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A high-pressure ratio and a wide operating range are highly required for a turbocharger in diesel engines. Ring groove arrangement is effective for flow range enhancement of centrifugal compressors. Two ring grooves on the suction pipe and the shroud casing wall are connected by means of the annular passage, and the stable recirculation flow is formed at small flow rates from the downstream groove toward the upstream groove through the annular bypass. It is well known that the ring groove arrangement shows the following two merits; (1) the formation of recirculation flow removes the low energy fluid around the downstream groove located near the splitter blade leading edge, (2) the flow incidence can be reduced because the recirculation flow merges again with the incoming main flow upstream of the impeller inlet. In the present study, the ring groove arrangement was applied to the high speed centrifugal compressor, in addition, in order to suppress too large pre-whirl due to the recirculation flow, the effects of guide vane installed in the annular passage and the ring groove configuration on the pre-whirl were analyzed numerically. The numerical flow analysis was carried out by using the commercial code produced by ANSYS-CFX. The simulation results show the multi-ring grooves are fairly effective in combination with the suitable configuration of guide vanes for improvement in the inlet velocity distortion., THE 10TH ASIAN INTERNATIONAL CONFERENCE ON FLUID MACHINERY : Kuala Lumpur (Malaysia), 21–23 October 2009, AIP Conference Proceedings, 1225, pp.47-54; 2010

Swirling fluid motion in enclosed chambers was studied using Computational Fluid Dynamics. Using the tangential inlet configuration as the basic design, 3 swirl generator models was created using Computer Aided Design software. The aim was to see whether a modified design from the original configuration could provide a reduction in the backflow effect that is constantly present in swirling flows. Simulations show that swirl generator inlets at different angles from the original tangential position results in a change in velocity profiles across the flow cross section. From the simulations performed, it was found that the swirl generator model with inlets set to 45 degrees produced the least backflow compared to other models.

Bent ducts add loss and decrease efficiency. Many researchers have conducted the performances of bent ducts, but their shapes of inlet and outlet are same. However, the bent duct which has different shape of inlet and outlet has not been investigated. In this investigation, the focus is on a bent duct which is annular at the inlet and circular at the outlet. The performance of such bent duct is investigated under inlet speed of 54 m/s and Reynolds number of 238,000. Wall static pressure tappings are located on the surface of the bent duct to measure the static pressure. 5hole probe is traversed at the inlet and outlet of the bent duct to measure the flow. To investigate the flow in the bent duct, computational fluid dynamics (CFD) is conducted in this study. As a result, it presents static pressure distribution on the bent duct surface, streamwise velocity profile of the bent duct and total pressure loss profile at outlet of the bent duct. Flow field at outlet of the bent duct has 3 distinctive regions; two separations regions due to inner pipe and curvature of the bent duct and one core of houseshoe shape.

High speed liquid jets may be applied to jet cutting, drilling and cleaning. Recently, in the automotive industries, the spray injection pressure becomes higher and higher to enhance the fuel mixing for the improved combustion efficiency. However, the ultra high injection pressure may cause the damage to the nozzle and also the combustion chamber. In the medical application, the high speed liquid injection might be applied for the drug delivery through the skin where the needle is not required anymore. From the above mentioned application, the investigation on the impact pressure of the high speed liquid jet relative to the stand‐off distant is significant. The high speed liquid jets are generated by the projectile impact driven method. The high speed projectile is launched by the horizontal single stage powder gun. The experimental study focuses on the stand‐off between 1.5 cm to 6.0 cm, while the nozzle contains approximately 1.5cm3 of water in its cavity. The nozzle conical angles are 30° and 60° with ...

Waste wood is used as feedstock for Universiti Teknologi Malaysia’s newly‐developed two‐stage incinerator system. The research goals are to optimize the operation of the thermal system to the primary chamber, to improve its combustion efficiency and to minimize its pollutants formation. The combustion process is evaluated with the variation of fuel’s moisture content. For optimum operating condition, where the gasification efficiency is 95.53%, the moisture content of the fuel is best set at 17%; giving outlet operating temperature of 550°C and exhaust gas concentrations with 1213 ppm of CO, 6% of CO2 and 14% of O2 respectively. In line to the experimental work, a computational fluid dynamics software, Fluent is used to simulate the performance of the primary chamber. Here the predicted optimum gasification efficiency stands at 95.49% with CO, CO2 and O2 concentrations as 1301 ppm, 6.5% and 13.5% respectively.

Experimental and numerical investigations were conducted for the internal flow of the stator of the diagonal flow fan. Corner separation near the hub surface and the suction surface of the stator blade are focused on. At low flow rate of 80% of the design flow rate, the corner separation between the suction surface and the hub surface can be found in both experimental and numerical results. Separation vortices are found in the computed oil flow on both suction and hub surfaces at 80% of the design flow rate in the three‐dimensional numerical simulation.

