scholarly journals The World’s First Test Facility That Enables the Experimental Visualization of Cavitation on a Rotating Inducer in Both Cryogenic and Ordinary Fluids

2021 ◽  
Author(s):  
Yu Ito
Keyword(s):  
Flow Visualization ◽  
Liquid Nitrogen ◽  
Cavitation Number ◽  
Tip Vortex ◽  
Test Facility ◽  
Working Fluid ◽  
Cryogenic Pump ◽  
Thermodynamic Effect ◽  
Pump Head ◽  
Visualization Experiments

Abstract It is well known that cavitation breakdown, which is a phenomenon in which the pump head suddenly drops with a decrease in the inlet cavitation number, occurs in turbopumps. Especially in cryogenic pumps, cavitation breakdown occurs at a lower inlet cavitation number than that of ordinary fluids such as water. This phenomenon is referred to as a thermodynamic effect, as Stepanoff reported. The thermodynamic properties of the working fluid affect the sizes of cavitation elements, and the sizes affect cavitation breakdown; therefore, experimental flow visualization is an effective approach to realize a more efficient and more reliable cryogenic pump. In 2010, the author and colleagues developed the worldߣs first test facility to enable the visualization of cavitation on a rotating inducer in both cryogenic and ordinary fluids. At that time, only two reports on the flow visualization of a rotating cryogenic impeller had been published: one on flow visualization in liquid hydrogen by NASA in 1967 and the other in liquid nitrogen by JAXA in 2010. The present facility employs a triple-thread helical inducer with a diameter of 65.3 mm and a rotation rate of up to 8000 rpm with both liquid nitrogen and water available as working fluids. Unsteady visualization experiments for cavitation on an inducer in liquid nitrogen and water have revealed the characteristics of tip vortex cavitation, backflow vortex cavitation, and cavitation element size based on comparisons between cryogenic fluids that exhibit a stronger thermodynamic effect and ordinary fluids such as water.

scholarly journals Influence of Thermodynamic Effect on Blade Load in a Cavitating Inducer

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Kengo Kikuta ◽  
Noriyuki Shimiya ◽  
Tomoyuki Hashimoto ◽  
Mitsuru Shimagaki ◽  
Hideaki Nanri ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Liquid Nitrogen ◽  
Cavity Length ◽  
Cold Water ◽  
Pressure Rise ◽  
Cavitation Number ◽  
Design Parameters ◽  
Trailing Edge ◽  
Thermodynamic Effect ◽  
Blade Tip

Distribution of the blade load is one of the design parameters for a cavitating inducer. For experimental investigation of the thermodynamic effect on the blade load, we conducted experiments in both cold water and liquid nitrogen. The thermodynamic effect on cavitation notably appears in this cryogenic fluid although it can be disregarded in cold water. In these experiments, the pressure rise along the blade tip was measured. In water, the pressure increased almost linearly from the leading edge to the trailing edge at higher cavitation number. After that, with a decrease of cavitation number, pressure rise occurred only near the trailing edge. On the other hand, in liquid nitrogen, the pressure distribution was similar to that in water at a higher cavitation number, even if the cavitation number as a cavitation parameter decreased. Because the cavitation growth is suppressed by the thermodynamic effect, the distribution of the blade load does not change even at lower cavitation number. By contrast, the pressure distribution in liquid nitrogen has the same tendency as that in water if the cavity length at the blade tip is taken as a cavitation indication. From these results, it was found that the shift of the blade load to the trailing edge depended on the increase of cavity length, and that the distribution of blade load was indicated only by the cavity length independent of the thermodynamic effect.

Flow Visualization and Leakage Measurements of Stepped Labyrinth Seals: Part 1—Annular Groove

1997 ◽  
Vol 119 (4) ◽  
pp. 839-843 ◽  
Author(s):  
D. L. Rhode ◽  
J. W. Johnson ◽  
D. H. Broussard
Keyword(s):  
Flow Visualization ◽  
Large Scale ◽  
Digital Images ◽  
Test Facility ◽  
Labyrinth Seals ◽  
Water Leakage ◽  
Tracer Particles ◽  
Leakage Resistance ◽  
Visualization Experiments ◽  
Resistance Improvement

An improved understanding of a new category of stepped labyrinth seals, which feature a new “annular groove,” was obtained. A water leakage and flow visualization test facility of very large scale (relative to a typical seal) was utilized. Flow visualization experiments using a new method and digital facilities for capturing and editing digital images from an 8 mm video were conducted. The presence of an annular groove machined into the stator land increases the leakage resistance by up to 26 percent for the cases considered here. Tracer particles show the degree of throughflow path penetration into the annular groove (i.e., serpentining), which gives the largest and the smallest leakage resistance improvement over that of the corresponding conventional stepped seal.

