scholarly journals Numerical Analysis of Cavitation Instabilities In Inducer Blade Cascade

2005 ◽  
Author(s):  
Benoiˆt Pouffary ◽  
Regiane Fortes Patella ◽  
Jean-Luc Reboud
Keyword(s):  
Flow Rate ◽  
Rocket Engine ◽  
Suction Side ◽  
Cavitation Number ◽  
Vapor Mixture ◽  
Cavitation Model ◽  
Flow Parameters ◽  
Blade Cascade ◽  
Cavitation Behavior ◽  
Unsteady Behavior

The cavitation behavior of a four-blade rocket engine turbopump inducer was simulated by the CFD code Fine/TurboTM. The code was modified to take into account a cavitation model based on a homogeneous approach of cavitation, coupled with a barotropic state law for the liquid/vapor mixture [1–4]. In the present study, the numerical model of unsteady cavitation was applied to a four-blade cascade drawn from the inducer geometry. Unsteady behavior of cavitation sheets attached to the inducer blade suction side depends on the flow rate and cavitation number σ. Numerical simulations of the transient evolution of cavitation on the blade cascade were performed for nominal flow rate and different cavitation numbers, taking into account simultaneously the four blade-to-blade channels. Depending on the flow parameters, steady or unsteady behaviors spontaneously take place. In unsteady cases, sub synchronous or super synchronous regimes were observed. Some mechanisms responsible for the development of these instabilities are proposed and discussed.

scholarly journals Numerical Analysis of Cavitation Instabilities in Inducer Blade Cascade

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Benoît Pouffary ◽  
Regiane Fortes Patella ◽  
Jean-Luc Reboud ◽  
Pierre-Alain Lambert
Keyword(s):  
Flow Rate ◽  
Rocket Engine ◽  
Suction Side ◽  
Cavitation Number ◽  
Vapor Mixture ◽  
Cavitation Model ◽  
Flow Parameters ◽  
Blade Cascade ◽  
Computational Fluid Dynamics Cfd ◽  
Cavitation Behavior

The cavitation behavior of a four-blade rocket engine turbopump inducer was simulated by the computational fluid dynamics (CFD) code FINE∕TURBO™. The code was modified to take into account a cavitation model based on a homogeneous approach of cavitation, coupled with a barotropic state law for the liquid∕vapor mixture. In the present study, the numerical model of unsteady cavitation was applied to a four-blade cascade drawn from the inducer geometry. Unsteady behavior of cavitation sheets attached to the inducer blade suction side depends on the flow rate and cavitation number σ. Numerical simulations of the transient evolution of cavitation on the blade cascade were performed for the nominal flow rate and different cavitation numbers, taking into account simultaneously the four blade-to-blade channels. Depending on the flow parameters, steady or unsteady behaviors spontaneously take place. In unsteady cases, subsynchronous or supersynchronous regimes were observed. Some mechanisms responsible for the development of these instabilities are proposed and discussed.

A Study of Cavitation Flow in a Centrifugal Pump at Part Load Conditions Based on Numerical Analysis

2012 ◽  
Author(s):  
Jianping Yuan ◽  
Yanxia Fu ◽  
Shouqi Yuan
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Suction Side ◽  
Cavitation Number ◽  
Flow Coefficient ◽  
Inlet Pipe ◽  
Part Load ◽  
Cavitation Inception ◽  
Wide Range ◽  
Load Conditions