For the next leap in the sustainable energy exploitations, we are under obligations not only to cope with the warming global environment but also to conserve natural ecosystems and to coexist with natures. This paper introduces the following advanced technologies in Kyushu Institute of Technology, to utilize effectively the promising ocean and wind resources at the offshore. (1) Counter‐Rotating Type Reversible Hydroelectric Unit, which is composed of the tandem runners and the peculiar generator with the double rotational armatures, is applicable to both rising and falling tides at the power station with the embankment, in place of the traditional bulb type turbines. (2) Gyro‐Type Reversible Hydraulic Turbine, which is composed of some blades with the high aspect ratio, is effective to utilize the tide power even at the shallow and/or the very low range of the tide. (3) Submerged Ocean Wave Power Unit, where a pair of floats is lined up at the interval of one wave pitch and supports the vertical type hyd...

Fluidized bed type heat exchangers are known to increase the heat transfer and prevent the fouling. For proper design of circulating fluidized bed heat exchanger it is important to know the effect of design and operating parameters on the bed to the wall heat transfer coefficient. The present experimental and numerical study was conducted to investigate the effects of circulating solid particles on the characteristics of fluid flow, heat transfer and cleaning effect in the fluidized bed vertical shell and tube type heat exchanger with counterflow, at which a variety of solid particles such as glass (3 mmF), aluminum (2∼3 mmF), steel (2∼2.5 mmF), copper (2.5 mmF) and sand (2∼4 mmF) were used in the fluidized bed with a smooth tube. Seven different solid particles have the same volume, and the effects of various parameters such as water flow rates, particle diameter, materials and geometry were investigated. The present experimental and numerical results showed that the flow velocity range for collision of ...

Three‐dimensional numerical simulations are carried out to investigate the amount of heat transfer of a plain fin‐and‐four staggered layout and round tube rows for different fin pitch namely 25.4, 12.7, 6.35 and 4.23 mm. The simulations were conducted for two different frost thermal conductivity of 0.1 and 0.3 W/m‐1K‐1 using FLUENT 6.3 CFD code. The amount of heat transfer of the plain fin‐and‐round tube heat exchanger under frost condition (0, 1, 2, and 3 mm frost thickness) was investigated. Fluid flow and heat transfer are simulated and results calculated using two turbulence models (k‐epsilon, and Transitional SST k‐omega), with steady‐state solver. Model validation was carried out by comparing the pressure drop of simulated case to experimental results from the literature. Reasonable agreement was found between the present simulations compared to existing numerical study and experimental data.

An experimental study of impulse produced by a pulse combustion tube was done to compare between the methods of pendulum and accelerometer for impulse measurement. Stoichiometric mixtures of methane and propane were studied with varying dilution percentages of Nitrogen. Without obstacles, all mixtures exhibit deflagration. To induce detonation, obstacles were used. Detonation occurred for dilution percentage of 42% and lower. From the results, pendulum method always gives higher impulse measurement in deflagration regime while the accelerometer method gives higher results for detonation. The accelerometer method is not suitable for deflagration due to inaccuracies in determining pressure peaks from the measurement. However, it is suitable for studying individual pulses in detonation due to the presence of distinct pressure peaks.

Turbo‐pumps have weak points, such as the pumping operation becomes unstable in the rising portion of the head characteristics and/or the cavitation occurs at the low suction head. To overcome simultaneously both weak points, the authors invented the unique pump unit composed of the tandem impellers and the counter‐rotating type motor with the double rotational armatures. The front and the rear impellers are driven by the inner and the outer armatures of the motor, respectively. Both impeller speeds are automatically and smartly adjusted in response to the pumping discharge. Such speeds controlled smartly contribute pretty well to suppress not only the unstable performances at the low discharge but also the cavitation at the high discharge, as verified in the previous paper.Continuously, the effects of the impeller profiles not only on the pump performances but also on the rotational behaviors are discussed in this paper. Two kinds of the blade profile, giving the lower and the higher heads, were prepared as the front and the rear impellers. The pump performances and the both impeller speeds are affected undoubtedly by not only the discharge but also the impeller profiles. The rotational speed of the front impeller is faster than the speed of the rear impeller in the wide discharge, while the tandem impellers composed of the front impeller giving the lower head and the rear impeller giving the higher head. Such behaviors are caused by making the angular momentum change through the front impeller coincide with that through the rear impeller.

