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Article
Publication date: 5 January 2023

Sandeep Rangrao Desai and Mangalsing Narsing Sonare

The prediction of critical velocity at instability threshold for shell and tube heat exchangers is important to avoid failure of tubes as a result of flow-induced vibrations due…

63

Abstract

Purpose

The prediction of critical velocity at instability threshold for shell and tube heat exchangers is important to avoid failure of tubes as a result of flow-induced vibrations due to water cross flow. The flow-induced vibration in finned tube heat exchangers is affected by various parameters such as fin height, fin pitch, fin material, tube array, pitch ratio, fin type, fluid velocity etc. In this paper, an experimental investigation of fluid elastic instability in shell and tube heat exchangers is carried out by subjecting normal square finned tube arrays of pitch ratio 1.79 to water cross flow.

Design/methodology/approach

The five tube arrays, namely plain array, two finned tube arrays with 3 fpi and 9 fpi fin density, and two finned tube arrays with 3 mm and 6 mm fin height are tested in the experimental test setup with water flow loop and vibration measurement system. The research objective is to evaluate the effect of fin density and fin height on the instability threshold. The critical velocity at instability threshold is determined to characterize the fluid elastic instability behavior of different tube arrays. The vortex shedding behavior of the tube arrays is also studied by determining Strouhal number corresponding to the small peaks before fluid elastic instability.

Findings

The fluid elastic instability behavior of the tube arrays was found to be the function of fin tube parameters. The experimental results indicate that an increase in fin density and fin height results in delaying the instability threshold for finned tube arrays. It is also observed that critical velocity at instability is increased for finned tube arrays compared to plain tube arrays of the same pitch ratio. The design modifications in the outer box have resulted in further reduction in the natural frequency. This enabled to reach clear instability for all the five-tube arrays.

Originality/value

The research data add the value to the present body of knowledge by knowing the effect of fin height and fin density on the fluid elastic instability threshold of normal square finned tube arrays subjected to water cross flow.

Details

Multidiscipline Modeling in Materials and Structures, vol. 19 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 19 June 2019

K. Gobi, B. Kannapiran, D. Devaraj and K. Valarmathi

In Aerospace applications, the inlet tubes are used to mount strain gauge type pressure sensors on the engine under static test to measure engine chamber pressure. This paper aims…

102

Abstract

Purpose

In Aerospace applications, the inlet tubes are used to mount strain gauge type pressure sensors on the engine under static test to measure engine chamber pressure. This paper aims to focus on the limitations of the inlet tube and its design aspects to serve better in the static test environment. The different sizes of the inlet tubes are designed to meet the static test and safety requirements. This paper presents the performance evaluation of the designed inlet tubes with calibration results and the selection criteria of the inlet tube to measure combustion chamber pressure with the specified accuracy during static testing of engines.

Design/methodology/approach

Two sensors, specifically, one cavity type pressure sensor with the inlet tube of range 0-6.89 MPa having natural frequency of the diaphragm 17 KHz and another flush diaphragm type pressure sensor of the same range having −3 dB frequency response, 5 KHz are mounted on the same pressure port of the engine under static test to study the shortcomings of the inlet tube. The limitations of the inlet tube have been analyzed to aid the tube design. The different sizes of inlet tubes are designed, fabricated and tested to study the effect of the inlet tube on the performance of the pressure sensor. The dynamic calibration is used for this purpose. The dynamic parameters of the sensor with the designed tubes are calculated and analyzed to meet the static test requirements. The diaphragm temperature test is conducted on the representative hardware of pressure sensor with and without inlet tube to analyze the effect of the inlet tube against the temperature error. The inlet tube design is validated through the static test to gain confidence on measurement.