Experiments on Delta Wings in Superventilated Flow

1967 ◽  
Vol 11 (01) ◽  
pp. 9-19
Author(s):  
T. Kiceniuk
Keyword(s):  
Flow Visualization ◽  
Angle Of Attack ◽  
Cavitation Number ◽  
Water Tunnel ◽  
Force Measurements ◽  
Delta Wings ◽  
Visualization Experiments

An extensive water-tunnel investigation of super ventilated delta wings has been concluded. Force measurements and flow-visualization experiments were carried out for wings of several apex angles and various values of cavitation number, submergence, velocity, and angle of attack. Some unusual model geometries and orientations were also explored.

Investigation of the cavitation model in an inducer for water and liquid nitrogen

2019 ◽  
Vol 233 (19-20) ◽  
pp. 6939-6952
Author(s):  
Yuqiao Zhang ◽  
Xiaodong Ren ◽  
Yan Wang ◽  
Xuesong Li ◽  
Yu Ito ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Liquid Nitrogen ◽  
Cavitation Number ◽  
Tip Vortex ◽  
Dynamics Simulation ◽  
Computational Fluid Dynamics Simulation ◽  
Cavitation Model ◽  
Model Features ◽  
Empirical Constants

Cavitation commonly occurs in the hydraulic machineries like inducers. Cavitation happening in the cryogens is sophisticated due to their complicated thermodynamic properties. Computational fluid dynamics could provide relatively precise prediction for water. However, existing computational fluid dynamics methods may fail to simulate the cryogens cavitation precisely. This study presents a computational fluid dynamics simulation of four major cavitation models in both the liquid nitrogen and the water in an inducer. Four different cavitation models analyzed in this work are full cavitation model, Kunz model, Zwart–Gerber–Belamri, and Schnerr & Sauer. And the computational fluid dynamics simulation results are verified by the experiment to ensure the cavitation model's applicability in both liquid. Comparison of cavitation in water and liquid nitrogen is conducted and analyzed. The four cavitation models can predict cavitation in water, but the Zwart–Gerber–Belamri model and Schnerr & Sauer model also feature high capability to predict tip vortex cavitation. The results show that the full cavitation model is suitable for simulating the liquid nitrogen cavitation without changing of the model constants. The empirical constants of the other models should be adjusted in the liquid nitrogen cavitation simulation. Full cavitation model features high robustness in various liquids. The Schnerr & Sauer model can achieve the best results by adopting different empirical constants. In addition, the inducer performs better in the liquid nitrogen than water at low cavitation number regime as the head coefficient drops smoothly in liquid nitrogen with decreasing cavitation number.

Thermodynamic Effect on a Cavitating Inducer in Liquid Nitrogen

2006 ◽  
Vol 129 (3) ◽  
pp. 273-278 ◽  
Author(s):  
Yoshiki Yoshida ◽  
Kengo Kikuta ◽  
Satoshi Hasegawa ◽  
Mitsuru Shimagaki ◽  
Takashi Tokumasu
Keyword(s):  
Liquid Nitrogen ◽  
Cavity Length ◽  
Cold Water ◽  
Cavitation Number ◽  
Experimental Investigations ◽  
Thermodynamic Effect ◽  
Blade Tip ◽  
Cryogenic Flow ◽  
The Difference ◽  
Temperature Depression

For experimental investigations of the thermodynamic effect on a cavitating inducer, it is nesessary to observe the cavitation. However, visualizations of the cavitation are not so easy in cryogenic flow. For this reason, we estimated the cavity region in liquid nitrogen based on measurements of the pressure fluctuation near the blade tip. In the present study, we focused on the length of the tip cavitation as a cavitation indicator. Comparison of the tip cavity length in liquid nitrogen (80K) with that in cold water (296K) allowed us to estimate the strength of the thermodynamic effect. The degree of thermodynamic effect was found to increase with an increase of the cavity length. The temperature depression was estimated from the difference of the cavitation number of corresponding cavity condition (i.e., cavity length) between in liquid nitrogen and in cold water. The estimated temperature depression caused by vaporization increased rapidly when the cavity length extended over the throat. In addition, the estimated temperature inside the bubble nearly reached the temperature of the triple point when the pump performance deteriorated.

Flow Visualization and Leakage Measurements of Stepped Labyrinth Seals: Part 1 — Annular Groove

1996 ◽  
Author(s):  
David L. Rhode ◽  
James W. Johnson ◽  
Daniel H. Broussard
Keyword(s):  
Flow Visualization ◽  
Large Scale ◽  
Digital Images ◽  
Test Facility ◽  
Labyrinth Seals ◽  
Water Leakage ◽  
Tracer Particles ◽  
Leakage Resistance ◽  
Visualization Experiments ◽  
Resistance Improvement

An improved understanding of a new category of stepped labyrinth seals, which feature a new “annular groove”, was obtained. A water leakage and flow visualization test facility of very large scale (relative to a typical seal) was utilized. Flow visualization experiments using a new method and digital facilities for capturing and editing digital images from an 8 mm video were conducted. The presence of an annular groove machined into the stator land increases the leakage resistance by up to 26 percent for the cases considered here. Tracer particles show the degree of throughflow path penetration into the annular groove (i.e. serpentining), which gives the largest and the smallest leakage resistance improvement over that of the corresponding conventional stepped seal.

