Papers by Itimad D J Azzawi
Medwell Journals, 2019
Many used materials are available around us which can be produced useful devices, especially in t... more Many used materials are available around us which can be produced useful devices, especially in the field of electricity generation. Hybrid devices are one of these machines. Especially, that operate on renewable energy such as (solar, wind, water, etc.). Recently, there has been a lot of research that is particularly combining wind and solar energy as complementary to each other. Iraq has enough of this combined energy with natural potential of the astronomical location between the land and water and the climate factor which made it a region of the passage of wind through the year when the wind speed reached more than 5 m/sec in addition to solar energy. In is the study, it was built and developed Hybrid of Solar-Wind Turbine system (HSWT) with relying on simple and low-cost component.
In this paper the concept of active flow control using an array of synthetic jet actuators has be... more In this paper the concept of active flow control using an array of synthetic jet actuators has been investigated. Synthetic jets are the one type of actuators that will be used in this research to introduce important modification to the pressure distribution levels that appear over the lifting surface of airfoil model when the flow separation exists. Two synthetic jet actuators arrays were used; the first one placed at 3% c and the second array located at 6% c on the upper surface of a NACA0015 airfoil. The experiments are conducted at Re=455000 in 8 different angles of attack 0o to 15o using the wind tunnel at University of Diyala. The first part of this paper concentrates on making comparison of the collected experimental data of the pressure distribution over NACA0015 airfoil at Re = 4.4x10 at angle of attack varied from 0.0 to 20 degrees without synthetic jet actuators (baseline case study) and previous experimental results as a baseline validation of the onset of flow separatio...
Journal of Thermal Engineering, 2020
The effect on the dynamic stability of combustors with and without flame holders were investigate... more The effect on the dynamic stability of combustors with and without flame holders were investigated experimentally and computationally with thermal loads of 3, 5, and 9 kW. Three different cases were studied, large flame holder (LFH), small flame holder (SFH) and no flame holder (NO_ FH). Flame topology was investigated in these three cases. Moreover, lean propane–air premixed combustion were also considered for two models, turbulent flame speed closure (TFC) and coherent flame (CFM). These models were investigated using different turbulent kinetic energies and turbulence dissipation rates. Experiments were performed with mean inlet velocities of 16.5, 17, 29.2, 30.8, and 52.6 cm/s, excess air ratios (λ) of 1.6, 1.65, 1.7, and 1.8. The results showed that the flame topology and location are more sensitive to the increase in the excess air ratios and thermal loads in the large flame holder than in the small flame holder. Heat transfers and species distributions caused by combustion ar...
Journal of Heat Transfer-transactions of The Asme, 2020
2018 1st International Scientific Conference of Engineering Sciences - 3rd Scientific Conference of Engineering Science (ISCES), 2018
The present study aims to investigate the effect of the contraction profile on the flow quality s... more The present study aims to investigate the effect of the contraction profile on the flow quality such as the turbulent intensity, flow uniformity and pressure compared to baseline case (existing one). Primarily, losses of every wind tunnel part should be calculated. Hence, the total pressure losses of the whole wind tunnel circuit can be determined and all these losses are added up. This technique is required to evaluate the required power to operate the wind tunnel. As result, this method is well-suited with both of opened and closed-circuit wind tunnels. Moreover, two different profiles of the contraction are compared to the baseline wind tunnel (existing one) using the Computational Fluid Dynamics (CFD) as a basis for the comparison and analysis of the airflow properties through the whole wind tunnel design. The necessary parameters are the flow conditions within the test section that included the velocity, turbulent intensity and flow uniformity as well as the pressure distributi...
International Journal of Heat and Technology
A computational fluid dynamics (CFD) study was conducted to analyse the flow structure and the ef... more A computational fluid dynamics (CFD) study was conducted to analyse the flow structure and the effect of varying the coil pitch on the coil friction factor and wall shear stress, through utilising different models’ configurations. Three coils were tested, all of them having the same diameter and coil diameter: 0.005m and 0.04m respectively. Pitch variations began with 0.01, 0.05, 0.25 m for the first, second and third model respectively. Two turbulence models, STD(k-ϵ) and STD(k-w), were utilised in this simulation in order to determine the turbulence model which could capture most of the flow characteristics. A comparison was made between the STD(k-ϵ) and STD(k-w) models in order to analyse the pros and cons of each model. The results were validated with Ito’s equation for turbulent flow and compared with Filonenko’s equation for a straight pipe. The governing equations were discretized using finite volumes method and the SIMPLE algorithm was used to solve the equations iteratively...
Thermoacoustic engines and coolers are a promising emerging technology due to its environmental f... more Thermoacoustic engines and coolers are a promising emerging technology due to its environmental friendliness and the lack of mechanical moving parts. Acoustic-to-electrical (or vice versa) transduction devices are the key components allowing for the conversion between acoustic (i.e. mechanical) and electrical energies (or vice versa). Some of researchers investigated the use of acoustic drivers in their devices due to their high acoustic power and transduction efficiency. This paper focuses on the performance analysis of a few selected acoustic drivers, available commercially, in order to provide a better understanding of their efficient utilisation in the context of coupling with thermoacoustic machines (engines or refrigerators). Six different acoustic drivers where studied using analytical solutions. The selected drivers have widely varied specifications which leads to major differences (in terms of ultimate performance) when various acoustic conditions are applied to simulate the presence of different thermoacoustic networks. Such investigation could lead to better engineering practices in coupling the drivers to thermoacoustic systems and positively influence their overall efficiency. Therefore, this study is thought to be beneficial design engineers working on thermoacoustic machines.
