Inducer Design Optimization to Improve its Suction Performance

2019 ◽  
Author(s):  
Yushi Nakamura ◽  
Marek Lubieniecki ◽  
Kentarou Hayashi ◽  
Yutaka Kawata ◽  
Masahiro Miyabe ◽  
...  
Keyword(s):  
Response Surface ◽  
Design Space ◽  
Cavitation Number ◽  
Design Parameters ◽  
Baseline Design ◽  
Starting Point ◽  
Blade Shape ◽  
Critical Cavitation ◽  
Suction Performance ◽  
The Relationship

Abstract The purpose of this paper is to present optimization method of an inducer blade shape to improve its suction performance and clarify the relationship between pump performance and design parameters. In order to conduct the optimization process a response surface based optimization framework was established. Baseline was designed in previous research [1]. The inducers were 3Dprinted in ABS plastic and their wetted and cavitating characteristics were measured. It was confirmed that the optimized inducer can maintain its wetted performance at lower cavitation numbers. A response surface is a mathematical model that approximates the relationship between the input parameters and the objective function from a finite number of learning points within the design space. The design space was defined by four parameters: sweep angle, sweep radius, incidence angle and blade solidity at the tip that controlled the blade shape. The performance of each design was evaluated with a CFD simulation established in a commercial solver. The optimization goal was to minimize the critical cavitation number that corresponds to a 5% drop of pressure increase through the pump due to cavitation. A starting point of the optimization was the industrial pump designed by a Japanese company Teral [1]. The results of the numerical optimization show that the critical cavitation number was decreased by 17.6% with respect to the baseline design. In the experimental results, an average improvement of 15.4% was achieved.

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.

Thermodynamic Effect on Rotating Cavitation in an Inducer

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Yoshiki Yoshida ◽  
Yoshifumi Sasao ◽  
Mitsuo Watanabe ◽  
Tomoyuki Hashimoto ◽  
Yuka Iga ◽  
...  
Keyword(s):  
Cavity Length ◽  
Cavity Growth ◽  
Cavitation Number ◽  
Liquid Temperature ◽  
Cryogenic Fluids ◽  
Thermodynamic Effect ◽  
Different Temperatures ◽  
Critical Cavitation ◽  
Thermal Imbalance ◽  
The Relationship

Cavitation in cryogenic fluids has a thermodynamic effect because of the thermal imbalance around the cavity. It improves cavitation performances in turbomachines due to the delay of cavity growth. The relationship between the thermodynamic effect and cavitation instabilities, however, is still unknown. To investigate the influence of the thermodynamic effect on rotating cavitation appeared in the turbopump inducer, we conducted experiments in which liquid nitrogen was set at different temperatures (74 K, 78 K, and 83 K) with a focus on the cavity length. At higher cavitation numbers, supersynchronous rotating cavitation occurred at the critical cavity length of Lc/h≅0.5 with a weak thermodynamic effect in terms of the fluctuation of cavity length. In contrast, synchronous rotating cavitation occurred at the critical cavity length of Lc/h≅0.9–1.0 at lower cavitation numbers. The critical cavitation number shifted to a lower level due to the suppression of cavity growth by the thermodynamic effect, which appeared significantly with rising liquid temperature. The unevenness of cavity length under synchronous rotating cavitation was decreased by the thermodynamic effect. Furthermore, we confirmed that the fluid force acting on the inducer notably increased under conditions of rotating cavitation, but that the amplitude of the shaft vibration depended on the degree of the unevenness of the cavity length through the thermodynamic effect.

