Sharif Digital Repository

This paper is concentrated on soot formation in a JP combustor and it studies the emission in its exhaust gases when the combustor is equipped with different types of exhaust swirler. So, to approve the developed solver, it is required to predict one related flame structure accurately right at the first step. In this regard, we solve a well-documented benchmark test case with available data from experiment. These data are then compared with the current numerical results to evaluate the discrepancies. The comparison indicates that there is good agreement between them. Afterwards, we equip a similar combustor with different types of swirler, simulate the new designed combustor configurations,... 

This paper is concentrated on soot formation in a JP combustor and it studies the emission in its exhaust gases when the combustor is equipped with different types of exhaust swirler. So, to approve the developed solver, it is required to predict one related flame structure accurately right at the first step. In this regard, we solve a well-documented benchmark test case with available data from experiment. These data are then compared with the current numerical results to evaluate the discrepancies. The comparison indicates that there is good agreement between them. Afterwards, we equip a similar combustor with different types of swirler, simulate the new designed combustor configurations,... 

In this work, we attempted to develop an Implicit Coupled Density-Based (ICDB) solver using LU-SGS algorithm based on the AUSM+ up scheme in OpenFOAM. Then sonicFoam solver was modified to include viscous dissipation in order to improve its capability to capture shock wave and aerothermal variables. The details of the ICDB solver as well as key implementation details of the viscous dissipation to energy equation were introduced. Finally, two benchmark tests of hypersonic airflow over a flat plate and a 2-D cylinder were simulated to show the accuracy of ICDB solver. To verify and validate the ICDB solver, the obtained results were compared with other published experimental data. It was... 

In this work, we numerically study the effect of a mini-scale primary-air injector on the formation of soot nano-particles in a model tubular-type gas-turbine combustor fed with JP, i.e. gaseous JP-1. We solve a documented experimental (benchmark) test case to evaluate our numerical solution and compare the achieved flame structure with that of the measured and reported data. The obtained numerical results show good agreements with the experimental data. After ensuring the validity of numerical tool, we install a mini-scale injector, split the incoming air-flow between the primary and secondary streams, inject the primary air into the combustor via the mini-scale injector, and compare the... 

Peridynamics is a nonlocal reformulation of solid mechanics which can reproduce the solution of classical continuum mechanics as its horizon approaches zero. Taking this idea into consideration, we proposed a new coupling approach between meshfree peridynamics and finite element method. An intermediate variable horizon element called “morakkab” is introduced to transfer force and momentum between peridynamic and FEM regions. In the original peridynamic formulation, artificial ghost forces will arise if the horizon varies with position; The creation of these artifacts is avoided by utilizing a modified peridynamic equation of motion based on the concept of co-family. The accuracy of the... 

How can we optimally trade extra computing power to reduce the communication load in distributed computing? We answer this question by characterizing a fundamental tradeoff between computation and communication in distributed computing, i.e., the two are inversely proportional to each other. More specifically, a general distributed computing framework, motivated by commonly used structures like MapReduce, is considered, where the overall computation is decomposed into computing a set of “Map” and “Reduce” functions distributedly across multiple computing nodes. A coded scheme, named “Coded Distributed Computing” (CDC), is proposed to demonstrate that increasing the computation load of the... 

How can we optimally trade extra computing power to reduce the communication load in distributed computing? We answer this question by characterizing a fundamental tradeoff between computation and communication in distributed computing, i.e., the two are inversely proportional to each other. More specifically, a general distributed computing framework, motivated by commonly used structures like MapReduce, is considered, where the overall computation is decomposed into computing a set of “Map” and “Reduce” functions distributedly across multiple computing nodes. A coded scheme, named “coded distributed computing” (CDC), is proposed to demonstrate that increasing the computation load of the... 

Recent developments in Non-Volatile Memories (NVMs) have introduced them as an alternative for SRAMs in on-chip caches. Besides the promising features of NVMs, e.g., near-zero leakage power, immunity to radiation-induced particle strike, and higher density, a major drawback of NVM-based caches is their short lifetime due to limited write endurance. This paper first reveals that in L1 caches, the lifetime of data-cache (D-cache) is about 472x shorter than that of instruction-cache (I-cache) due to extreme imbalance write stress between the two. Then, we propose a technique, so-called Alternating Cache Allocation to Conduct Higher Endurance (A-CACHE), to improve the lifetime of...