Findings

The cavity type pressure sensor failed to capture the pressure peak, whereas the flush diaphragm type pressure sensor captured the pressure peak of the engine under a static test. From the static test data and dynamic calibration results, the bandwidth of cavity type sensor with tube is much lower than the required bandwidth (five times the bandwidth of the measurand), and hence, the cavity type sensor did not capture the pressure peak data. The dynamic calibration results of the pressure sensor with and without an inlet tube show that the reduction of the bandwidth of the pressure sensor is mainly due to the inlet tube. From the analysis of dynamic calibration results of the sensor with the designed inlet tubes of different sizes, it is shown that the bandwidth of the pressure sensor decreases as the tube length increases. The bandwidth of the pressure sensor with tube increases as the tube inner diameter increases. The tube with a larger diameter leads to a mounting problem. The inlet tube of dimensions 6 × 4 × 50 mm is selected as it helps to overcome the mounting problem with the required bandwidth. From the static test data acquired using the pressure sensor with the selected inlet tube, it is shown that the selected tube aids the sensor to measure the pressure peak accurately. The designed inlet tube limits the diaphragm temperature within the compensated temperature of the sensor for 5.2 s from the firing of the engine.

Originality/value

Most studies of pressure sensor focus on the design of a sensor to measure static and slow varying pressure, but not on the transient pressure measurement and the design of the inlet tube. This paper presents the limitations of the inlet tube against the bandwidth requirement and recommends dynamic calibration of the sensor to evaluate the bandwidth of the sensor with the inlet tube. In this paper, the design aspects of the inlet tube and its effect on the bandwidth of the pressure sensor and the temperature error of the measured pressure values are presented with experimental results. The calibration results of the inlet tubes with different configurations are analyzed to select the best geometry of the tube and the selected tube is validated in the static test environment.

Details

Sensor Review, vol. 39 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 23 March 2012

Alfin Leo, Gino Rinaldi, Ion Stiharu and Rama Bhat

It is currently difficult to measure temperature and pressure in harsh environments. Such measurements are limited by either the ability of the sensing element or the associated…

Abstract

Purpose

It is currently difficult to measure temperature and pressure in harsh environments. Such measurements are limited by either the ability of the sensing element or the associated electrical wiring to withstand the operating environment. This is unfortunate as temperature and pressure are important measurands in various engineering structures as they provide critical information on the operating condition of the structure. Hence, there is a need to address this shortcoming. Such a sensor in place would enhance the operating efficiency thereby reducing the pollution burden and its impact on the environment. The purpose of this paper is to present theoretical and preliminary experimental results for a co‐integrated pressure and temperature sensor for harsh environments.

Design/methodology/approach

This work describes a co‐integrated pressure‐temperature wireless sensing scheme. The approach presented herein provides the possibility of measuring dynamic pressure and temperature within an enclosed volume using acoustic signals. Resonance tube physics is exploited for the temperature sensing. A microphone is used to obtain the acoustic signal whose frequency is a function of the temperature and the tube geometry.

Findings

The dynamic pressure is measured from the calibrated amplitude of the pressure wave signal measured by the microphone. The temperature can be measured through the shift of the standing wave frequency with a resolution of <1°C. The resonance tube can be fabricated using any material that resists harsh environments. The geometry of the tube can be tailored for any specific frequency range, as the application warrants. Also, this provides a means for accurate temperature compensation of pressure sensor data from high temperature environments. A Matlab/Simulink model is developed and presented for the acquisition of acoustic signals through the wall of an enclosed volume. For these applications the standing wave signal transmitted through the enclosure wall becomes a function of the wall material and wall thickness. Preliminary experimental results are presented in which a DC fan is used for generating the dynamic pressure in a varying temperature environment.

Research limitations/implications

The major issue is the separation of the noise from the signal. As various applications yield specific signal noise, the problem needs detailed data to be addressed.

Practical implications

Temperature and dynamic pressure could be recorded/monitored in very harsh environment conditions such as chemical reactors.

Originality/value

This work demonstrates the possibility of employing a co‐integrated acoustic sensing scheme in which both pressure and temperature are measured simultaneously with a sole sensor. The major advantage with acoustic sensing is the wireless transmission of data. This allows for non‐invasive measurement from within enclosed systems. Direct real‐time temperature compensation is possible that does not require any compensation circuitry. Hence, pressure and temperature data may be obtained from caustic operating environments whose access is otherwise not feasible.

