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Fluid flows in pipes whose cross-sectional area are increasing in the stream-wise direction are prone to separation of the recirculation region. This paper aims to investigate such fluid flow in expansion pipe systems using direct numerical simulations. The flow in circular diverging pipes with different diverging half angles, namely, 45, 26, 14, 7.2 and 4.7 degrees, are considered. The flow is fed by a fully developed laminar parabolic velocity profile at its inlet and is connected to a long straight circular pipe at its downstream to characterise recirculation zone and skin friction coefficient in the laminar regime. The flow is considered linearly stable for Reynolds numbers sufficiently below natural transition. A perturbation is added to the inlet fully developed laminar velocity profile to test the flow response to finite amplitude disturbances and to characterise sub-critical transition.

Direct numerical simulations of the Navier–Stokes equations have been solved using a spectral element method.

It is found that the onset of disordered motion and the dynamics of the localised turbulence patch are controlled by the Reynolds number, the perturbation amplitude and the half angle of the pipe.

The authors clarify different stages of flow behaviour under the finite amplitude perturbations and shed more light to flow physics such as existence of Kelvin–Helmholtz instabilities as well as mechanism of turbulent puff shedding in diverging pipe flows.

A modelling approach of gas solid flow, considering different physical phenomenon such as fluid turbulence, particle turbulence and interparticle collision effects are presented. The approach is based on the two‐fluid model formulation where both phases are treated as continuum. This implies that the gas phase as well as the particle phase are weighted by their separate volumetric fractions. According to the experimental results and numerical simulations, the inter‐particle collision possesses a significant influence of turbulence level on particle transport properties in gas solid turbulent flow even for dispersed phase volume fraction (α<0.01). Comparisons in predictions have been depicted with inclusion of interparticle collision effect in the equation of particle turbulent kinetic energy and with exclusion of this effect. Experimental research has been conducted in a thermal power plant depicting higher erosion resistance of noncircular square sectioned coal pipe bends in comparison with those with circular cross section, the salient features of the experimental work are presented in this paper. Experiments have been conducted to determine, pressure drop in straight and curved portions of conduits conveying air coal mixtures in a thermal power plant. Validation of this experimental data with numerical predictions have been presented.

This article aims to study numerically three dimensional developing incompressible flow and heat transfer in a fixed curved pipe.

A projection algorithm based on the second order finite difference method is used for discretizing governing equations written in the toroidal coordinate system.

The effects of curvature and governing non‐dimensional parameters consisting of Reynolds, Prandtl, and Dean numbers on the flow field, entrance length, and heat transfer are studied in detail. The numerical results indicate that the entrance length depends only on the Reynolds number for the curvature ratios greater than 1/7 and therefore, Dean number is not a pertinent parameter in this range.

For heat transfer analysis, two different thermal boundary conditions, i.e. constant wall temperature and constant heat flux at the wall are implemented. The results are calculated for the Dean numbers in the range of 76‐522 and for the two prandtl numbers of 0.5 and 1.

The results can be used in designing heat exchangers, piping systems, and cooling of gas turbine blades.

The numerical results obtained here concentrate on the detailed investigation of flow and temperature field at the entrance region by a quantitative analysis of hydrodynamic and thermal entrance length. The effects of different thermal boundary conditions and different inlet profiles on the flow and temperature fields are studied in the circular curved pipe for the first time.

A numerical study of a quantitative analogy of fully developed turbulent flow in a straight square duct rotating about an axis perpendicular to that of the duct and a stationary curved duct of square cross‐section was carried out. In order to compare the two flows, the dimensionless parameters K_TR=Re^1/4/√Ro and the Rossby number, Ro=w_m/Ωd_h, in the rotating straight duct flow corresponded to K_TC=Re^1/4/√λ and the curvature ratio, λ=R/d_h, in the stationary curved duct flow, so that they had the same dynamical meaning as those parameters for fully developed laminar flow. For the large values of Ro or λ, the flow field satisfied the “asymptotic invariance property”; there were strong quantitative similarities between the two flows, such as in the flow patterns and friction factors for the same values of K_TR and K_TC. Based on these similarities, it is possible to predict the flow characteristics in rotating ducts by considering the flow in stationary curved ducts, and vice versa.

