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Article
Publication date: 3 May 2016

Bengt Ake Sunden, Zan Wu and Dan Huang

The purpose of this paper is to numerically investigate the heat transfer performance of aviation kerosene flowing in smooth and enhanced tubes with asymmetric fins at…

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Abstract

Purpose

The purpose of this paper is to numerically investigate the heat transfer performance of aviation kerosene flowing in smooth and enhanced tubes with asymmetric fins at supercritical pressures and to reveal the effects of several key parameters, such as mass flow rate, heat flux, pressure and inlet temperature on the heat transfer.

Design/methodology/approach

A CFD approach is taken and the strong variations of the thermo-physical properties as the critical point is passed are taken into account. The RNG k-ε model is applied for simulating turbulent flow conditions.

Findings

The numerical results reveal that the heat transfer coefficient increases with increasing mass flow rate and inlet temperature. The effect of heat flux on heat transfer is more complicated, while the effect of pressure on heat transfer is insignificant. The considered asymmetric fins have a small effect on the fluid temperature, but the wall temperature is reduced significantly by the asymmetric fins compared to that of the corresponding smooth tube. As a result, the asymmetric finned tube leads to a significant heat transfer enhancement (an increase in the heat transfer coefficient about 23-41 percent). The enhancement might be caused by the re-development of velocity and temperature boundary layers in the enhanced tubes. With the asymmetric fins, the pressure loss in the enhanced tubes is slightly larger than that in the smooth tube. A thermal performance factor is applied for combined evaluation of heat transfer enhancement and pressure loss.

Research limitations/implications

The asymmetric fins also caused an increased pressure loss. A thermal performance factor ? was used for combined evaluation of heat transfer enhancement and pressure loss. Results show that the two enhanced tubes perform better than the smooth tube. The enhanced tube 2 gave better overall heat transfer performance than the enhanced tube 1. It is suggested that the geometric parameters of the asymmetric fins should be optimized to further improve the thermal performance and also various structures need to be investigated.

Practical implications

The asymmetric fins increased the pressure loss. The evaluation of heat transfer enhancement and pressure loss Results showed that the two enhanced tubes perform better than the smooth tube. It is suggested that the geometric parameters of the asymmetric fins should be optimized to further improve the thermal performance and also various structures need to be investigated to make the results more engineering useful.

Originality/value

The paper presents unique solutions for thermal performance of a fluid at near critical state in smooth and enhanced tubes. The findings are of relevance for design and thermal optimization particularly in aerospace applications.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 3/4
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 17 August 2015

Yong Cao, Shusheng Bi, Yueri Cai and Yuliang Wang

– This paper aims to develop a robofish with oscillating pectoral fins, and control it to mimic the bionic prototype by central pattern generators (CPGs).

Abstract

Purpose

This paper aims to develop a robofish with oscillating pectoral fins, and control it to mimic the bionic prototype by central pattern generators (CPGs).

Design/methodology/approach

First, the oscillation characteristics of the cownose ray were analyzed quantitatively. Second, a robofish with multi-joint pectoral fins was developed according to the bionic morphology and kinematics. Third, the improved phase oscillator was established, which contains a spatial asymmetric coefficient and a temporal asymmetric coefficient. Moreover, the CPG network is created to mimic the cownose ray and accomplish three-dimensional (3D) motions. Finally, the experiments were done to test the authors ' works.

Findings

The results demonstrate that the CPGs is effective to control the robofish to imitate the cownose ray realistically. In addition, the robofish is able to accomplish 3D motions of high maneuverability, and change among different swimming modes quickly and smoothly.

Originality/value

The research provides the method to develop a robofish from both 3D morphology and kinematics. The motion analysis and CPG control make sure that the robofish has the features of high maneuverability and camouflage. It is useful for military underwater applications and underwater detections in narrow environments. Second, this work lays the foundation for the autonomous 3D control. Moreover, the robotic fish can be taken as a scientific tool for the fluid bionics research.

