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Razi Nalim
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Item Air-Standard Aerothermodynamic Analysis of Gas Turbine Engines With Wave Rotor Combustion(2009-09) Nalim, M. Razi; Li, H; Akbari, PezhmanThe wave rotor combustor can significantly improve gas turbine engine performance by implementing constant-volume combustion. The periodically open and closed combustor complicates thermodynamic analysis. Key cycle parameters depend on complex gas dynamics. In this study, a consistent air-standard aerothermodynamic model with variable specific heat is established. An algebraic model of the dominant gas dynamics estimates fill fraction and internal wave compression for typical port designs, using a relevant flow Mach number to represent wave amplitudes. Nonlinear equations for thermodynamic state variables are solved numerically by Newton–Raphson iteration. Performance measures and key operating conditions are predicted, and a quasi-one-dimensional computational model is used to evaluate the usefulness of the algebraic model.Item Analytic Design Methods for Wave Rotor Cycles(1994-09) Resler, Edwin L.; Moscari, Jeffrey C.; Nalim, M. RaziA procedure to design a preliminary wave rotor cycle for any application is presented. To complete a cycle with heat addition there are two separate-but related-design steps that must be performed. Selection of a wave configuration determines the allowable amount of heat added in any case, and the ensuing wave pattern requires associated pressure discharge conditions to allow the process to be made cyclic. This procedure, when applied, gives a first estimate of the cycle performance and the necessary information for proceeding to the next step in the design process, namely, the application of a characteristic-based or other appropriate detailed one-dimensional wave calculation that locates more precisely the proper porting around the periphery of the wave rotor. Examples of the design procedure are given to demonstrate its utility and generality. These examples also illustrate the large gains In performance that might be realized with the use of wave rotor enhanced propulsion cycles.Item Assessment of Combustion Modes for Internal Combustion Wave Rotors(1999-04) Nalim, M. RaziCombustion within the channels of a wave rotor is examined as a means of obtaining pressure gain during heat addition in a gas turbine engine. Three modes of combustion are assessed: premixed autoignition (detonation), premixed deflagration, and non-premixed autoignition. The last two will require strong turbulence for completion of combustion in a reasonable time in the wave rotor. The autoignition modes will require inlet temperatures in excess of 800 K for reliable ignition with most hydrocarbon fuels. Examples of combustion mode selection are presented for two engine applications.Item Design Optimization of Injection Molds with Conformal Cooling for Additive Manufacturing(Office of the Vice Chancellor for Research, 2015-04-17) Wu, Tong; Jahan, Suchana A.; Kumaar, Praveen; Tovar, Andres; El-Mounayri, Hazim; Zhang, Yi; Zhang, Jing; Acheson, Doug; Nalim, M. RaziAbstract This is a framework for optimizing additive manufacturing of plastic injection molds. The proposed system consists of three modules, namely process and material modeling, multi-scale topology optimization, and experimental testing, calibration and validation. Advanced numerical simulation is implemented for a typical die with conformal cooling channels to predict cycle time, part quality and tooling life. A thermo-mechanical topology optimization algorithm is being developed to minimize the die weight and enhance its thermal performance. The technique is implemented for simple shapes for validation before it is applied to dies with conformal cooling in future work. A method for designing a die with porous material which can be produced in additive manufacturing is developed. Also a comprehensive set of systemic design rules are developed and to be integrated with CAD modeling to automate the process of obtaining viable plastic injection dies with conformal cooling channels. Finally, material modeling using simulation as well as design of experiments is underway for obtaining the material properties and their variations.Item Experimental and Numerical investigation of hot-jet ignition with shock effects in a constant-volume combustor(Office of the Vice Chancellor for Research, 2015-04-17) Paik, Kyong-Yup; Khan, Nazmuzzaman; Tarraf Kojok, Ali; Nalim, M. RaziA wave rotor, an array of channels arranged around the axis of a cylindrical drum, can be used as a combustor in gas turbine engines in order to reduce the consumption of the fuel by increasing the fuel efficiency. Since the wave