In order to predict cavitation performance of the centrifugal pump, including cavitating structures and vapour volume at the blade suction side, as well as its relationship with the backflow in the impeller eye, a 3D numerical simulation of detailed steady and unsteady cavitating flow was applied to reproduce its inner flow fields at part load conditions (0.5Qd and 0.4Qd). The comparisons of cavitation characteristics of the current centrifugal pump at an on-design point (1.0Qd) and a high flow rate (1.2Qd) were achieved as well. In addition, Frequency analysis of pressure fluctuations at the blade passages and the inlet pipe were also obtained during cavitation for a flow coefficient of 50%. The results further show that successive blade cavitation patterns and the creeping cavitation number dropping appear for a wide range of flow rates when the inlet total pressure decreases from cavitation inception to the breakdown of the centrifugal pump, as is quite different from that when cavitation occurs at 1.0Qd or 1.2Qd. Unbalanced attached cavities on the blade suction side were also observed at 0.5Qd. Meanwhile, the unsteady behaviour of cavities attached to the blade suction side and cavitation number dropping depend on the flow rate and cavitation number. Another significant characteristic of the phenomenon is that all the domain frequencies in blade passages and inlet pipe at part load conditions are 0.048Hz∼48.285Hz, which is typically lower than the shaft rotational frequency of the model centrifugal pump.

scholarly journals Numerical Model to Predict Unsteady Cavitating Flow Behavior in Inducer Blade Cascades

2006 ◽  
Vol 129 (2) ◽  
pp. 128-135 ◽  
Author(s):  
R. Fortes-Patella ◽  
O. Coutier-Delgosha ◽  
J. Perrin ◽  
J. L. Reboud
Keyword(s):  
Numerical Model ◽  
Flow Behavior ◽  
Rocket Engine ◽  
Simple Algorithm ◽  
Suction Side ◽  
Correction Method ◽  
Numerical Resolution ◽  
Finite Volume Discretization ◽  
Cavitation Behavior ◽  
Unsteady Cavitating Flow

The cavitation behavior of a four-blade rocket engine turbopump inducer is simulated. A two-dimensional numerical model of unsteady cavitation was applied to a blade cascade drawn from an inducer geometry. The physical model is based on a homogeneous approach of cavitation, coupled with a barotropic state law for the liquid/vapor mixture. The numerical resolution uses a pressure-correction method derived from the SIMPLE algorithm and a finite volume discretization. Unsteady behavior of sheet cavities attached to the blade suction side depends on the flow rate and cavitation number. Two different unstable configurations of cavitation are identified. The mechanisms that are responsible for these unstable behaviors are discussed, and the stress fluctuations induced on the blade by cavitation instabilities are estimated.

scholarly journals Influence of the Blade Number on Inducer Cavitating Behavior

2009 ◽  
Author(s):  
O. Coutier-Delgosha ◽  
G. Caignaert ◽  
G. Bois ◽  
J.-B. Leroux ◽  
Patrick Olivier ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rocket Engine ◽  
Cavitation Number ◽  
Design Flow ◽  
Flow Rates ◽  
Blade Number ◽  
Radial Forces ◽  
Critical Cavitation

Effects of the blade number on the performance of a rocket engine turbopump inducer are investigated in the present paper. For that purpose, two inducers characterized by three blades and five blades respectively were manufactured and tested experimentally. The two inducers were designed on the basis of identical design flow rate, and identical pressure elevation at nominal flow rate. The first part of the study focuses on the steady behavior of the inducers in cavitating conditions: evolutions of performance, torque, mass flow rate, and amplitude of radial forces on the shaft according to the inlet pressure are considered. Several flow rates and rotation speeds are investigated. Significant differences between the inducers are obtained concerning the critical cavitation number, the amplitude of the radial forces, and the organization of cavitation in the machinery. Cavitation instabilities are investigated in the second part of the study. Various flow patterns are detected according to the mass flow rate and the cavitation number.

scholarly journals Influence of the Blade Number on Inducer Cavitating Behavior

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
O. Coutier-Delgosha ◽  
G. Caignaert ◽  
G. Bois ◽  
J.-B. Leroux
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rocket Engine ◽  
Cavitation Number ◽  
Design Flow ◽  
Flow Rates ◽  
Blade Number ◽  
Radial Forces ◽  
Critical Cavitation

