly is allowed to move axially less than 1 mm to control the clearances of the orifices. The rotor assembly moves toward the turbine part when unbalanced axial thrust is imposed on the rotor assembly in the direction from the inlet of the pump toward the turbine part. As a result, the clearance of the inlet orifice increases and that of the outlet orifice decreases. This results in an increase in the pressure in the chamber between the orifices and makes the axial thrust generated by the balance piston in the direction from the turbine part toward the inlet of the pump increase. In this way, unbalance axial thrust imposed on the rotor assembly can be compensated automatically. This axial thrust balance system acts dynamically as if it is a mass and spring system although there is no mechanical spring. Too much vibration in the axial direction causes metal to metal rubbing, resulting in the explosion of rocket turbopumps. Although large amplitude axial vibration has been observed in rocket engine turbopumps, the cause of the vibration has not yet been clarified. In the present study, the self-balancing system was modeled by combining the mechanical structure and the fluid system in a calculation program. Stability of the system was investigated using this program. Effects of geometry, fluids, etc., were examined and methods to stabilize the system in order to suppress the axial vibration were developed.

Stability of an Axial Thrust Self-Balancing System

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Takashi Shimura ◽  
Satoshi Kawasaki ◽  
Masaharu Uchiumi ◽  
Toshiya Kimura ◽  
Mitsuaki Hayashi ◽  
...  
Keyword(s):  
Large Amplitude ◽  
High Speed ◽  
System Analysis ◽  
Axial Direction ◽  
Radial Pressure ◽  
Liquid Hydrogen ◽  
Axial Vibration ◽  
Axial Thrust ◽  
Balance System ◽  
Excited Vibration

Rocket pumps are characterized by high speed and high delivery pressure. Therefore, balancing of axial thrust acting on the rotor assembly is one of the most important factors. To realize complete axial thrust balancing, a balance piston-type axial-thrust self-balancing system is often used in rocket pumps. This axial thrust balance system acts dynamically as if it were a mass and spring system, although there is no mechanical spring. Sometimes, large amplitude axial vibration is observed in a liquid hydrogen turbopump. Too much vibration in the axial direction causes metal-to-metal rubbing, resulting in fatal accidents of rocket turbopumps. However, the cause of the vibration has not yet been clarified. In the present study, the self-balancing system was modeled by combining the mechanical structure and the fluid system in a calculation program of one-dimensional multidomain system analysis software. Stability of the system was investigated using this program and the possibility of existence of self-excited vibration was confirmed. Effects of geometry, fluids, viscous damping, radial pressure drop in the chamber, and orifice flow coefficients on the stability of the balance piston system were examined. As a result, it was concluded that large compressibility of liquid hydrogen was the cause of the large amplitude axial vibrations. With the results of analyses, methods to stabilize the system in order to suppress the axial vibration were suggested.

scholarly journals The Influence of the Axial Rub Added in the Radial Rub on the Wear of the Seal Fins during the High Speed Rub of Labyrinth-Honeycomb Seal

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1997
Author(s):  
Bin Lu ◽  
Haijun Xuan ◽  
Xiaojian Ma ◽  
Fangjun Han ◽  
Weirong Hong ◽  
...  
Keyword(s):  
Wear Rate ◽  
High Speed ◽  
State Of The Art ◽  
Negative Influence ◽  
Axial Thrust ◽  
Cross Sectional ◽  
Honeycomb Seal ◽  
Aero Engine ◽  
Honeycomb Seals ◽  
Clearance Change

Labyrinth-honeycomb seals are a state-of-the-art sealing technology commonly used in aero-engine interstage seal. The undesirable severe rub between the seal fins and the honeycomb due to the clearance change may induce the cracking of the seal fins. A pervious study investigated the wear of the seal fins at different radial incursion rates. However, due to the axial thrust and mounting clearance, the axial rub between the seal fins and the honeycomb may occur. Hence, this paper focuses on the influence of the axial rub added in the radial rub on the wear of the seal fins. The rub tests results, including rubbing forces and temperature, wear rate, worn morphology, cross-sectional morphology and energy dispersive spectroscopy results, are presented and discussed. Overall, the participation of the axial rub leads to higher rubbing forces, temperature, and wear rate. The tribo-layer on the seal fin is thicker and the cracks are more obvious at high axial incursion rate. These phenomena indicate the axial rub has a negative influence on the wear of the seal fins and should be avoided.