Details

Industrial Robot: An International Journal, vol. 42 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 1 September 1947

F/O P.L. Bisgood

THE lift coefficient of an aerofoil fitted with a hinged control flap and a tab can be expressed in the form:

Abstract

THE lift coefficient of an aerofoil fitted with a hinged control flap and a tab can be expressed in the form:

Details

Aircraft Engineering and Aerospace Technology, vol. 19 no. 9
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 January 1970

Five integral fuel tanks are carried in the fuselage. Port and starboard side tanks of 51½ gallons (234 litres) capacity each between the front engine nozzles and the engine air…

Abstract

Five integral fuel tanks are carried in the fuselage. Port and starboard side tanks of 51½ gallons (234 litres) capacity each between the front engine nozzles and the engine air intakes, a further pair of side tanks of 39 gallons (178 litres) capacity each between the front and rear engine nozzles, and a central tank of 104 gallons (473 litres) capacity occupying the upper portion of the fuselage immediately aft of the wing.

Details

Aircraft Engineering and Aerospace Technology, vol. 42 no. 1
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 2 August 2019

Yong Cao, Yang Lu, Yueri Cai, Shusheng Bi and Guang Pan

This paper aims to imitate a cownose ray to develop a fish robot with paired flexible multi-fin-ray oscillating pectoral fins (OPFs) and control it to accomplish vivid stable 3-D…

Abstract

Purpose

This paper aims to imitate a cownose ray to develop a fish robot with paired flexible multi-fin-ray oscillating pectoral fins (OPFs) and control it to accomplish vivid stable 3-D motions using central pattern generators (CPGs) and fuzzy algorithm.

Design/methodology/approach

The cownose ray’s asymmetric sine-like oscillations were analyzed. Then a cownose-ray-like fish robot named Robo-ray was developed, which has paired flexible multi-fin-ray OPFs to actively control the fin shape and two tail fins to control the depth. To solve the problem of coordinated control for multi-degree-of-freedom Robo-ray, CPGs were adopted. An improved phase oscillator as a CPG unit with controlled amplitude, phase lag, smooth frequency transition and asymmetric oscillation characteristic was established. Furthermore, the CPG-fuzzy algorithm was developed for vivid stable 3-D motions. The open-loop speed control, the closed-loop control of depth and yaw were established.

Findings

The kinematic comparisons indicate that Robo-ray imitates the cownose ray realistically. The experimental results of closed-loop are obtained that the depth error of Robo-ray is less than ±100 mm and the course error is less than ±3°. Furthermore, the comprehensive experiments demonstrate that Robo-ray has high mobility, stability and robustness.

Originality/value

This research makes the fish robot with OPF propulsion closer to practical applications in complex underwater environment, for instance, ocean explorations, water quality monitoring and stealth military reconnaissance. In addition, Robo-ray can be taken as a scientific tool for better understanding of the hydrodynamics of OPF batoid.

Details

Industrial Robot: the international journal of robotics research and application, vol. 46 no. 6
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 12 October 2018

Haroun Ragueb and Kacem Mansouri

The purpose of this study is to investigate the thermal response of the laminar non-Newtonian fluid flow in elliptical duct subjected to a third-kind boundary condition with a…

Abstract

Purpose

The purpose of this study is to investigate the thermal response of the laminar non-Newtonian fluid flow in elliptical duct subjected to a third-kind boundary condition with a particular interest to a non-Newtonian nanofluid case. The effects of Biot number, aspect ratio and fluid flow behavior index on the heat transfer have been examined carefully.

Design/methodology/approach

First, the mathematical problem has been formulated in dimensionless form, and then the curvilinear elliptical coordinates transform is applied to transform the original elliptical shape of the duct to an equivalent rectangular numerical domain. This transformation has been adopted to overcome the inherent mathematical deficiency due to the dependence of the ellipsis contour on the variables x and y. The yielded problem has been successfully solved using the dynamic alternating direction implicit method. With the available temperature field, several parameters have been computed for the analysis purpose such as bulk temperature, Nusselt number and heat transfer coefficient.