Investigation on the Pump Suction Performance and Thermodynamic Effects

2020 ◽  
Author(s):  
Eunhwan Jeong ◽  
Byung Yun Kang ◽  
Soon Sam Hong ◽  
Dae Jin Kim ◽  
Chang Ho Choi
Keyword(s):  
Performance Test ◽  
Rocket Engine ◽  
Cavitation Number ◽  
Liquid Oxygen ◽  
Inlet Temperature ◽  
Test Results ◽  
Pump Head ◽  
Thermodynamic Effects ◽  
Critical Cavitation ◽  
Suction Performance

Abstract The thermodynamic effects on the suction performance of a liquid oxygen (LOX) pump, observed during liquid rocket engine combustion tests, were investigated. Owing to the pump rotational speed and inlet pressure variation in the short duration of the engine starting, LOX pump head drops occurred occasionally depending on the initial pump inlet condition. Because the engine tests were performed at various inlet temperature and pressure settings of the LOX pump, the resulting suction performance behaviors of the LOX pump were varied. The critical cavitation number, at which the pump head drops 3%, was considered as the main parameter for representing the pump suction performance. The suction performance behaviors shown in the engine tests were investigated based on the classical theory of thermodynamic effects on cavitation. The LOX pump component test results in water, the LOX pump assembly suction performance test results in liquid nitrogen, and the J-2 LOX pump test results available in the open literature were used in the analysis and comparison. It was found that the critical cavitation number ratio of a pump could be expressed as a function of the thermodynamic parameter Σ*. For a given LOX pump flow condition, Stepanoff’s B-factor was almost constant at the specified head drop condition; as a result, Brennen’s time scale ratio βwas not constant but varying with Σ*. The argument of the geometrical similarity of pump cavitation at the critical condition of the pump head drop was addressed in conjunction with the constancy of Stepanoff B-factor.

Optimal kinematic design of a three translational DoFs parallel manipulator

Robotica ◽  
2005 ◽  
Vol 24 (2) ◽  
pp. 239-250 ◽  
Author(s):  
Xin-Jun Liu
Keyword(s):  
Parallel Manipulator ◽  
Design Space ◽  
Design Method ◽  
Performance Criteria ◽  
Stiffness Index ◽  
Design Parameters ◽  
Kinematic Design ◽  
Normalized Parameters ◽  
The Relationship ◽  
Design Result

In this paper, an optimal kinematic design method of a three translational DoFs parallel manipulator is presented. The design is based on the concept of performance chart, which can show the relationship between a criterion and design parameters graphically and globally. The normalization on the design parameters of the studied manipulator makes it possible that the design space, which is made up of the normalized parameters, is limited. The design space includes of all possible basic similarity manipulators (BSMs). As any one of the BSMs represents all of its similarity manipulators (SMs) in terms of performances, if one BSM is optimal, its SMs are optimized as well. The said optimal BSM is from the optimum region, which is the intersecting result of involved performance charts. In this paper, the related performance criteria are good-conditioning workspace (GCW), global conditioning index (GCI) and global stiffness index (GSI). As an applying example, a design result of the parallel manipulator with a desired task workspace is presented. The results of the paper are very useful for the design and application of a parallel manipulator.

Multi-Response Surface Optimisation with Different Priorities for Ramp Process Parameter Design

2012 ◽  
Vol 548 ◽  
pp. 744-748 ◽  
Author(s):  
Rewadee Inkaew ◽  
Pongchanun Luangpaiboon
Keyword(s):  
Response Surface ◽  
Descent Method ◽  
Process Parameter ◽  
Steepest Descent Method ◽  
Parameter Design ◽  
Design Parameters ◽  
Noisy Environment ◽  
Actual Performance ◽  
Proposed Model ◽  
The Relationship

This study proposes a multi-response surface optimisation with different priorities (MRSOP) problem for determining the proper choices of a process parameter design (PPD) decision problem in a noisy environment of a ramp process in plastic injection molding. The proposed model attempts to minimise process responses of the flow mark defect and mold deposit. Firstly, Taguchi design and analysis are applied to screen out controllable design parameters significantly affecting the quality performances and the regression is then used to determine the form of the relationship between the response and design parameters. A numerical example demonstrates the feasibility of applying the proposed model to the PPD problem via two iterative methods. Its advantages are also discussed. Numerical results demonstrate that the steepest descent method is superior to the use of the linear constrained response surface optimisation method. In this study, the flow mark defect reduces from 2.63 to 1.45% and mold deposit measured by the mold cleaning frequency decreases from every 2.57 to 1.86 hours on average. All experimental data presented in this research have been normalised to disguise actual performance measures as raw data are considered to be confidential.

