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Article
Publication date: 20 June 2019

Shiyu Feng, Chaoyue Li, Xiaotian Peng, Lei Shao and Weihua Liu

The purpose of this study is to measure the mass diffusion coefficient of nitrogen in jet fuel using digital holography interferometry for cost-effective designing and…

Abstract

Purpose

The purpose of this study is to measure the mass diffusion coefficient of nitrogen in jet fuel using digital holography interferometry for cost-effective designing and modeling of the aircraft tank inerting system.

Design/methodology/approach

The mass diffusion coefficients of N2 in RP-3 and RP-5 jet fuels were measured by digital holography interferometry at temperatures ranging from 278.15 to 343.15 K. The Arrhenius equation is used to adequately describe the relationship between mass diffusion coefficients and temperature. The viscosities of RP-3 and RP-5 jet fuels were also measured to examine the accuracy of the Stokes–Einstein model in calculating mass diffusion coefficients.

Findings

As temperature increases from 278.15 to 343.15 K, the mass diffusion coefficients increase 4.23-fold for N2 in RP-3 jet fuel and 5.13-fold for N2 in RP-5 jet fuel. The value of Dµ/T is not constant as the Stokes–Einstein equation expressed, but is a weak linear function of temperature.

Practical implications

A more accurate diffusion model is proposed by fitting the measured Dµ/T with the temperature and calculating the mass diffusion coefficients of N2 in RP-3 and RP-5 jet fuels within 10 per cent relative deviation.

Originality/value

A measurement system for mass diffusion coefficients of N2 in RP-3 and RP-5 jet fuels was constructed based on the digital holography interferometry. The mass diffusion coefficient can be expressed by a uniform polynomial function of temperature and viscosity.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 8
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 19 November 2018

Lei Shao, Shiyu Feng, Chaoyue Li, Weihua Liu and Xuying Huang

This paper aims to improve the previous fuel scrubbing model and find out the relationship between bubble diameter and scrubbing efficiency (ƞ).

Abstract

Purpose

This paper aims to improve the previous fuel scrubbing model and find out the relationship between bubble diameter and scrubbing efficiency (ƞ).

Design/methodology/approach

A fuel tank scrubbing test bench was established to verify the accuracy of this model. Ullage and dissolved oxygen concentration were measured, and images of bubble size and distribution were collected and analyzed using image analysis software.

Findings

The bubble diameter has a great influence on ullage and dissolved oxygen concentration during the fuel scrubbing process. The scrubbing efficiency (ƞ) has an exponential relationship with bubble diameter and decreases rapidly as the bubble diameter increases.

Practical implications

The variation of the ullage and dissolved oxygen concentration predicted by this model is more accurate than that of the previous model. In addition, the study of bubble size can provide a guidance for the design of fuel scrubber.

Originality/value

This study not only improves the previous fuel scrubbing model but also develops a method to calculate scrubbing efficiency (ƞ) based on bubble diameter. In addition, a series of tests and analyses were conducted, including numerical calculation, experiment and image analysis.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 2
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 8 January 2019

Chaoyue Li, Shiyu Feng, Lei Shao, Jun Pan and Weihua Liu

This study aims to get the essential data of the solubility and diffusion coefficient of gas in jet fuel for appropriately designing a kind of on-board inert gas generation system.

Abstract

Purpose

This study aims to get the essential data of the solubility and diffusion coefficient of gas in jet fuel for appropriately designing a kind of on-board inert gas generation system.

Design/methodology/approach

A test apparatus based on pressure–decay method was constructed to measure solubility and diffusion coefficient of gas in liquid. The test apparatus and method were verified via measurement of solubility and diffusion of CO2 in the pure water.

Findings

The solubility of CO2 and O2 in RP-3 jet fuel with the temperature from 253 to 313 K under three various pressures were measured and compared with theoretical value calculated by a relative density method provided in the standard of ASTM D2780-92, and the deviation is within 10 per cent. The diffusion coefficients of CO2 and O2 in RP-3 jet fuel are determined by monitoring the gas pressure in a hermetic cell versus time with the temperature from 253 to 333 K. The measured diffusivity-temperature relation can be well fitted through the Arrhenius equation for engineering applications. The obtained correlation can be used to predict the diffusion coefficient of CO2 and O2 in RP-3 jet fuel under a wide temperature range.

Practical implications

The semi-empirical correlation of solubility and diffusion coefficient in RP-3 jet fuel obtained from the experimental data could be used to support the design of an inert gas generation system.