Findings

The results showed that the use of elliptical duct enhances significantly the heat transfer coefficient and reduces the duct’s length needed to achieve the thermal equilibrium. For some cases, the reduction in the duct’s length can reach almost 50 per cent compared to the circular pipe. In addition, the analysis of the non-Newtonian nanofluid case showed that the addition of nanoparticles to the base fluid improves the heat transfer coefficient up to 25 per cent. The combination of using an elliptical duct and the addition of nanoparticles has a spectacular effect on the overall heat transfer coefficient with an enhancement of 50-70 per cent. From the engineering applications view, the results demonstrate the potential of elliptical duct in building light-weighted compact shell-and-tube heat exchangers.

Originality/value

A complete investigation of the heat transfer of a fully developed laminar flow of power law fluids in elliptical ducts subject to the convective boundary condition with application to non-Newtonian nanofluids is addressed.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 1 September 1947

A.H. Yates

THE problem of designing an aircraft so that the pilot is able easily to regain and maintain control following the sudden failure of an engine has been for some years a serious…

Abstract

THE problem of designing an aircraft so that the pilot is able easily to regain and maintain control following the sudden failure of an engine has been for some years a serious one. It is thought that an elementary description of the aerodynamics of the problem and of the flight tests which are made to assess a particular aircraft may be of interest. The equally important problem of ensuring adequate performance after an engine failure is not discussed here.

Details

Aircraft Engineering and Aerospace Technology, vol. 19 no. 9
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 24 January 2020

Nayhel Sharma and Rakesh Kumar

The purpose of this paper is to establish a freestream computational fluid dynamics (CFD) model of a three-dimensional non-spinning semi-cylindrical missile model with a single…

Abstract

Purpose

The purpose of this paper is to establish a freestream computational fluid dynamics (CFD) model of a three-dimensional non-spinning semi-cylindrical missile model with a single wrap around fin in Mach 2.70-3.00M range and 0° angle of attack, and ultimately establishing itself for future research study.

Design/methodology/approach

In this study, the behaviour of flow around the fin was investigated using a κ-ϵ turbulence model of second-order of discretization. This was done using a highly structured mesh. Additionally, an inviscid CFD simulation involving the same boundary conditions have also been carried out for comparison.

Findings

The obtained values of aerodynamic coefficients and pressure contours visualizations are compared against their experimental and computational counterparts. A typical missile aerodynamic characteristic trend can be seen in the current CFD.

Practical implications

The predicted values of the aerodynamic coefficients of this single fin model have also been compared to those of the full missile body comprising of four fins from the previous research studies, and a similar aerodynamic trend can be seen.

Originality/value

This study explores the possibility of the use of turbulence modelling in a single fin model of a missile and provides a basic computational model for further understanding the flow behaviour near the fin.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 3
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 December 1950

F/Sgt Pilot I.

IN recent years the problems involved in flight on asymmetric power have attracted increasing attention and curiosity. It is safe to state that at the beginning of the British era…

Abstract

IN recent years the problems involved in flight on asymmetric power have attracted increasing attention and curiosity. It is safe to state that at the beginning of the British era of high‐powered twin‐engined aircraft, of which the Blenheim I is a representative type, pilots regarded an engine failure at any time as a major problem. A failure of the worst type—on take‐off—was thought to result invariably in loss of control, with the attendant after‐effects on aircraft and crew.

Details

Aircraft Engineering and Aerospace Technology, vol. 22 no. 12
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 April 1945

A.R. Weyl

THE complexity of the problems which are associated with the lateral stability and directional control of tailless aeroplanes was not realized until rather late.

Abstract

THE complexity of the problems which are associated with the lateral stability and directional control of tailless aeroplanes was not realized until rather late.

Details

Aircraft Engineering and Aerospace Technology, vol. 17 no. 4
Type: Research Article
ISSN: 0002-2667

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