Article
Publication date: 3 February 2023

Josué Costa-Baptista, Edith Roland Fotsing, Jacky Mardjono, Daniel Therriault and Annie Ross

The purpose of this paper is the design and experimental investigation of compact hybrid sound-absorbing materials presenting low-frequency and broadband sound absorption.

Abstract

Purpose

The purpose of this paper is the design and experimental investigation of compact hybrid sound-absorbing materials presenting low-frequency and broadband sound absorption.

Design/methodology/approach

The hybrid materials combine microchannels and helical tubes. Microchannels provide broadband sound absorption in the middle frequency range. Helical tubes provide low-frequency absorption. Optimal configurations of microchannels are used and analytical equations are developed to guide the design of the helical tubes. Nine hybrid materials with 30 mm thickness are produced via additive manufacturing. They are combinations of one-, two- and four-layer microchannels and helical tubes with 110, 151 and 250 mm length. The sound absorption coefficient of the hybrid materials is measured using an impedance tube.

Findings

The type of microchannels (i.e. one, two or four layers), the number of rotations and the number of tubes are key parameters affecting the acoustic performance. For instance, in the 500 Hz octave band (α500), sound absorption of a 30 mm thick hybrid material can reach 0.52 which is 5.7 times higher than the α500 of a typical periodic porous material with the same thickness. Moreover, the broadband sound absorption for mid-frequencies is reasonably high with and α1000 > 0.7. The ratio of first absorption peak wavelength to structure thickness λ/T can reach 17, which is characteristic of deep-subwavelength behaviour.

Originality/value

The concept and experimental validation of a compact hybrid material combining a periodic porous structure such as microchannels and long helical tubes are original. The ability to increase low-frequency sound absorption at constant depth is an asset for applications where volume and weight are constraints.

Details

Rapid Prototyping Journal, vol. 29 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 13 November 2009

Shuhong Liu, Jianqiang Mai, Jie Shao and Yulin Wu

The purpose of this paper is to predict pressure pulsation in Kaplan hydraulic turbines.

Abstract

Purpose

The purpose of this paper is to predict pressure pulsation in Kaplan hydraulic turbines.

Design/methodology/approach

State of the art numerical simulation techniques are employed to simulate three‐dimensional flows in the whole flow passage of a Kaplan turbine so that pressure pulsations can be computed in both time domain and frequency domain. Numerical results are verified by experiments carried out on the most advanced experimental platform in China.

Findings

It is found that the proposed numerical model is a viable tool for prediction of pressure pulsations. The simulation shows that the model turbine and prototype turbine have the same pressure pulsation frequencies and rotating frequencies and the same transmission patterns under similar operation conditions. However, there is no similarity for the amplitude of the pressure pulsation between the model turbine and the prototype turbine. Therefore pressure pulsations in a prototype turbine cannot be obtained by scaling the experimental results of the model turbine using a similarity relationship.

Practical implications

The findings will be very valuable for the design of hydraulic turbines and large‐scale hydraulic power stations.

Originality/value

The proposed numerical method provides a viable tool for hydraulic turbine and power station designers to predict the pressure pulsations in prototype turbines. It is a useful tool to help improve the performance of hydraulic turbines. The findings made in the numerical simulation have been verified by experiments, which is also a valuable reference for hydraulic turbine designers.

Details

Engineering Computations, vol. 26 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 June 1972

R.J. Sidwell

Rapid advances in ultrasonics have provided plant engineers with a powerful aid in the fight to control corrosion. This article outlines the principles, design and selection of…

Abstract

Rapid advances in ultrasonics have provided plant engineers with a powerful aid in the fight to control corrosion. This article outlines the principles, design and selection of ultrasonic gauges.