A Nonlinear Programming Model for the optimal day‐operation of multi‐units pump in one pumping station by adjusting blade angle has been put out, where the peak‐valley electricity prices is considered in this paper. The model takes the minimal operation cost of pump assembly as objective function. In the meantime, the periods are defined as stage variables. The blade angle and the number of the working‐pumps are expressed as decision variables and the water volume pumped in one day as constraint condition. The problem is very difficult to be settled by regular methods. This paper presents a new method which adopts experimental optimization method of adjusting blade angle in different periods and linear integral programming method to select the number of pumps. After applying the method to the optimal operation of Jiangdu No.4 pumping station, which is the source pump station of Eastern Route Project of South‐to‐North Water Diversion(Where there are seven pumps and the design flow rate of single‐unit is 30...

In this paper, design optimization for mixed‐flow pump impellers and diffusers has been studied by using a commercial CFD code and DOE(design of experiments). We also discussed how to improve the performance of the mixed‐flow pump by designing the impeller and diffuser in the mixed‐flow pump. Geometric design variables were defined by the vane plane development which indicates the blade‐angle distributions and length of the impeller and the diffusers. The vane plane development was controlled by using blade‐angle in a fixed meridional shape. First the design optimization of the defined impeller geometric variables was done, and then the flow characteristics were analyzed in the point of incidence angle at the diffuser leading edge for the optimized impeller. Then design optimizations of the defined diffuser shape variables were performed. The importance of the geometric design variables was analyzed by using 2k factorial designs, and the design optimization of the geometric variables were determined using...

In this study, aeroelastic response analyses have been conducted for a 3D MW‐Class wind turbine blade model. The complex composite laminated blade rotates in the unsteady fluid. Advanced computational fluid dynamics (CFD) and computational multi‐body dynamics (CMBD) coupling method has been developed in order to investigate aeroelastic responses of the rotating composite blade in unsteady fluid. Reynolds‐Averaged Navier‐Stokes (RANS) equations with k‐e turbulence model were solved for unsteady flow problems of the rotating turbine blade model, and modal analyses of rotating wind‐turbine blade have been conducted by using the general nonlinear finite element program. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3D turbine blade for fluid‐structure interaction (FSI) problems. Detailed dynamic responses and instantaneous velocity contour on the blade surfaces which considering flow‐separation effe...

The development of a tidal current turbine that can extract maximum energy from the tidal current will be extremely beneficial for supplying continuous electric power. The present paper presents a conceptual design of a 100kW energy integrated type tidal current turbine for tidal power generation. The instantaneous power density of a flowing fluid incident on an underwater turbine is proportional to the cubic power of current velocity which is approximately 2.5m/s. A cross‐flow turbine, provided with a nozzle and a diffuser, is designed and analyzed. The potential advantages of ducted and diffuser‐augmented turbines were taken into consideration in order to achieve higher output at a relatively low speed. This study looks at a cross‐flow turbine system which is placed in an augmentation channel to generate electricity bi‐directionally. The compatibility of this turbine system is verified using a commercial CFD code, ANSYSCFX. This paper presents the results of the numerical analysis in terms of pressure, ...

In the present study, the authors conduct subsonic wind‐tunnel experiments, in order to investigate the effect of a depth‐to‐width ratio λ upon the tumbling of a simple two‐dimensional rectangular‐cross‐section prism. The authors carry out both flow visualisation and velocity measurement using a hot‐wire anemometer, together with the synchronised measurement of a prism’s attack angle α, which are analised using a phase‐averaging technique. As a result, there are two modes for λ

The rotary dryer with agitator is an apparatus that combines convection drying as hot air and rotary drying with agitator. One of the important design factors to decide the drying efficiency is inside flow characteristics of the chamber. It depends on shape, material, rotational velocity of impeller and velocity of hot air. In this study, we calculated flow fields in dryer chamber with various conditions by a commercial CFD code, ANSYS CFX. Because inside flow of dryer chamber is consisted of hot air and vapor, we performed two‐phase numerical analyses. Especially, we obtained the volume fraction distribution inside chamber under unsteady and turbulence flow conditions.

Presented in this paper are a fan’s aero‐acoustic performance method and its computation procedure which combines aerodynamic flow field data, performances and noise levels of fan. The internal flow field and the performance of fan are analyzed by the through‐flow modeling, inviscid pitch‐averaged quasi‐3D flow analysis combined with flow deviation and pressure loss distribution models. Based on the predicted internal flow field dada by the trough‐flow modeling, fan noise is predicted by two models for the discrete frequency noise due to rotating steady aerodynamic thrust and blade interaction and for the broadband noise due to turbulent boundary layer and wake vortex shedding. The present predictions of the flow distribution, the performance and the noise level of fan are well agreed with actual test results.