International Journal of Heat and Technology
Experimental investigations of the flows inside helically coiled pipe are difficult and may also ... more Experimental investigations of the flows inside helically coiled pipe are difficult and may also be expensive, particularly for small diameters. Computational fluid dynamics (CFD) packages, which can easily construct the geometry and change the dimensions with 100% of accuracy, provide an alternative solution for the experimental difficulties and uncertainties. Therefore, a computational fluid dynamics (CFD) study was conducted to analyse the flow structure and the effect of varying the coil pitch on the coil friction factor and wall shear stress, through utilising different models' configurations. Three coils were tested, all of them sharing the same pipe and coil diameter: 0.005m and 0.04m respectively. Pitch variations began with 0.01, 0.05, 0.25 m for the first, second and third model respectively. In this study, the pressure drop was analysed, and the effects of this reduction on wall shear stress and coil friction factor were also examined using incompressible viscous laminar flow to elucidate the effect of varying coil pitch on the friction factor and wall shear stress. The results were validated by Ito's equation for the laminar flow and compared with the Hagen-Poiseuille resistance formula for a straight pipe.
IOP Conference Series: Materials Science and Engineering
The study aims tray to improve the performance of the Al-Mansourieh gas power plant located in Ir... more The study aims tray to improve the performance of the Al-Mansourieh gas power plant located in Iraq with a production (4 ×732 MW). By proposing a new (cooling/heating) system for air that entering the compressor by using groundwater (well water) as a renewable energy. FCU-Unit system operates according to the annual season. The calculations for the study was carried out in two stages, the first one included the thermodynamic analysis of the proposed system and finding the optimal design of space for heat exchanger. By another calculation, the amount of cooling water it was between (14.5 - 87) kg / s and the rate of airflow that reached (1.87m3/h). While the second part of this study included calculating the ideal and actual efficiency through the introduction of the actual conditions for the work of the turbine which took into account the pressure losses in the turbine inlet, exhaust pressure losses, combustion chamber pressure losses, combustion efficiency, and compressor and turbi...
Journal of Heat Transfer
The use of porous media (PM) to improve conductive heat transfer has been at the focus of interes... more The use of porous media (PM) to improve conductive heat transfer has been at the focus of interest in recent years. Limited studies, however, have focused on heat transfer in radial heat sinks (RHSs) fully and partially saturated porous media with a different arrangement. As a development of the above-mentioned investigations, this research, therefore, addresses the ability of radial porous heat sink solutions to improve the thermohydraulic characteristics and reduce the effect of the second thermodynamics law. The response surface methodology (RSM) technique with ansysfluent-cfd is utilized to optimize the thermohydraulic features and the total entropy generation by the multi-objective optimum design for different design parameters such as porosity (Ø), inlet temperature (Tin), and applied heat flux (Q) simultaneously after achieving the optimum porous media arrangement related to the flow direction. The results show that, in terms of the flow direction, the optimum radial porous h...
Journal of Engineering and Applied Sciences
Journal of Mechanical Engineering Research and Developments
International Journal of Air-Conditioning and Refrigeration
Ordinary refrigeration systems such as vapor-compression refrigerators are the commonly used devi... more Ordinary refrigeration systems such as vapor-compression refrigerators are the commonly used devices in industry, mostly for their high efficiencies. However, they make a significant contribution to the depletion of Ozone and global warming due to their operational refrigerants. Hence, thermoacoustic refrigeration can be a great alternative candidate which uses inert gases such as air, helium and nitrogen as the primary refrigerant. Thermoacoustic refrigerators convert the acoustic power (sound waves) into a thermal effect (cooling power). Thermoacoustics can be counted as a new technology that has a strong potential toward the development of the thermal applications. This study aims to design and fabricate miniaturized traveling wave thermoacoustic refrigerator which can be driven by an ordinary loudspeaker. The optimized numerical design of the refrigerator shows an overall efficiency (cooling power over input electricity) of nearly 66% at a temperature difference of 25[Formula: s...
Journal of Fluids Engineering
There is generally limited guidance available on the optimum clamping method for the diaphragms u... more There is generally limited guidance available on the optimum clamping method for the diaphragms used in the synthetic jet actuators (SJAs). This paper describes the effects of clamping methods (O-rings, neoprene rubber washers and metal-to-metal clamping) on the actuator diaphragm displacement using Polytec scan vibrometer (PSV). Once the clamping type was implemented, an optimization study to examine the effect of geometrical parameters for three designs of synthetic jet actuators in quiescent conditions—in particular the number of orifices per cavity, the space between them, and their effects on the jet velocity—was performed. It has also been shown that with use the Helmholtz resonance of the cavity and amplitude modulation of the excitation signal, the actuator can exhibit a more significant “blowing” velocity at a reduced power input.
Miniaturized Traveling-Wave Thermoacoustic Refrigerator Driven by Loudspeaker: Numerical Design, 2020
Ordinary refrigeration systems such as vapor-compression refrigerators are the commonly used devi... more Ordinary refrigeration systems such as vapor-compression refrigerators are the commonly used devices in industry, mostly for their high e±ciencies. However, they make a signi¯cant contribution to the depletion of Ozone and global warming due to their operational refrigerants. Hence, thermoacoustic refrigeration can be a great alternative candidate which uses inert gases such as air, helium and nitrogen as the primary refrigerant. Thermoacoustic refrigerators convert the acoustic power (sound waves) into a thermal e®ect (cooling power). Thermoacoustics can be counted as a new technology that has a strong potential toward the development of the thermal applications. This study aims to design and fabricate miniaturized traveling wave thermoacoustic refrigerator which can be driven by an ordinary loudspeaker. The optimized numerical design of the refrigerator shows an overall e±ciency (cooling power over input electricity) of nearly 66% at a temperature di®erence of 25K (between cold an...
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Papers by Itimad D J Azzawi