Effects of the blade number on the performance of a rocket engine turbopump inducer are investigated in the present paper. For that purpose, two inducers characterized by three blades and five blades, respectively, were manufactured and tested experimentally. The two inducers were designed on the basis of identical design flow rate and identical pressure elevation at nominal flow rate. The first part of the study focuses on the steady behavior of the inducers in cavitating conditions: evolutions of performance, torque, mass flow rate, and amplitude of radial forces on the shaft according to the inlet pressure are considered. Several flow rates and rotation speeds are investigated. Significant differences between the inducers are obtained concerning the critical cavitation number, the amplitude of the radial forces, and the organization of cavitation in the machinery. Cavitation instabilities are investigated in the second part of the study. Various flow patterns are detected according to the mass flow rate and the cavitation number.

Numerical Simulation of Cavitating Flow in a Francis Turbine

2008 ◽  
Author(s):  
Lingjiu Zhou ◽  
Zhengwei Wang ◽  
Yongyao Luo ◽  
Guangjie Peng
Keyword(s):  
Numerical Simulation ◽  
Transport Equation ◽  
Flow Rate ◽  
Suction Side ◽  
Cavitating Flow ◽  
Francis Turbine ◽  
Efficiency Change ◽  
Experiment Data ◽  
Calculation Results ◽  
Vapor Fraction

The 3-D unsteady Reynolds averaged Navier-tokes equations based on the pseudo-homogeneous flow theory and a vapor fraction transport-equation that accounts for non-condensable gas are solved to simulate cavitating flow in a Francis turbine. The calculation results agreed with experiment data reasonably. With the decrease of the Thoma number, the cavity first appears near the centre of the hub. At this stage the flow rate and the efficiency change little. Then the cavity near the centre of the hub grows thick and the cavities also appear on the blade suction side near outlet. With further reduce of the Thoma number the cavitation extends to the whole flow path, which causes flow rate and efficiency decrease rapidly.

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.

Critical Suction Peformance Test of Turbopump Assembly for a Liquid-Propellant Rocket Engine

2018 ◽  
Author(s):  
Hang Gi Lee ◽  
Ju Hyun Shin ◽  
Suk Hwan Yoon ◽  
Dae Jin Kim ◽  
Jun Hwan Bae ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Performance Test ◽  
Rocket Engine ◽  
Lightweight Design ◽  
Cavitation Number ◽  
Inlet Pressure ◽  
Liquid Oxygen ◽  
Pump Failure ◽  
Critical Cavitation ◽  
Suction Performance

This study investigates the behavior of a turbopump assembly during critical cavitation of the propellant pumps in the upper rocket engine of the Korea Space Launch Vehicle-II. Turbopumps operate under conditions involving low pressure at the pump inlet and high rotational speeds to allow for a lightweight design. This severe environment can easily cause cavitation to occur in the pump. This cavitation can then cause the pump operation to fail. As the cavitation number in the pump decreases below the critical point, the pump fails to operate. There is concern regarding the behavior of the turbopump assembly arising from pump failure due to cavitation. It is necessary to verify the problems that may occur if the turbopump assembly operates under extreme conditions, such like the critical cavitation. This study performed tests to investigate the breakdown of pumps in the turbopump assembly. Tests were conducted with liquid nitrogen, water, and high-pressure air instead of the mediums used during actual operation of liquid oxygen, kerosene, and hot gas. The turbopump was tested at the design point of 27,000 rpm, while the inlet pressure of each pump was controlled to approach the critical cavitation number. The turbine power output was maintained during the tests. The results show that the breakdown point of the oxidizer pump using liquid nitrogen, which is a cryogenic medium, occurred at a lower cavitation number than during an individual component suction performance test using water. The fuel pump using water, meanwhile, experiences breakdown at similar cavitation numbers in both tests. As the breakdown of the pump occurs, the power required by that pump decreases, and the rotational speed of the turbopump increases. Compared with individual pump suction performance tests, this breakdown test can be used to determine the limit of the propellant inlet pressure of the turbopump and to characterize the behavior of the turbopump assembly when a breakdown occurs. Vibrations were also analyzed for tests at a high cavitation number and at the critical cavitation number. The vibration increased with breakdown and notable frequencies were analyzed.