Thermoacoustic phenomenon is a new alternative refrigeration technology. Though design and fabrication is complex for getting the desired effect, it is environmentally friendly and successful system showed that it is relatively easy to run compared to the traditional vapor compression refrigeration system. Currently, theories supporting the thermoacoustic refrigeration systems are yet to be comprehensive to make them commercially viable. Theoretical, experimental, and numerical studies are being done to address the thermodynamics‐acoustics interactions. In this study, experimental investigations were completed to test the feasibility of the practical use of a thermoacoustic refrigerator in its counter‐top form for future specific application. The system was designed and fabricated based on linear acoustic theory. Acoustic power was given by a loud speaker and thermoacoustic effects were measured in terms of the cooling effects produced at resonanance. Investigations showed that discrepancies between desig...

New advances in micro and nano scales are being realized and the contributions of micro and nano heat dissipation devices are of high importance in this novel technology development. Past studies showed that microchannel design depends on its thermal resistance and pressure drop. However, entropy generation minimization (EGM) as a new optimization theory stated that the rate of entropy generation should be also optimized. Application of EGM in microchannel heat sink design is reviewed and discussed in this paper. Latest principles for deriving the entropy generation relations are discussed to present how this approach can be achieved. An optimization procedure using EGM method with the entropy generation rate is derived for a circular microchannel heat sink based upon thermal resistance and pressure drop. The equations are solved using MATLAB and the obtained results are compared to similar past studies. The effects of channel diameter, number of channels, heat flux, and pumping power on the entropy gener...

In this paper, an improved lattice Boltzmann scheme is used to simulate steady incompressible flow inside a square cavity. The newly improved scheme is applied for driven square cavity. Numerical simulations are carried out for Reynolds number equal to 5000. The governing equation used is the double‐population lattice Boltzmann formulation. On the other hand, two‐dimensional nine velocity model is used for the computation of velocity field. The results obtained are compared with the results found in the literature reviews. Moreover, the time needed for the solution to converge is recorded. The time obtained is compared with the time required for the conventional lattice Boltzmann scheme to converge. Present study found that the computation time can be reduced without sacrificing the accuracy of the results.

Hydro Power is the most important renewable energy source on earth. The water is free of charge and with the generation of electric energy in a Hydroelectric Power station the production of green house gases (mainly CO2) is negligible. Hydro Power Generation Stations are long term installations and can be used for 50 years and more, care must be taken to guarantee a smooth and safe operation over the years. Maintenance is necessary and critical parts of the machines have to be replaced if necessary. Within modern engineering the numerical flow simulation plays an important role in order to optimize the hydraulic turbine in conjunction with connected components of the plant. Especially for rehabilitation and upgrading existing Power Plants important point of concern are to predict the power output of turbine, to achieve maximum hydraulic efficiency, to avoid or to minimize cavitations, to avoid or to minimized vibrations in whole range operation. Flow simulation can help to solve operational problems and t...

Dynamic behaviors of fluid flow and interaction with the pipe material as well as the temperature are very useful in the design of heat exchangers. The information can be used to determine the effective operating condition and the limitation of the heat exchanger which will then benefited the manufacturers and consumers in terms of economy and safety. A single pass cross flow heat exchanger with conduction and forced convection heat transfer was represented by a mathematical model consist sets of partial differential equations. The equations were then transformed to non‐dimensional form for the solution. A computer program was developed to solve the problem numerically. The governing equations were solved by finite difference method using implicit method. Five different types of refrigerant were used in the study; water, R‐134a, R‐23, R‐22 and ammonia. Time response for steady state temperature then was determined and compared between the refrigerants which were then shows that ammonia has the shortest ti...

This paper presents experimental and Computational Fluids Dynamics (CFD) investigations of the flow in ventilated brake discs. Development of an experiment rig with basic measuring devices are detailed out and following a validation study, the possible improvement in the brake cooling can be further analyzed using CFD analysis. The mass flow rate is determined from basic flow measurement technique following that the conventional bi‐directional passenger car is simulated using commercial CFD software FLUENT™. The CFD simulation is used to investigate the flow characteristics in between blade flow of the bi‐directional ventilated disc brake.

In this paper, lattice Boltzmann scheme is used to simulate steady incompressible flow inside a square cavity. Numerical simulations are carried out for Reynolds number of 100, 400, 1000, 3200 and 7500. The governing equation use is the double‐population lattice Boltzmann formulation. Two‐dimensional nine velocity model is used for the computation of velocity field. The results obtained are compared with the results found in the literature reviews. Present study found that lattice Boltzmann scheme is able to carry out equivalent results as conventional scheme.