Characterization of Rotating Cavitation in a High Speed Inducer of Liquid Rocket Engine

2011 ◽  
Vol 320 ◽  
pp. 196-201
Author(s):  
Fei Tang ◽  
Li Jia Wen
Keyword(s):  
High Speed ◽  
High Performance ◽  
Rocket Engine ◽  
Liquid Rocket Engine ◽  
Blade Surface ◽  
Cavitation Phenomenon ◽  
Flow Fluctuations ◽  
Blade Cascade ◽  
Liquid Rocket

Rotating cavitation is one of the most important problems in the development of modern high performance rocket pump inducers. In this paper, a numerical simulation of rotating cavitation phenomenon in a 2D blade cascade of liquid rocket engine inducer was carried out using a mixture model based on Rayleigh-Plesset equation. The purpose is to investigate the characterization of rotating cavitation in a high speed inducer. The results show that when sub-synchronous rotating cavitation occurs, the speed for the length of the blade surface cavitation is lower than the speed frequency of rotation shaft with the same direction. The external aspect is that the pressure at the upstream of blades changes synchronous. Thus, the generation of sub-synchronous rotating cavitation is closely related to the changes of flow angel which caused by the flow fluctuations. Hence, elimination of the flow rate redistribution among the flow channel can effectively suppress the occurrence of this phenomenon.

Turbine Nozzle Endwall Phantom Cooling With Compound Angled Pressure Side Injection

2018 ◽  
Author(s):  
Kevin Liu ◽  
Hongzhou Xu ◽  
Michael Fox
Keyword(s):  
Film Cooling ◽  
High Speed ◽  
Axial Direction ◽  
Secondary Flows ◽  
Test Case ◽  
Pressure Side ◽  
Complex Flow ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Extended Area

Cooling of the turbine nozzle endwall is challenging due to its complex flow field involving strong secondary flows. Increasingly-effective cooling schemes are required to meet the higher turbine inlet temperatures required by today’s gas turbine applications. Therefore, in order to cool the endwall surface near the pressure side of the airfoil and the trailing edge extended area, the spent cooling air from the airfoil film cooling and pressure side discharge slots, referred to as “phantom cooling” is utilized. This paper studies the effect of compound angled pressure side injection on nozzle endwall surface. The measurements were conducted in a high speed linear cascade, which consists of three nozzle vanes and four flow passages. Two nozzle test models with a similar film cooling design were investigated, one with an axial pressure side film cooling row and trailing edge slots; the other with the same cooling features but with compound angled injection, aiming at the test endwall. Phantom cooling effectiveness on the endwall was measured using a Pressure Sensitive Paint (PSP) technique through the mass transfer analogy. Two-dimensional phantom cooling effectiveness distributions on the endwall surface are presented for four MFR (Mass Flow Ratio) values in each test case. Then the phantom cooling effectiveness distributions are pitchwise-averaged along the axial direction and comparisons were made to show the effect of the compound angled injection. The results indicated that the endwall phantom cooling effectiveness increases with the MFR significantly. A compound angle of the pressure side slots also enhanced the endwall phantom cooling significantly. For combined injections, the phantom cooling effectiveness is much higher than the pressure side slots injection only in the endwall downstream extended area.

Prototype Design of a High-Speed Viscous Air Spindle

2008 ◽  
Author(s):  
Guido M. J. Delhaes ◽  
Anton van Beek ◽  
Ron A. J. van Ostayen ◽  
Robert H. Munnig Schmidt
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Axial Direction ◽  
Cylindrical Part ◽  
Traction Forces ◽  
Micro Cutting ◽  
Tool Holder ◽  
Air Spindle ◽  
Prototype Design

In this paper an innovative air driven spindle for micro cutting applications is presented. The spindle uses a viscous traction concept which has the advantage that the viscous traction forces can act directly on the cylindrical part of the tool, which makes the tool-holder redundant. Furthermore, the tool can be actuated in the axial direction within the housing. In this paper the concept of the viscous turbine, a design of a prototype spindle along with the traction and load-capacity of the spindle are discussed.

Tilt-Wing Rotorcraft Dynamic Analysis Using Multibody Formulation

1992 ◽  
Author(s):  
Patrick J. O’Heron ◽  
Parviz E. Nikravesh ◽  
Ara Arabyan ◽  
Donald L. Kunz
Keyword(s):  
Flight Control ◽  
High Speed ◽  
Equations Of Motion ◽  
Flight Path ◽  
Minimal Set ◽  
Near Wake ◽  
Highly Nonlinear ◽  
Nonlinear Transient ◽  
Nonlinear Transient Dynamics ◽  
Rotor Assembly

Abstract A model is presented that can be used to simulate the highly nonlinear transient dynamics associated with advanced rotorcraft conversion processes. Multibody equations of motion of the fuselage, the tilting wing, and the rotor assembly are derived using a minimal set of coordinates. An enhanced aerodynamics model is employed to account for unsteadiness and nonlinearity in the near-wake aerodynamics, with a dynamic uniform inflow to compute the far-wake aerodynamics, and a flight control system is employed to compute the blade pitch settings that are necessary to achieve a desired flight path. The model is subjected to a demanding flight path simulation to illustrate that it can perform vertical take-off, hover, tilt-wing conversion, and high-speed forward flight maneuvers effectively.