DIAGNOSING QUALITY OF FRICTION SYSTEMS OF MECHANISMS OF DEVICES

2019 ◽  
Vol 1 (7) ◽  
pp. 10-13
Author(s):  
D. Yu. Ershov ◽  
I. N. Lukyanenko ◽  
E. E. Aman
Keyword(s):  
Surface Defects ◽  
Diagnostic Methods ◽  
Design Parameters ◽  
Diagnostic Model ◽  
Mechanical Assemblies ◽  
Local Defects ◽  
Relationship Of ◽  
The Relationship ◽  
Production And Operation

The article shows the need to develop diagnostic methods for monitoring the quality of lubrication systems, which makes it possible to study the dynamic processes of contacting elements of the friction systems of instrument mechanisms, taking into account roughness parameters, the presence of local surface defects of elements and the bearing capacity of a lubricant. In the present article, a modern diagnostic model has been developed to control the quality of the processes of production and operation of friction systems of instrument assemblies. With the help of the developed model, it becomes possible to establish the relationship of diagnostic and design parameters of the mechanical system, as well as the appearance of possible local defects and lubricant state, which characterize the quality of friction systems used in many mechanical assemblies of the mechanisms of devices. The research results are shown in the form of nomograms to assess the defects of the elements of friction mechanisms of the mechanisms of the devices.

CYBERCHONDRIA INFORMATION CLINIC: Internet's Impact on your Health (Preprint)

2019 ◽  
Author(s):  
Valentina Escotet Espinoza
Keyword(s):  
Human Life ◽  
Brain Regions ◽  
Physical Symptoms ◽  
Digital Design ◽  
Somatization Disorder ◽  
The Internet ◽  
Cultural Aspects ◽  
Starting Point ◽  
The Right ◽  
The Relationship

UNSTRUCTURED Over half of Americans report looking up health-related questions on the internet, including questions regarding their own ailments. The internet, in its vastness of information, provides a platform for patients to understand how to seek help and understand their condition. In most cases, this search for knowledge serves as a starting point to gather evidence that leads to a doctor’s appointment. However, in some cases, the person looking for information ends up tangled in an information web that perpetuates anxiety and further searches, without leading to a doctor’s appointment. The Internet can provide helpful and useful information; however, it can also be a tool for self-misdiagnosis. Said person craves the instant gratification the Internet provides when ‘googling’ – something one does not receive when having to wait for a doctor’s appointment or test results. Nevertheless, the Internet gives that instant response we demand in those moments of desperation. Cyberchondria, a term that has entered the medical lexicon in the 21st century after the advent of the internet, refers to the unfounded escalation of people’s concerns about their symptomatology based on search results and literature online. ‘Cyberchondriacs’ experience mistrust of medical experts, compulsion, reassurance seeking, and excessiveness. Their excessive online research about health can also be associated with unnecessary medical expenses, which primarily arise from anxiety, increased psychological distress, and worry. This vicious cycle of searching information and trying to explain current ailments derives into a quest for associating symptoms to diseases and further experiencing the other symptoms of said disease. This psychiatric disorder, known as somatization, was first introduced to the DSM-III in the 1980s. Somatization is a psycho-biological disorder where physical symptoms occur without any palpable organic cause. It is a disorder that has been renamed, discounted, and misdiagnosed from the beginning of the DSMs. Somatization triggers span many mental, emotional, and cultural aspects of human life. Our environment and social experiences can lay the blueprint for disorders to develop over time; an idea that is widely accepted for underlying psychiatric disorders such as depression and anxiety. The research is going in the right direction by exploring brain regions but needs to be expanded on from a sociocultural perspective. In this work, we explore the relationship between somatization disorder and the condition known as cyberchondria. First, we provide a background on each of the disorders, including their history and psychological perspective. Second, we proceed to explain the relationship between the two disorders, followed by a discussion on how this relationship has been studied in the scientific literature. Thirdly, we explain the problem that the relationship between these two disorders creates in society. Lastly, we propose a set of intervention aids and helpful resource prototypes that aim at resolving the problem. The proposed solutions ranged from a site-specific clinic teaching about cyberchondria to a digital design-coded chrome extension available to the public.