Details

Anti-Corrosion Methods and Materials, vol. 19 no. 6
Type: Research Article
ISSN: 0003-5599

Article
Publication date: 1 May 1942

Alexander Klemin

IN our report of the tenth annual meeting of the Institute of the Aeronautical Sciences we shall not follow precisely the order in which the sessions occurred nor at all times…

Abstract

IN our report of the tenth annual meeting of the Institute of the Aeronautical Sciences we shall not follow precisely the order in which the sessions occurred nor at all times classify the papers in exactly the manner of the meeting. Unfortunately, certain of the papers presented will not be found in our review owing to lack of preprints, but this in no way reflects on the value or timeliness of the papers omitted in the review.

Details

Aircraft Engineering and Aerospace Technology, vol. 14 no. 5
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 6 July 2015

L.K. Tartibu, B. Sun and M.A.E. Kaunda

This paper aims to illustrate the use of the augmented epsilon-constraint method implemented in general algebraic modelling system (GAMS), aimed at optimizing the geometry of a…

Abstract

Purpose

This paper aims to illustrate the use of the augmented epsilon-constraint method implemented in general algebraic modelling system (GAMS), aimed at optimizing the geometry of a thermoacoustic regenerator. Thermoacoustic heat engines provide a practical solution to the problem of heat management where heat can be pumped or spot cooling can be produced. However, the most inhibiting characteristic of thermoacoustic cooling is their current lack of efficiencies.

Design/methodology/approach

Lexicographic optimization is presented as an alternative optimization technique to the common used weighting methods. This approach establishes a hierarchical order among all the optimization objectives instead of giving them a specific (and most of the time, arbitrary) weight.

Findings

A practical example is given, in a hypothetical scenario, showing how the proposed optimization technique may help thermoacoustic regenerator designers to identify Pareto optimal solutions when dealing with geometric parameters. This study highlights the fact that the geometrical parameters are interdependent, which support the use of a multi-objective approach for optimization in thermoacoustic.

Originality/value

The research output from this paper can be a valuable resource to support designers in building efficient thermoacoustic device. The research illustrates the use of a lexicographic optimization to provide more meaningful results describing the geometry of thermoacoustic regenerator. It applies the epsilon-constraint method (AUGMENCON) to solve a five-criteria mixed integer non-linear problem implemented in GAMS (GAM software).

Article
Publication date: 5 April 2019

Corrado Groth, Ubaldo Cella, Emiliano Costa and Marco Evangelos Biancolini

This paper aims to present a fast and effective approach to tackle complex fluid structure interaction problems that are relevant for the aeronautical design.

Abstract

Purpose

This paper aims to present a fast and effective approach to tackle complex fluid structure interaction problems that are relevant for the aeronautical design.

Design/methodology/approach

High fidelity computer-aided engineering models (computational fluid dynamics [CFD] and computational structural mechanics) are coupled by embedding modal shapes into the CFD solver using RBF mesh morphing.

Findings

The theoretical framework is first explained and its use is then demonstrated with a review of applications including both steady and unsteady cases. Different flow and structural solvers are considered to showcase the portability of the concept.

Practical implications

The method is flexible and can be used for the simulation of complex scenarios, including components vibrations induced by external devices, as in the case of flapping wings.

Originality/value

The computation mesh of the CFD model becomes parametric with respect to the modal shape and, so, capable to self-adapt to the loads exerted by the surrounding fluid both for steady and transient numerical studies.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 6
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 February 1962

P.O.A.L. Davies

ALTHOUGH the University of Southampton has had an independent existence for ten years it has roots going back almost a century in the Hartley Institute. An early pioneer in…

Abstract

ALTHOUGH the University of Southampton has had an independent existence for ten years it has roots going back almost a century in the Hartley Institute. An early pioneer in aeronautics, F. W. Lanchester received his technical training in Southampton and the first of the new engineering buildings at the university has been called after him.

Details

Aircraft Engineering and Aerospace Technology, vol. 34 no. 2
Type: Research Article
ISSN: 0002-2667

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