This study investigated on details of flow characteristics of a multi‐blade fan for domestic ventilation. Experiments and analysis were carried out to describe on flow pattern with variations of cut‐off angle near the scroll‐housing throat, which were performed by PIV measurement for the flow field and by total pressure probes. The stagnation point at cut‐off region of the fan moves to the exit of the scroll housing as cut‐off angle increases. The movement of stagnation point and the variation of throat area of the scroll housing influence to the distribution of velocity magnitude at the exit of the fan. Furthermore, a large distortion of the velocity distribution at the scroll exit causes to increase mixing loss along the flow path. The improvement of the fan design on cut‐off is expected through understanding the flow pattern.

In order to reduce the axial thrust of centrifugal pump, the J‐Groove (shallow and wide groove along the pressure gradient) is put on the casing wall. With adequate shape of the grooves, the axial thrust can be reduced about 38% at the best efficiency point, and much more at the partial discharge area. Other performances such as head coefficient and power coefficient are not changed at all by the grooves. Also the flow of the whole pump including the gaps in which the leak flow goes through is calculated by CFD tool, and its result shows the relation of flow near the groove and the degree of reducing of axial thrust.

For a CO2 heat pump water heater, one‐stage twin rotary compressor has been designed. As a design tool, computer simulation program for the compressor performance has been made. Validation of the simulation program has been carried out for a bench model compressor in a compressor calorimeter. Cooling capacity and the compressor input power were reasonably well compared between the simulation and the calorimeter test. Good agreement on P‐V diagram between the simulation and the test was also obtained. With this validated compressor simulation program, parametric study has been performed to arrive at optimum dimensions for the compression chamber.

This paper presents the simulation of natural heat convection in an enclosure problem using the lattice Boltzmann method. D2Q9 lattice model was coupled with the simplest D2Q4 lattice model to represent density and internal energy distribution function respectively. The effect of the Rayleigh number on the flow pattern in an enclosure filled with air heated by localized small source of heat at bottom wall was studied. The results explain the mechanism of natural convection rate increasing due to the Rayleigh number increasing. The comparison of the results was in excellent agreement with experimental results from literatures.

2‐D driven cavity flow is the widely studied benchmark problem by many researchers of computational fluid dynamics field in terms of accuracy, numerical efficiency and others. Lattice Boltzmann Method (LBM) is one of the numerical methods for simulating this type of flow. For solving cavity flow with high Reynolds Number, the saving in time consumption is really appreciated. Therefore, as the initial study, averaging method for reducing CPU time has been proposed for solving lid driven cavity flow with low Reynolds Number. The results show that the averaging method can save time consumed for simulation. For instance, in the case of Reynolds Number 80, the proposed averaging method can save about 12% of the original CPU time (without averaging method).

The aerodynamic characteristics of airfoils have been researched in higher Reynolds‐number ranges more than 106, in a historic context closely related with airplanes’ and fluid‐machinery developments in the last century, however our knowledge is not enough at low and middle Reynolds‐number ranges. So, in the present study, we investigate such basic airfoils as a NACA0015, a flat plate and the flat plates with modified fore‐face and after‐facegeometries in a Reynolds‐number range of 102–105, using two‐ and three‐dimensional computations together with wind‐tunnel and water‐tank experiments. Especially, we show their flow fields at Re = 1.0×102.

The present study investigates local heat/mass transfer characteristics on blade tip surface with squealer rim. A linear cascade experimental setup consists of three large scale airfoils was used. The axial chord length and turning angle of test blade are 237 mm and 126°, respectively. Heat/mass transfer coefficients were measured with three different rim heights (3%, 6% and 9% of axial chord length) and fixed tip clearance (2% of axial chord length). Main flow Reynolds number based on axial chord length is 1.5×105. Naphthalene sublimation method is used to measure the detailed mass transfer coefficient on the blade tip surface. The heat/mass transfer results show that as the rim height increases, the peak values on the upstream region of the tip surface decreases and moves to the suction side rim. At the downstream region of the tip surface, the pitch‐wise averaged heat/mass transfer coefficients increases as the rim height increases.

Whirling motion of a pump impeller was calculated for the centrifugal blood pump with Conical Spiral Groove Bearings to get a criterion for the instability of impeller whirling motion. The motion of the centrifugal blood pump impeller was calculated based on a spring damping model, and unsteady flow in the pump was computed using the commercial CFD package ANSYS CFX. Also the whirling motion of rotating impeller was measured using two displacement sensors fixed to the blood pump casing. The numerical calculations were done for the blood pump impeller with conical spiral groove bearings, and impeller whirling motion was evaluated.