Thermodynamic Effect on Cavitation Performances and Cavitation Instabilities in an Inducer

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
Kengo Kikuta ◽  
Yoshiki Yoshida ◽  
Mitsuo Watanabe ◽  
Tomoyuki Hashimoto ◽  
Katsuji Nagaura ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Temperature Difference ◽  
Cavity Length ◽  
Cold Water ◽  
Experimental Results ◽  
Working Fluid ◽  
Blade Passage ◽  
Thermodynamic Effect

Based on the length of the tip cavitation as an indication of cavitation, we focused on the effect of thermodynamics on cavitation performances and cavitation instabilities in an inducer. Comparison of the tip cavity length in liquid nitrogen (76K and 80K) as working fluid with that in cold water (296K) allowed us to estimate the strength of the thermodynamic effect on the cavitations. The degree of thermodynamic effect was found to increase with an increase of the cavity length, particularly when the cavity length extended over the throat of the blade passage. In addition, cavitation instabilities occurred both in liquid nitrogen and in cold water when the cavity length increased. Subsynchronous rotating cavitation appeared both in liquid nitrogen and in cold water. In the experiment using liquid nitrogen, the temperature difference between 76K and 80K affected the range in which the subsynchronous rotating cavitation occurred. In contrast, deep cavitation surge appeared only in cold water at lower cavitation numbers. From these experimental results, it was concluded that when the cavity length extends over the throat, the thermodynamic effect also affects the cavitation instabilities as a “thermal damping” through the unsteady cavitation characteristics.

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.

Modification of Energy Equation for Homogeneous Cavitation Simulation With Thermodynamic Effect

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Anh Dinh Le ◽  
Junosuke Okajima ◽  
Yuka Iga
Keyword(s):  
Thermodynamic Model ◽  
Saturated Vapor ◽  
Homogeneous Model ◽  
Industrial Applications ◽  
Working Fluid ◽  
Suppression Effect ◽  
Evaporation And Condensation ◽  
Thermodynamic Effect ◽  
Cavitation Region ◽  
Cryogenic Liquids

In industrial applications, cryogenic liquids are sometimes used as the working fluid of fluid machineries. In those fluids, the thermodynamic suppression effect of cavitation, which is normally ignored in water at room temperature, becomes obvious. When evaporation occurs in the cavitation region, the heat is supplied from the surrounding liquid. Hence, the liquid temperature is decreased, and cavitation is suppressed due to the decrease in saturated vapor pressure. Therefore, the performance of the fluid machinery can be improved. Computational fluid dynamics, which involves the use of a homogeneous model coupled with a thermal transport equation, is a powerful tool for the prediction of cavitation under thermodynamic effects. In this study, a thermodynamic model for a homogeneous model is introduced. In this model, the source term related to the latent heat of phase change appears explicitly, and the degree of heat transfer rate for evaporation and condensation can be adjusted separately to suit the homogeneous model. Our simplified thermodynamic model coupled with the Merkle cavitation model was validated for cryogenic cavitation on a two-dimensional (2D) quarter hydrofoil. The results obtained during the validation showed good agreement (in both pressure and temperature profiles) with the experimental data and were better than existing numerical results obtained by other researchers.

Performance Results With ALSTOM’s Circulating Moving Bed Combuster™

2003 ◽  
Author(s):  
Glen Jukkola ◽  
Armand Levasseur ◽  
Dave Turek ◽  
Bard Teigen ◽  
Suresh Jain ◽  
...  
Keyword(s):  
High Temperature ◽  
Test Facility ◽  
Working Fluid ◽  
Massachusetts Institute Of Technology ◽  
Combustion System ◽  
Moving Bed ◽  
Program Cost ◽  
Capital Costs ◽  
Institute Of Technology ◽  
Performance Results

ALSTOM is developing and testing a new and more efficient coal combustion technology, including a new type of steam generator known as a “circulating moving bed (CMBTM) combustion system combustor.” The CMBTM combustion system technology involves a novel method of solid fuel combustion and heat transfer. In this design, a heat exchanger will heat the energy cycle working fluid, steam or air, to the high temperature levels required for advanced power generation systems. This will produce a step change in both performance and capital costs relative to today’s pulverized coal and fluid bed boiler designs. In addition to high temperature Rankine cycles, the CMBTM combustion system is an enabling technology for hydrogen production and CO2 capture from combustion systems utilizing innovative chemical looping airblown gasification and syngas decarbonization. ALSTOM’s 3MWth Multi-Use Combustion Test Facility has been modified to allow operation in CMBTM combustion system mode. This paper summarizes the results of this program, which includes performance results from pilot plant testing. Participants include the U.S. DOE, ALSTOM, the University of Massachusetts, and the Massachusetts Institute of Technology. The total program cost is $2,485,468 with the DOE’s National Energy Technology Laboratory (NETL) providing 60% of the funding under Cooperative Agreement No. DE-FC26-01NT41223.

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