rotor combustor consumes fuel in constant volume channels, the engine system derives benefit from not only high temperature of the combusted gas, but also high pressure by containing the hot gas in the channels. Combustion of gas mixture in one of channels ignited by hot jet penetration under the necessity of rapid ignition accompanies complex non-steady phenomena, such as shock wave propagation, shock-flame interaction, and vortex generation in the channel. Especially, when a shock wave passes through the flame surface, the heat release rate and fuel consumption rate can be suddenly increased by a deformation of the flame surface, which are closely related with the combustion time of the fuel mixture. This research aims to investigate the ignition process, and the shock-flame interaction in a constant volume combustor experimentally and numerically to extract useful information for future wave rotor combustor design. Varıous mixtures of CH4 and H2 with equivalence ratio 1.0 were set as fuel for the main chamber, providing variation in chemical kinetic timescale. The hot gas jet consists of combusted gas mixture of a fuel composed of 50% CH4+ 50% H2 (by volume), burned in the pre-chamber with air at equivalence ratio 1.1. For experimental research, three dynamic pressure transducers were installed on the main chamber to measure the pressure changes caused by shock waves and flame propagation in the main chamber. Time-dependent flame and shock wave images up to 20,000 fps were obtained by a high speed camera, and a Z-type schlieren system. The schlieren technique, an optimum system to capture shock waves in the channel, utilizes light deviation due to flow density gradient, visualizing flows which are invisible to the human eye. In numerical research, adaptive mesh refinement for velocity and temperature, and multi-zone reaction modeling to speed up the kinetics were used to analyze turbulent combustion with minimum computational cost. Advanced post-processing techniques were used to calculate flame surface area, heat release rate, and vorticity deposited on flame surface to understand the flame wrinkling and surface increase. Finally, pressure data in main chamber, flame propagation speed, and the large scale of vortices under different initial conditions obtained from the experimental study were compared to the numerical results under the same conditions in order to suggest reference data for designing future wave rotors.Item Experimental Investigation on the Wave Rotor Constant Volume Combustor(AIAA, 2010-07-25) Matsutomi, Yu; Meyer, Scott; Wijeyakulasuriya, Sameera; Izzy, Zuhair; Nalim, M. Razi; Shimo, Masayoshi; Kowalkowski, Mike; Snyder, Philip; Mechanical Engineering, School of Engineering and TechnologyA wave rotor constant volume combustor was designed and built as a collaborative work of Rolls-Royce, Indiana University-Purdue University Indianapolis (IUPUI), and Purdue University. The experiment was designed to operate at rotational speeds of up to 4,200 rpm with air mass flow rates of approximately 18 lbm per second. Initial tests were conducted at 2,100 rpm with ethylene as fuel. The rig was operated with different fuel injection schemes to investigate operational characteristics of the combustor. Successful combustion and pressure gain were achieved over a range of operating conditions.Item EXPERIMENTAL MEASUREMENTS OF FLAME TRANSFER FUNCTION(Office of the Vice Chancellor for Research, 2012-04-13) Hojatpanah, Roozbeh; Nalim, M. RaziIn order to conform to pollutant-related legislations and minimize NOx emissions, modern household boilers and central heating systems are mov-ing towards premixed combustors. These combustors have been very suc-cessful with regards to emissions along with thermal efficiency. However, there implementation has been associated with acoustical instability prob-lems that are best solved through precise design optimization rather than trial and error experimentation. This poster introduces an experimental setup which is designed to inves-tigate and study, acoustic instability at the flame level. The methodology is an experimental determination of the Flame Transfer Function and compari-son of the experimental data with a theoretical model of the flame-burner. A procedure is designed to diagnose the origins of the combustion instabilities by measurement of the Flame Transfer Function experimentally. The exper-imental setup provides an improved assessment of the acoustic instability problem for industrial applications.Item Experimental Test, Model Validation, and Viability Assessment of a Wave-Rotor Constant-Volume Combustor(AIAA, 2017) Nalim, M. Razi; Snyder, Philip H.; Kowalkowski, Michael; Mechanical Engineering, School of Engineering and TechnologyDesign and testing of