Originality/value

There are no essential data of solubility and diffusion of CO2 and O2 in RP-3 jet fuel; therefore, it is fatal if the quantity and rate of mass transfer of CO2 and O2 in RP-3 jet fuel must be assessed, e.g. during the design of green on-board inert gas generation system.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 2
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 29 June 2020

Chaoyue Wang, Fujun Wang, Changliang Ye, Benhong Wang and Zhichao Zou

Tip leakage vortex flow (TLV) is a common flow phenomenon in the axial-flow hydraulic machinery. High-efficiency simulation of TLV is still not an easy task because of the…

Abstract

Purpose

Tip leakage vortex flow (TLV) is a common flow phenomenon in the axial-flow hydraulic machinery. High-efficiency simulation of TLV is still not an easy task because of the complex turbulent vortex-cavitation interactions. As an important basis of CFD, turbulence model directly affects the efficient computation of TLV. The purpose of this paper is to evaluate the newly developed MST turbulence model in predicting the TLV flows.

Design/methodology/approach

By using the MST turbulence model and the ZGB cavitation model, numerical simulations of the TLV generated by a NACA0009 hydrofoil were performed under the cavitation-free and cavitation conditions, and the results were compared with the available experimental data.

Findings

The important features of TLV are well captured by the MST-based simulation scheme, and the problem of under-predicting the cavitating TLV tube is well solved. Turbulent viscosity is reasonably adjusted in the TLV core regions, and the LES-like mode is activated, which is beneficial to obtain more turbulent information on the same URANS grids. The requirements of grid size and time step of the MST model are much lower than that of the LES method, thereby weighing a good balance between the simulation accuracy and computation cost.

Originality/value

The MST turbulence model is suitable for the high-efficiency simulation of the TLV flows, which can lay a good foundation for efficient engineering computations of the cavitating TLV in the axial-flow hydraulic machinery.

Details

Engineering Computations, vol. 38 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

Content available
Article
Publication date: 28 July 2020

Zhaozi Rong

This paper is a response to the doctrine that capital is incompatible with public ownership. The fundamental characteristics of modern productivity determine the…

Abstract

Purpose

This paper is a response to the doctrine that capital is incompatible with public ownership. The fundamental characteristics of modern productivity determine the co-existence of the market economy and capital relations.

Design/methodology/approach

Socialism can neither bypass the market economy nor “go beyond capital”; capital appears in two historical forms, including the private capital and the public capital. Public capital is the inevitable outcome of the inherent contradictions of public ownership in a socialist market economy.

Findings

It represents an economic relationship that compels individual labourers to provide surplus labour for the society. The combination of the strong accumulation function of public capital and the improvement of people's welfare is the main cause of China's development miracle.

Originality/value

The innovation impetus of the public capital and its “immunity” to the capitalist crisis highlight the tremendous power of socialism with Chinese characteristics in breaking free of the shackles of capitalism and continuously developing productive forces. Public capital demonstrates and will continue to demonstrate the historical legitimacy of socialism.

Details

China Political Economy, vol. 3 no. 1
Type: Research Article
ISSN: 2516-1652

Keywords

Content available
Article
Publication date: 1 February 2018

Xuhui Ye, Gongping Wu, Fei Fan, XiangYang Peng and Ke Wang

An accurate detection of overhead ground wire under open surroundings with varying illumination is the premise of reliable line grasping with the off-line arm when the…

Abstract

Purpose

An accurate detection of overhead ground wire under open surroundings with varying illumination is the premise of reliable line grasping with the off-line arm when the inspection robot cross obstacle automatically. This paper aims to propose an improved approach which is called adaptive homomorphic filter and supervised learning (AHSL) for overhead ground wire detection.

Design/methodology/approach

First, to decrease the influence of the varying illumination caused by the open work environment of the inspection robot, the adaptive homomorphic filter is introduced to compensation the changing illumination. Second, to represent ground wire more effectively and to extract more powerful and discriminative information for building a binary classifier, the global and local features fusion method followed by supervised learning method support vector machine is proposed.

Findings

Experiment results on two self-built testing data sets A and B which contain relative older ground wires and relative newer ground wire and on the field ground wires show that the use of the adaptive homomorphic filter and global and local feature fusion method can improve the detection accuracy of the ground wire effectively. The result of the proposed method lays a solid foundation for inspection robot grasping the ground wire by visual servo.

Originality/value

This method AHSL has achieved 80.8 per cent detection accuracy on data set A which contains relative older ground wires and 85.3 per cent detection accuracy on data set B which contains relative newer ground wires, and the field experiment shows that the robot can detect the ground wire accurately. The performance achieved by proposed method is the state of the art under open environment with varying illumination.

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