Cavitation Experiments on Turbopump Inducers and Hydrofoils at Alta/Centrospazio: Overview and Future Activities

2005 ◽  
Author(s):  
Angelo Cervone ◽  
Cristina Bramanti ◽  
Emilio Rapposelli ◽  
Luca d’Agostino
Keyword(s):  
Thermal Effects ◽  
Cavity Length ◽  
Rocket Engine ◽  
Pressure Coefficient ◽  
Suction Side ◽  
Test Facility ◽  
Final Part ◽  
Cloud Cavitation ◽  
Naca 0015

The aim of the present paper is to provide some highlights about the most interesting experimental activities carried out during the years 2000–2004 through the CPRTF (Cavitating Pump Rotordynamic Test Facility) at Centrospazio/Alta S.p.A. After a brief description of the facility, the experimental activities carried out on a NACA 0015 hydrofoil for the characterization of the pressure coefficient on the suction side and evaluation the cavity length and oscillations are presented. Then, the results obtained to characterize the performance and the cavitation instabilities on three different axial inducers are showed: in particular, a commercial three-bladed inducer, the four-bladed inducer installed in the LOX turbopump of the Ariane Vulcain MK1 rocket engine and the “FAST2”, a two-bladed one manufactured by Avio S.p.A. using the criteria followed for the VINCI180 LOX inducer. The most interesting results are related to the effects of the temperature on the cavitation instabilities on hydrofoils and inducers. Experiments showed that some instabilities, like the cloud cavitation on hydrofoils and the surge on inducers, are strongly affected by the temperature, while others seem not to be influenced by the thermal effects. In the final part of this paper, some indications of the main experimental activities scheduled for the next future are provided.

scholarly journals Determination of receiver consumption characteristics using computer simulation

2020 ◽  
Vol 8 (2) ◽  
pp. 10-14
Author(s):  
S.S. Vasyliv ◽  
◽  
V.S. Zhdanov ◽  
M.V. Yevseyenko ◽  
◽  
...  
Keyword(s):  
Computer Simulation ◽  
Flow Rate ◽  
Rocket Engine ◽  
Flow Characteristics ◽  
Maximum Flow ◽  
Complex Configuration ◽  
Rocket Engines ◽  
Gas Leakage ◽  
Control Forces ◽  
Firing Tests

The problem of implementing the detonation mode of fuel combustion in thermal propulsion systems has been widely studied last decade. There are many works on fundamental and applied research on pulsating detonation. Solid propellant detonation engines can develop significant forces for a short time at low structural masses, and therefore they are ideal for auxiliary systems for the removal of separated rocket parts. In addition, detonation processes can be used to create control forces for correcting the trajectory of aircraft. All these facts determine the relevance of the area of work. For studying detonation installations, it is necessary to create test stands, but the design of test installations is an urgent and complex optimization problem. It is advisable to solve this problem with the help of computer simulation. In the existing experimental methods, for designing, it is necessary to determine in advance the geometric parameters of receivers and pipelines that provide the necessary gas consumption for firing tests of detonation rocket engines. The work is devoted to the development of a method for determining the flow characteristics of a receiver with a pipeline of complex configuration based on the constructed model of the stand. Based on the initial data, a computer simulation of the air leakage process from the receiver was carried out, for which the Solid Works software package was used. The places of pressure drop, maximum flow rate, and air mass flow are determined. The low value of the flow rate factor is due to the complex configuration of the pipeline with numerous bends and two bellows. Comparison of calculation results with experimental data was held. The difference between the experimental and calculated values does not exceed 3.6%. The obtained information is used to select the required value of the oxidizer excess coefficient during firing tests of detonation rocket engine models. Keywords: flow rate, gas leakage, receiver, model.

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