Increasing energy demand coupled with pollution free production of energy has found a viable solution in wind energy. Land based windmills have been utilized for power generation for more than two thousand years. In modern times wind generated power has become popular in many countries. Offshore wind turbines are being used in a number of countries to tap the energy from wind over the oceans and convert to electric energy. The advantages of offshore wind turbines as compared to land are that offshore winds flow at higher speed than onshore winds and the more available space. In some land based settings, for better efficiency, turbines are separated as much as 10 rotor diameters from each other. In offshore applications where only two wind directions are likely to predominate, the distances between the turbines arranged in a line can be shortened to as little as two or four rotor diameters. Today, more than a dozen offshore European wind facilities with turbine ratings of 450 kw to 3.6 MW exist offshore in very shallow waters of 5 to 12 m. Compared to onshore wind turbines, offshore wind turbines are bigger and the tower height in offshore are in the range of 60 to 80 m. The water depths in oceans where offshore turbines can be located are within 30 m. However as the distance from land increases, the costs of building and maintaining the turbines and transmitting the power back to shore also increase sharply. The objective of this paper is to review the parameters of design for the maximum efficiency of offshore wind turbines and to develop types offshore towers to support the wind turbines. The methodology of design of offshore towers to support the wind turbine would be given and the environmental loads for the design of the towers would be calculated for specific cases. The marine corrosion on the towers and the methods to control the corrosion also would be briefly presented. As the wind speeds tend to increase with distance from the shore, turbines build father offshore will be able to capture more wind energy. Currently two types of towers are considered. Cylindrical tubular structures and truss type structures. But truss type structures have less weight and flexibility in design. The construction of the offshore towers to harness the wind energy is also presented. The results will include the calculation of wind and wave forces on the tower and the design details for the tower.

We attempt to reveal the unsteady three‐dimensional flow structure in a suction sump with the vertical‐wet‐pit‐pump configuration. In the present study, we consider the simultaneous measurement of a three‐dimensional particle tracking velocimetry (3D‐PTV) with another velocimetry, that is, an ultrasonic velocity profiler (UVP), using common tracer particles. This simultaneous measurement is expected to be a suitable method for the accuracy check of the 3D‐PTV. At first, we have successfully found the suitable condition for simultaneous measurements with high accuracy. Then, we have revealed the concerning unsteady three‐dimensional flow structure at various instants, quantitatively.

The primary aim of this research is to investigate the possibilities of using ring as bluff body for the flame stabilization. The second objective is to study the flame characteristics by changing the parameters such as different types of bluff body, the equivalent ratio for the fuel and the different ratio of Reynolds numbers. From the observation, the stability region for the different type of bluff body depends on the two main parameters namely Reynolds number and the equivalence ratio. By using a bluff body, reacting fluid can be stabilized without being attached to the burner port. Otherwise without the ring the reacting fluids will be stabilized at the burner port when it propagates.

The labyrinth seal is one of non‐contact seals, which is used as a seal device of rotary machines from reasons of the lubrication free and small losses. So far, many researchers have investigated the characteristics and suitable geometries of labyrinth seals, though only one directional flow of the seal has been focused up to now. As flow direction in the seal becomes changeable depending on the gas‐purge system and the inner pressure variation of machines for recent applications, a guideline of designing labyrinth seal with changeable flow directions is required. In the present report, effects of seal characteristics and internal flow behaviors on various shapes of asymmetric convexity in labyrinth seals are experimentally investigated and relations between pressure loss and convexity geometries are discussed for designing a suitable seal.

Three‐dimensional flows through a Low Speed Research Axial Compressor were numerically conducted in order to estimate the performance through unsteady and steady‐state simulations. The first stage with the inlet guide vane was investigated at the design point to confirm that the rotor blade induced periodicity exists. Special attention was paid to the flow near the stall condition to inspect the flow behavior in the vicinity of the stall margin. The performance predicted under the steady‐state assumption is in good agreement with the measured data. However, the steady‐state calculations induce more blockage through the blade passage. Flow separations on the blade surface and end‐walls are reduced when unsteady simulation is conducted. The negative jet due to the wake of the rotor blade periodically distorts the boundary layer on the surface of the stator blade and improves the performance of the compressor in terms of the pressure rise. The advantage of the unsteadiness increases as the flow rate reduces. In addition, the rotor tip leakage flow is forced downstream by the unsteadiness. Consequently, the behavior contributes to extending the range of operation by preventing the leakage flow from proceeding upstream near the stall margin.

The best efficiency point is ideal operational point for any turbomachinery. Selections of turbomachines in industry such as pump, turbine, compressor, etc are basically based on their operating point. The best efficiency point is a point at the highest efficiency. Therefore, turbomachines with nearest operating point to best efficiency point will be chosen due to higher efficiency thus produce great reduction in cost saving. Different speed of rotor blade will cause effect to the best efficiency point, as well as different in rotor and stator blade angle. If angle of rotor and stator blade constant while speed of rotor blade increased, the net head produced by the compressor will also increased. Thus, it will increase the brake horse power and fluid horse power. Although the efficiency of the compressor increases if fluid horse power increased, the increasing in brake horse power will produce lower efficiency. In this paper, the effect of rotor blade speed on best efficiency point of an axial flow compre...