a wave-rotor constant-volume combustor achieved stable combustion at near-atmospheric inlet conditions and demonstrated the potential of pressure-gain combustion using a wave rotor. An experiment rig with a motor-driven, room-temperature rotor with large thermal mass operated for short durations within heating limits of extensive in-passage rotating instrumentation. Over 30 successful tests were completed, including a 3 s run amounting to about 2000 individual firing events. Fast deflagrative combustion was observed with varied ethylene fuel distribution in the passages, showing good combustor operability, insensitive to leakage. Remarkably high flame speeds and a net pressure gain were indirectly indicated from measurements. A time-marching, spatially one-dimensional numerical model of gas dynamics and combustion was used for aerothermodynamic design, applying loss models previously calibrated with pressure-exchange nonreacting wave-rotor experiments. Major features and trends of the measured gas dynamic and combustion processes showed good agreement with predictions and validated current design methods. Different fuel distributions were tested to better calibrate ignition and combustion submodels. Simulations illustrate the likely explanations for cases with and without observed ignition, spillage during the filling process, and mixture requirements for consistent torch ignition. The viability of wave rotors for realizing a pressure-gain combustor is discussed.Item Expression and Activities of Matrix Metalloproteinases under Oscillatory Shear in IL-1-Stimulated Synovial Cells(2003) Sun, Hui Bin; Nalim, M. Razi; Yokota, HirokiMatrix metalloproteinases (MMPs) are known to play a critical role in tissue disintegration, and an elevated level of MMPs is observed in synovium and synovial fluid of joints with rheumatoid arthritis. During joint movement, synovial tissue receives various mechanical stimuli, but effects of mechanical challenges on regulation of MMPs in rheumatic synovium are poorly understood. Focusing on cellular responses to oscillatory fluid shear in human synovial cells, we determined the expression of MMP-1 and MMP-13 by polymerase chain reaction and immunoblotting as well as proteolytic activities of total MMPs by a fibril degradation assay and zymography. The results revealed that ~0.5 dyn/cm 2 oscillatory shear at 1 Hz not only reduced an mRNA level and a protein level of MMP-1 and MMP-13, but it also decreased collagenase and gelatinase activities of total MMPs. Furthermore, the induction of the MMP expression and activities by interleukin-1 was suppressed by the oscillatory shear. Interestingly, the oscillatory shear upregulated the mRNA expression of TIMP-1 and TIMP-2. Our results support a potential role of oscillatory shear in regulating expression and activities of MMPs in the presence and the absence of proinflammatory cytokine.Item Faculty and Student Perceptions of Project-Enhanced Learning in Early Engineering Education: Barriers, Benefits, and Breakthroughs(2012) Nalim, M. Razi; Rajagopal, Manikanda K.; Helfenbein, Robert J.The application of problem-based learning (PBL) to undergraduate engineering education has emerged as an area of research interest over the past few decades. A related form of active learning is project-enhanced learning (PEL), intended to support integrative thinking and student motivation. PEL is specifically designed as a supplement to, but not a replacement for, traditional teaching methods in early engineering science courses. Data regarding perceived benefits and barriers to PEL as an intervention for improved student learning were collected from instructors engaged in PEL, and were examined using extended-term mixed-method research design (ETMM). ETMM enables researchers to remain attentive to contextual factors shaping program implementation and to changes in implementation over time. The case study included interviews with faculty, and survey instruments as part of the multiple data-point strategy. Among the findings, instructors adding PEL to their instructional strategies expressed satisfaction with improved student motivation, interaction, and socialization, which may help with student success and retention in engineering. Some instructors expressed concern about losing focus on the challenging analytical course topics, but those who attempted PEL were able to achieve appropriate balance by designing project tasks to align well with the topics and by limiting non-aligned project activity. In some cases, instructors who initially resisted adopting PEL changed to a favorable disposition after interacting with students and faculty who were favorable. However, a small number of instructors responded to the survey with a strong negative view of PEL.