On Shaky Ground? Exploring the Contingent Fundamentality Thesis

2018 ◽  
Author(s):  
Nathan Wildman
Keyword(s):  
Possible World ◽  
Starting Point ◽  
The Relationship ◽  
Shaky Ground

The relationship between fundamentality and modality remains criminally underexplored. In particular, there are several significant questions about fundamentality’s modal strength that remain unanswered. For example, if something is fundamental is it necessarily so? That is, could something be fundamental in one possible world and derivative in another? And how would the acceptance of contingent fundamentality square with commitments to contingentism (or, for that matter, necessitism) about the existence of the fundamentalia? Chapter 14 makes some headway towards addressing these questions. It does so by exploring the contingent fundamentality thesis, according to which it is possible that something is possibly fundamental and possibly derivative. In this way, the chapter represents a starting point for examining broader issues about the relationship between fundamentality and modality.

scholarly journals Influence of Selected Model Parameters on the Electromagnetic Levitation Melting Efficiency

2021 ◽  
Vol 11 (9) ◽  
pp. 3827
Author(s):  
Blazej Nycz ◽  
Lukasz Malinski ◽  
Roman Przylucki
Keyword(s):  
Electromagnetic Levitation ◽  
Optimization Methods ◽  
Calculation Model ◽  
Model Parameters ◽  
Starting Point ◽  
Low Efficiency ◽  
The Relationship ◽  
Reactive Metals ◽  
Electromagnetic Levitation Melting ◽  
Metal Melting

The article presents the results of multivariate calculations for the levitation metal melting system. The research had two main goals. The first goal of the multivariate calculations was to find the relationship between the basic electrical and geometric parameters of the selected calculation model and the maximum electromagnetic buoyancy force and the maximum power dissipated in the charge. The second goal was to find quasi-optimal conditions for levitation. The choice of the model with the highest melting efficiency is very important because electromagnetic levitation is essentially a low-efficiency process. Despite the low efficiency of this method, it is worth dealing with it because is one of the few methods that allow melting and obtaining alloys of refractory reactive metals. The research was limited to the analysis of the electromagnetic field modeled three-dimensionally. From among of 245 variants considered in the article, the most promising one was selected characterized by the highest efficiency. This variant will be a starting point for further work with the use of optimization methods.

scholarly journals Evaluation of Static Mapping for Dynamic Space-Shared Multi-task Processing on FPGAs

2021 ◽  
Author(s):  
Umar Ibrahim Minhas ◽  
Roger Woods ◽  
Georgios Karakonstantis
Keyword(s):  
High Performance ◽  
Design Space Exploration ◽  
Design Space ◽  
System Throughput ◽  
Design Parameters ◽  
Temporal Constraints ◽  
Shared Resources ◽  
Task Processing ◽  
High Level ◽  
Performance Computing

AbstractWhilst FPGAs have been used in cloud ecosystems, it is still extremely challenging to achieve high compute density when mapping heterogeneous multi-tasks on shared resources at runtime. This work addresses this by treating the FPGA resource as a service and employing multi-task processing at the high level, design space exploration and static off-line partitioning in order to allow more efficient mapping of heterogeneous tasks onto the FPGA. In addition, a new, comprehensive runtime functional simulator is used to evaluate the effect of various spatial and temporal constraints on both the existing and new approaches when varying system design parameters. A comprehensive suite of real high performance computing tasks was implemented on a Nallatech 385 FPGA card and show that our approach can provide on average 2.9 × and 2.3 × higher system throughput for compute and mixed intensity tasks, while 0.2 × lower for memory intensive tasks due to external memory access latency and bandwidth limitations. The work has been extended by introducing a novel scheduling scheme to enhance temporal utilization of resources when using the proposed approach. Additional results for large queues of mixed intensity tasks (compute and memory) show that the proposed partitioning and scheduling approach can provide higher than 3 × system speedup over previous schemes.

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