Venturi has been widely used for measuring flow rate in a variety of engineering applications since pressure loss is relatively small compared with other measuring method. The current study focuses on making detailed estimation of measured uncertainties as the upstream turbulence affects uncertainty levels of the water flows in the closed‐loop testing. Upstream turbulences can be controlled by selecting 9 different swirl generators. Measurement uncertainty of flow rate has been estimated by a quantitative uncertainty analysis which is based on the ANSI/ASME PTC 19.1–2005 standard. The best way to reduce error in measuring flow rate was investigated for evaluating its measurement uncertainty. The results of flow rate uncertainty analysis show that the case with systematic error has higher than that without systematic error. Especially the result with systematic error exhibits that the uncertainty of flow rate was gradually increased by upstream turbulence. Uncertainty of flow rate measurement can be mainly affected by differential pressure and discharge coefficient. Flow disturbance can be also reduced by increasing of the upstream straight length of Venturi.

This research introduces the Duct Water Current Turbine Triple Helix with very low head less than 2m and water current at river or in the ocean, economical ecological use for small hydro power rating between 100 to 1000 kW still represents an unsolved problem. Unlike conventional hydro installation, water current turbine in open flow and generate power from flowing water with almost zero in environmental impact. Developments in water current turbine design are reviewed and some potential advantages of duct or “diffuser augmented” current turbine and extremely low head turbine will be explored. For the output expected from the project is helical turbine with control flow on duct. The research aims to apply the helical turbine inside the duct to find the parameter of the power coefficient against tip speed ratio λ, pitch angle and twist angle y which is also the optimum parameter to design a helical cross flow turbine with duct. Parameters are obtained from numerical simulation and through the experimental result. For ducted turbines the theoretical limit depends on (i) the pressure difference that can be created between duct inlet and outlet, and (ii) the volumetric flow through the duct.

In this paper, fluid flow behaviour of steady incompressible flow inside a triangular cavity was studied. Numerical calculations were done for three types of triangular cavity. The numerical investigations were conducted for different Reynolds numbers by using lattice Boltzmann scheme. The governing equation used is the double‐population lattice Boltzmann formulation. On the other hand, two‐dimensional nine velocity model was used for the computation of velocity field. The results obtained were compared with the results found in the literature reviews. Present study found that the flow patterns are significantly affected by the triangle geometry.

The authors have proposed the unique centrifugal pump, in which the impeller dose not have the driving shaft but is driven by the magnetic induction, namely Lorentz force, without the stay. Then, the rotating posture of the impeller is not stable, just like UFO. To make the rotating posture of the impeller stable irrespective of the operating condition, the pressure in the impeller casing was investigated experimentally while the impeller rotates at the steady state, as the preliminarily stage. The pressure, as well known, fluctuates periodically in response to the blade number. Besides, the pressure on the impeller shrouds decreases with the increase of the gap between the front shroud and the suction cover where the water leaks to the suction pipe, and is distorted in the peripheral direction. Such pressure conditions contribute directly to the hydraulic force acting on the impeller. The unstable behaviors of the impeller are induced from the above hydraulic forces, which change unsteadily in the radial and the peripheral directions in the impeller casing. The forces are affected by not only the operating condition but also the rotating posture of the impeller.

Flow meters, which are used for transferring water or crude oil through pipelines, require well‐defined flow conditions for accurate flow rate monitoring. Even though all the installation conditions for the flow meters are satisfied, there could be unexpected flow disturbances, such as abrupt increase of upstream pressure, affecting on the performance of flow meters. To investigate any differences between measured and actual flow rates, flow velocity profiles inside the pipeline must be known. Ultrasound tomography is a means of reconstructing flow profiles from line‐averaged velocities by Radon transformation. Diagnostic parameters are then extracted from the reconstructed flow profiles to give information whether the flow conditions are appropriate for accurate flow metering. In the present study, flow profiles downstream of a mass flow meter and a butterfly valve are reconstructed. Flow diagnostic parameters are defined using statistical moments such as mean value, standard deviation, skewness and kurtosis. The measured diagnostic parameters in the above‐mentioned flow conditions are compared with those of fully‐developed laminar and turbulent flow profiles to validate their usefulness.

