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The purpose of this paper, computational fluid dynamics (CFD) work, is to promote turbulent thermal convection in a heated circular tube using a passive scheme of a slotted twisted sheet.

The inventive design uses square-cut and conjugate triangular perforations to diversify the twisted tape for better thermal convection. The current novel passive scheme methodology is accomplished by carving the same square cuts and slitting various sizes of equilateral triangle perforations (side length varies between 8 and 16 mm). The re-normalisation group turbulence model and the semi-implicit method for pressure-linked equation method examine the turbulent thermal convection aspects of all simulations at different Reynolds numbers (6,000, 10,000 and 14,000).

The analyses of simulations exhibit that the placement of a twisted tape with triangle perforations and equidistant square cuts can effectually promote thermal convection in a circular tube. A larger-sized triangle perforation can increase the thermal convection enhancement and thermal performance factor, but an enlarged perforation may decrease the thermal convection enhancement and thermal performance factor. As a result, compared with the smooth circular tube, the circular tube with the slotted twisted sheet slit by a 10 mm equilateral triangle brings about the maximum improvement ratio of the mean Nusselt number of about 2.8 at Re = 6,000. Under weighing the friction through the circular tube, the tube with the slotted twisted sheet slit by a 10 mm equilateral triangle gains the best thermal performance factor of about 1.36 at Re = 6,000.

The working fluid is water and its physical features are assumed to be constant. In addition, the fluid is considered a steady flow in this CFD work.

These CFD predictions will benefit the development of heat exchanger tubes equipped with a slotted twisted sheet to acquire preferable thermal convection enhancement.

Higher thermal performance achieved by placing a slotted twisted tape in a heated tube will benefit society in lower energy consumption, machinery maintenance costs and impact on the environment.

This study combined triangle perforations and square cuts on the twisted sheet. This combination can induce the fluid flow across the sheet to disturb the swirling flow and then promote the fluid mixing to increase thermal convection. Therefore, this modified tape can be a profitable passive device for designing a heat exchanger.

The purpose of the study is to propose a novel implementation of twisted tape in sinusoidal wavy-walled tubes to enhance the rate of heat transfer without compromising thermal efficiency. The study numerically investigates the fluid flow characteristics and analyzes the effect of different geometrical configurations, including wall wave amplitude, tape twist angles and nanoparticle volume fractions, on heat transfer improvement and performance factor.

This problem is numerically investigated using computational fluid dynamics, and the method is the finite volume method. A two-phase mixture model is used for nanofluid modeling.

The study investigated the effect of wall waviness, twisted tape, and nanoparticles on forced convective heat transfer and friction factor behavior in laminar pipe flow in three different Reynolds number regimes. The results showed that implementing twisted tape in wavy tubes significantly increased the rate of heat transfer and the performance factor, with the best twist ratio between 90 and 180°. Adding nanoparticles also enhanced heat transfer and performance factor, but to a lesser extent than wavy wall-twisted tape combinations. The study suggests selecting a proper combination of wavy wall and twisted tape at each Reynolds number to achieve an optimum solution.

To the best of the authors’ knowledge, the implementation of the selected passive methods in sinusoidal wavy tubes has not been studied before, and no previous studies have taken into account such a mix of heat transfer improvement techniques.

The purpose of this study is to advance turbulent thermal convection inside the constant heat-flux round tube inserted by multiple perforated twisted tapes.

The novel design of this study is accomplished by inserting several twisted tapes and drilling some circular perforations near the tape edge (C1, C3, C5: solid tapes; C2, C4, C6: perforated tapes). The turbulence flow appearances and thermal convective features are examined for various Reynolds numbers (8,000–14,000) using the renormalization group (RNG) κ−ε turbulent model and Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm.

The simulated outcomes reveal that inserting more perforated-twisted tapes into the heated round tube promotes turbulent thermal convection effectively. A swirling flow caused by the twisted tapes to produce the secondary flow jets between two reverse-spin tapes can combine with the main flow passing through the perforations at the outer edge to enhance the vortex flow. The primary factors are the quantity of twisted tapes and with/without perforations, as the perforation ratio remains at 2.5 in this numerical work. Weighing friction along the tube, C6 (four reverse-spin perforated-twisted tapes) brings the uppermost thermal-hydraulic performance of 1.23 under Re = 8,000.

The constant thermo-hydraulic attributes of liquid water and the steady Newtonian fluid are research limitations for this simulated work.

The simulated outcomes will avail the inner-pipe design of a heat exchanger inserted by multiple perforated twisted tapes to enhance superior heat transfer.

These twisted tapes form tiny circular perforations along the tape edge to introduce the fluid flow through these bores and combine with the secondary flow induced between two reverse-spin tapes. This scheme enhances the swirling flow, turbulence intensity and fluid mixing to advance thermal convection since larger perforations cannot produce large jet velocity or the position of perforations is too far from the tape edge to generate a separated flow. Consequently, this work contributes a valuable cooling mechanism toward thermal engineering.

Equipment, Programmes, Techniques and Projects. Variable‐pitch drop‐out ram air turbines which provide a stand‐by electrical or hydraulic power supply in an emergency on VC10 and Trident airliners, are being tested at Dowty Rotol Ltd.'s Gloucester plant by an ingenious technique using a stroboscope in conjunction with a closed‐circuit television system, both supplied by EMI Electronics Ltd.

AS a member of a Rolls‐Royce team of engineers I have been engaged upon the study of the cause of turbine blade failure on the test‐bed and in flight, but I should like to mention here that the views expressed in this paper are entirely my own and do not necessarily represent the views or the policy of Rolls‐Royce Limited. I have not hesitated to put forward some views, although the data are not available at this stage to provide rigid proofs that the views are correct. I hope that in doing this I may add to the interest of the discussion that will follow this paper.

IN a recent address Mr. S. J. Noel‐Brown, a work study consultant who is frequently called in by local authorities, said that 209 such bodies, out of a total of 1,800, had shown a lively interest in the subject. Of these many used outside consultants or had joined in group schemes. Some authorities, however, were still living in the quill pen era, scarcely having heard of typewriters. They were struggling along with laborious, out‐of‐date equipment.

THERE ARE MANY people — far too many people, in our opinion — who are ready to state, or maybe just to agree, that manufacturers in other countries have the edge on us, whether in design or technology or even on price. On top of that, those same people, as a rule, are quick to condemn British workers as lazy, slow and ready to strike at the drop of a hat. We do not subscribe to any of this.

Words like Participation tend to be labels stuck on generalities, signifying nothing. They are used as verbal bromides by publicists anxious to cover harsh realities with an attractive veneer. As a rule, once they have served their purpose, they are conveniently forgotten.

MR. R. A. Butler's remark about doubling our living standards within the next twenty‐five years has a secure place in contemporary political obiter dicta. It suffers from being the kind of comment that is remembered long after any qualifying context has been forgotten.

THAT is the title of a survey by the National Joint Advisory Council which has just been issued by the Ministry of Labour. Properly assimilated by both sides of industry it could become an important document for a country continually under pressure to increase productivity. In his Foreword the Minister of Labour says that the number of manual workers engaged on a shift system has increased by more than half in the last ten years and expects the trend to continue.