Rotation-induced axial oscillation of a composite nanoconvertor at low temperature

2020 ◽  
pp. 107754632093711
Author(s):  
Bo Song ◽  
Kun Cai ◽  
Jiao Shi ◽  
Qing-Hua Qin
Keyword(s):  
Molecular Dynamics ◽  
Low Temperature ◽  
Large Amplitude ◽  
Oscillation Amplitude ◽  
Axial Direction ◽  
Axial Vibration ◽  
Axial Oscillation ◽  
Axial Translation ◽  
Vibration Responses ◽  
Dynamics Simulations

We propose a model of a nanostructure which can transform an input rotation into an output oscillation. In the model, the rotor has two identical internally hydrogenated deformable parts. The mechanism is that the rotation-induced centrifugal force and van der Waals force drive the recoverable deformation of the hydrogenated deformable parts, which gives rise to the axial translation of the free end of the rotor. Once the two hydrogenated deformable parts deform periodically, the free end of the rotor oscillates periodically in the axial direction. Molecular dynamics simulations are conducted to reveal the dynamic response of the system at low temperature. Four main types of deformation and the first three orders of vibration responses of the hydrogenated deformable parts are analyzed. Synchronous breathing vibration of the two hydrogenated deformable parts produces ideal oscillation with large amplitude. Asynchronous axial vibration of the hydrogenated deformable parts reduces the oscillation amplitude or produces beat vibration. The way to control the amplitude of the axial oscillation/vibration is given.

scholarly journals Axial thrust behavior in LOX-pump of rocket engine

1994 ◽  
Vol 10 (2) ◽  
pp. 244-250 ◽  
Author(s):  
Junichi Kurokawa ◽  
Kenjiro Kamijo ◽  
Takashi Shimura
Keyword(s):  
Rocket Engine ◽  
Axial Thrust

Entropy production analysis for the clocking effect between inducer and impeller in a high-speed centrifugal pump

2019 ◽  
Vol 233 (15) ◽  
pp. 5302-5315 ◽  
Author(s):  
Baofeng Yang ◽  
Bin Li ◽  
Hui Chen ◽  
Zhanyi Liu
Keyword(s):  
Entropy Production ◽  
Centrifugal Pump ◽  
High Speed ◽  
Rocket Engine ◽  
Leading Edge ◽  
Entropy Production Rate ◽  
Pump Efficiency ◽  
Impeller Blade ◽  
Turbulent Dissipation ◽  
Production Analysis

The clocking effect between the inducer and the impeller has a certain impact on the performance of the high-speed centrifugal pump, which however, is often ignored by designers. In the present study, three-dimensional numerical simulation based on Reynolds-averaged Navier–Stokes method is adopted to evaluate the influence of this clocking effect on the performance of a full-scale liquid rocket engine oxygen turbopump. A novel entropy production method with the correction of wall effects was introduced to evaluate the energy loss generated in the pump and to clarify the formation mechanism of this clocking effect from the perspective of the second law of thermodynamics. Results show that the best performance is captured when the relative circumferential angle between the inducer blade trailing edge and the impeller blade leading edge was set as 0° and the maximum difference in pump efficiency is approximately 1.5% at different clocking positions. The entropy production analysis of each component of the pump reveals that the clocking effect on the pump performance mainly originates from the turbulent dissipation in the impeller and the diffuser. The study of the local entropy production rate and the streamline distributions shows that the formation of this clocking effect is owing to the different extent of the separation vortices in the impeller passage near the shroud and the impeller blade wake in the diffuser inlet as well as the backflow vortices in the diffuser blade passage near the volute tongue.

Submicrometre particle separation via high-speed gas centrifuges

1997 ◽  
Vol 211 (1) ◽  
pp. 17-29 ◽  
Author(s):  
A Hitchings ◽  
T O'Doherty ◽  
N Syred
Keyword(s):  
High Speed ◽  
Relative Effectiveness ◽  
Present System ◽  
Particle Sizing ◽  
Air Bearings ◽  
Axial Thrust ◽  
Foil Bearings ◽  
Large Size ◽  
System Operating ◽  
Regeneration Systems

The separation of submicrometre particulate matter from gases is a problem that has attracted much interest over the years. Filter systems require low face velocities and hence tend to be of large size, while also requiring sophisticated, bulky, regeneration systems. A high-speed centrifuge which can be linked with a turbocharger has been developed which can remove particulates well into the submicrometre range in diameter. The centrifuge operates at speeds of up to 60 000 r/min, with the assistance of both axial thrust air bearings and radial foil bearings. Experimental analysis of the centrifuge using particle sizing techniques etc. has shown the effectiveness of the system operating at a range of different flowrates. This has been done by comparing the relative effectiveness of the system for the different flowrates. The paper discusses the analysis of the separative efficiency (i.e. the ability to concentrate particles into a small proportion of the gas) of the present system and the predicted efficiencies of future systems.

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