Tenom Pangi Hydro Power Station in Tenom, Sabah is suffering from poor river quality with a lot of suspended trashes. This problem necessitates the need for a trash diverter to divert the trash away from the intake region. Previously, a trash diverter (called Trash Diverter I) was installed at the site but managed to survived for a short period of time due to an impact with huge log as a results of a heavy flood. In the current project, a second trash diverter structure is designed (called Trash Diverter II) with improved features compared to Trash Diverter I. The Computational Fluid Dynamics (CFD) analysis is done to evaluate the river flow interaction onto the trash diverter from the fluid flow point of view, Computational Fluids Dynamics is a numerical approach to solve fluid flow profile for different inlet conditions. In this work, the river geometry is modeled using commercial CFD code, FLUENT®. The computational model consists of Reynolds Averaged Navier‐Stokes (RANS) equations coupled with other related models using the properties of the fluids under investigation. The model is validated with site‐measurements done at Tenom Pangi Hydro Power Station. Different operating condition of river flow rate and weir opening is also considered. The optimum angle is determined in this simulation to further use the data for 3D simulation and structural analysis.

Design optimization is performed in this study for Pipe Flow Generator. Emphasize are on the impeller parameters including the geometry and the number of the blades. Modern engineering tools such as Computational‐Fluid‐Dynamics software and Rapid‐Prototyping technology are utilized, to facilitate both numerical and experimental studies. In CFD numerical simulation, two dimensional transient analyses are conducted to investigate the relationship between the flow rate and the blade geometry, as well as the number of the blades. During experimentation, Rapid Prototyping technology is used to fabricate more than 30 different blades for comparison. RPM and corresponding Voltages are measured for different impeller designs. The study leads to several important findings and the results are very informative for better design of the pipe flow generator.

The tempo‐spatial evolution of the combustion kernel in gas phase explosions was experimentally investigated using Schlieren photography. Methane and propane ‐air explosions were initiated in a cylindrical explosion vessel at a range of equivalence ratios ranging from 0.6 to 1.4. All explosions were initiated using 25 mj ignition energy at ambient conditions. The kernel growth rate, and cellular flame structure are observed and analyzed.

Auto detection of high level water content for oil well is a system that measures the percentage of water in crude oil. This paper aims to discuss an auto detection system for measuring the content of water level in crude oil which is applicable for offshore and onshore oil operations. Data regarding water level content from wells can be determined by using automation thus, well with high water level can be determined immediately whether to be closed or not from operations. Theoretically the system measures the percentage of two‐ fluid mixture where the fluids have different electrical conductivities which are water and crude oil. The system made use of grid sensor which is a grid pattern like of horizontal and vertical wires. When water occupies the space at the intersection of vertical and horizontal wires, an electrical signal is detected which proved that water completed the circuit path in the system. The electrical signals are counted whereas the percentage of water is determined from the total electrical signals detected over electrical signals provided. Simulation of the system using the MultiSIM showed that the system provided the desired result.

The formation and development of a wing‐tip vortex in a near and extended near filed were studied experimentally. Particle image velocimetry was used in a wind tunnel to measure the tip vortex velocity field and hence investigate the flow structure in a wake of aircraft half‐wing model. The purpose of this investigation is to evaluate the main features of the lift generated vortices in order to find ways to alleviate hazardous wake vortex encounters for follower airplanes during start and approach such that the increase in airport capacity can be achieved. First the wake structure at successive downstream planes crosswise to the axis of the wake vortices was investigated by measuring parameters such as core radius, maximum tangential velocities, vorticities and circulation distributions. The effect of different angles of attack setting on vortex parameters was examined at one downstream location. In very early stages the vortex sheet evolution makes the tip vortex to move inward and to the suction side of the wing. While the core radius and circulation distributions hardly vary with the downstream distance, noticeable differences for the same vortex parameters at different angles of attack settings were observed. The center of the wing tip vortices scatter in a circle of radius nearly equal to 1% of the mean wing chord and wandering amplitudes shows no direct dependence on the vortex strength but linearly increase with the downstream distance.

Rocket propellant has been identified as a component that played an important role in the development of rockets. The ejected material in rocket propulsion is due to material called propellant. Without propellant, a rocket cannot be launched. Due to this reason, many have started to conduct research on new chemical compound of propellant with new technique if needed. The objectives of this study are to study the thermo‐chemistry aspect of the composition and to determine the burning characteristics parameters. For this reason, this dissertation presented a detail preparation of developing a solid propellant using Ammonium Perchlorate (AP) as an oxidizer, Aluminum (Al) as fuel and Hydroxyl Terminated Polybutadiene (HTPB) as the binder. To determine the propellant performance such as burning rate, testing was conducted. From testing result the propellant composition oxidizer‐fuel (76/11) at pressure 110 Psi gave the maximum burning rate. From test results the empirical constant, ‘a’ and pressure exponent ‘n’ were calculated for each different propellant compositions.