This report, in two volumes (text and tables and diagrams), gives the results of an attempt to determine the relative values of the principal factors governing the power of engines at different heights, with a view to the determination of the laws governing the power drop with altitude, thus providing reliable bases for comparisons.

A theoretical study is performed on three‐dimensional, heat transfer and fluid flow in radially rotating heated channels with steady, laminar throughflow. Consideration is given to the channel of different geometry. Both the rotational speed and throughflow rate are varied. The flow is hydrodynamically and thermally developing, with a constant wall heat flux. The velocity‐vorticity method is employed in the formulation and numerical results are obtained by means of a finite‐difference technique. The Nusselt number, friction factor, and temperature and velocity distributions are determined, and the role of the Coriolis force on the entrance‐region transport phenomena is investigated. Results are compared with the existing literature.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics, and publications of other similar research bodies as issued

The purpose of this paper is to describe the design and construction of a custom‐built low‐cost thermal vacuum chamber (TVC) for spacecraft environmental testing and verification. The paper provides detailed analysis and an insight into the design and development of the chamber. The chamber was specifically constructed for carrying out the thermal and vacuum environmental tests in a 16″ dia × 16″ long horizontal thermal vacuum chamber. The chamber is constructed using a combination of mechanical (roughing) pump and turbo‐molecular pump, used to pump the chamber down to 10⁻⁵ Torr and a combination of radiation heaters and nitrogen gas is used to vary the temperature within the chamber from +80 to −50°C.

The TVC equipment is built as part of the picosatellite and nanosatellite program at Space Systems Research Laboratory of Saint Louis University. The equipment is built at a low cost and is suited for testing an entire picosatellite and several components and subsystems of nanosatellite simulating thermal and vacuum conditions similar to space environment. The different main parts of the equipment are described in a way which explains the choice of construction and partly makes it possible to replicate similar equipment.

The TVC equipment is successfully used to simulate the thermal and vacuum conditions of space similar to the conditions experienced by a picosatellite or nanosatellite in low earth orbit.

The design and construction of TVC in this paper have broader implications and can be a platform for future research on low‐cost TVC. This equipment can be utilized in the research areas of electronics and communications, biology and medicine to name a few. Thermal and vacuum experiments on several astro‐biological experiments can be performed.

The paper is intended to be a source of inspiration for industrial or academic space research laboratories which would like to design and construct a similar test‐equipment, instead of investing expensive commercially available alternatives.

The paper discusses in detail, the simplified cost‐effective approach of constructing TVC and also outlines the various issues to be considered. The TVC equipment is custom‐built and is described in an easily understandable way, which makes this a helpful paper for those who wish to produce similar equipment. This will be the only known manuscript in the literature to detail the design and construction of low‐cost, economical TVC.

The purpose of this study is to explore the transient characteristics of mixed-flow pumps during startup process.

This study uses a full-flow field transient calculation method of mixed-flow pump based on a closed-loop model.

The findings show the hydraulic losses and internal flow characteristics of the piping system during the start-up process.

Large computational cost.

Improve the accuracy of current numerical simulation results in transient process of mixed-flow pump.

Simplify the setting of boundary conditions in the transient calculation.

A method is presented for the determination of heat transfer rates in cylindrical cooling ducts which rotate about an axis orthogonal to its own axis of symmetry. The equations of motion and energy are solved in conjunction with the two equation model of turbulence (k—ε) using the finite element method. The importance of employing consistent velocity and turbulence quantities is demonstrated; the former condition is particularly relevant with respect to induced secondary flows. It was also found that comparatively minor mesh refinement had a significant effect on both the flow and the increase in heat transfer rates over those obtained for the non‐rotating case.