Development of cost-effective shock tube based on experimental and numerical analysis

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Praveenkumar Thaloor Ramesh ◽  
Vijayaraja Kengaiah ◽  
Endalkachew Mosisa Gutema ◽  
Prabu Velusamy ◽  
Dhivya Balamoorthy
Keyword(s):  
Shock Tube ◽  
High Speed ◽  
Cost Effective ◽  
Project Work ◽  
Experimental Investigations ◽  
Content Type ◽  
Pressure Transducers ◽  
Speed Flow ◽  
Aerodynamic Test ◽  
Aerodynamic Parameters

Purpose The purpose of the study is to design economical shock tube. It is an instrument used for experimental investigations not only related to shock phenomena but also for the behavior of the material when it is subjected to high-speed flow. The material used here in this shock tube is stainless steel ss304 and aluminum. A shock tube consists of two sections, namely, the driver and the driven. The gas in the driven and driver is filled with atmospheric air and nitrogen, respectively, under the predominant condition. Design/methodology/approach The focus of the study is on the design and fabrication of shock tubes. a shock tube is a research tool to make an aerodynamic test in the presence of high pressure and temperature by generating moving normal shock waves under controlled conditions. Findings The main necessity for instrumentation in the shock tube experiment is to know the velocity of the moving shock wave from which the other parameters can be calculated. the pressure transducers are located in the shock tube in various locations to measure aerodynamic parameters in terms of pressure. Originality/value The main objective of this project work is to make an experimental setup to produce supersonic velocity with the readily available material in the market in a highly safe manner.

Cavitation erosion behavior of hydraulic concrete under high-speed flow

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xin Wang ◽  
Ting-Qiang Xie
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Cavitation Erosion ◽  
Concrete Strength ◽  
Bubble Collapse ◽  
High Speed Flow ◽  
Content Type ◽  
Erosion Behavior ◽  
Hydraulic Concrete ◽  
Speed Flow

Purpose Cavitation erosion has always been a common technical problem in a hydraulic discharging structure. This paper aims to investigate the cavitation erosion behavior of hydraulic concrete under high-speed flow. Design/methodology/approach A high-speed and high-pressure venturi cavitation erosion generator was used to simulate the strong cavitation. The characteristics of hydrodynamic loads of cavitation bubble collapse zone, the failure characteristics and the erosion development process of concrete were investigated. The main influencing factors of cavitation erosion were discussed. Findings The collapse of the cavitation bubble group produced a high frequency, continuous and unsteady pulse load on the wall of concrete, which was more likely to cause fatigue failure of concrete materials. The cavitation action position and the main frequency of impact load were greatly affected by the downstream pressure. A power exponential relationship between cavitation load, cavitation erosion and flow speed was observed. With the increase of concrete strength, the degree of damage of cavitation erosion was approximately linearly reduced. Originality/value After cavitation erosion, a skeleton structure was formed by the accumulation of granular particles, and the relatively independent bulk structure of the surface differed from the flake structure formed after abrasion.

The Effects of Inlet Boundary Layer Condition and Periodically Incoming Wakes on Secondary Flow in a Low Pressure Turbine Cascade

2020 ◽  
Author(s):  
Tobias Schubert ◽  
Silvio Chemnitz ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
Secondary Flow ◽  
High Speed ◽  
Low Pressure ◽  
Experimental Investigations ◽  
Turbine Cascade ◽  
Flow Conditions ◽  
Low Pressure Turbine ◽  
Speed Flow ◽  
Unsteady Inflow

Abstract A particular turbine cascade design is presented with the goal of providing a basis for high quality investigations of endwall flow at high-speed flow conditions and unsteady inflow. The key feature of the design is an integrated two-part flat plate serving as a cascade endwall at part-span, which enables a variation of the inlet endwall boundary layer conditions. The new design is applied to the T106A low pressure turbine cascade for endwall flow investigations in the High-Speed Cascade Wind Tunnel of the Institute of Jet Propulsion at the Bundeswehr University Munich. Measurements are conducted at realistic flow conditions (M2th = 0.59, Re2th = 2·105) in three cases of different endwall boundary layer conditions with and without periodically incoming wakes. The endwall boundary layer is characterized by 1D-CTA measurements upstream of the blade passage. Secondary flow is evaluated by Five-hole-probe measurements in the turbine exit flow. A strong similarity is found between the time-averaged effects of unsteady inflow conditions and the effects of changing inlet endwall boundary layer conditions regarding the attenuation of secondary flow. Furthermore, the experimental investigations show, that all design goals for the improved T106A cascade are met.

Leveraging NVMe SSDs for Building a Fast, Cost-effective, LSM-tree-based KV Store

2021 ◽  
Vol 17 (4) ◽  
pp. 1-29
Author(s):  
Cheng Li ◽  
Hao Chen ◽  
Chaoyi Ruan ◽  
Xiaosong Ma ◽  
Yinlong Xu
Keyword(s):  
High Speed ◽  
Scale Up ◽  
Cost Effective ◽  
Data Migration ◽  
Solid State Drives ◽  
Content Type ◽  
Memory Processing ◽  
Recent Emergence ◽  
Non Volatile Memory ◽  
High Bandwidth

Key-value (KV) stores support many crucial applications and services. They perform fast in-memory processing but are still often limited by I/O performance. The recent emergence of high-speed commodity non-volatile memory express solid-state drives (NVMe SSDs) has propelled new KV system designs that take advantage of their ultra-low latency and high bandwidth. Meanwhile, to switch to entirely new data layouts and scale up entire databases to high-end SSDs requires considerable investment. As a compromise, we propose SpanDB, an LSM-tree-based KV store that adapts the popular RocksDB system to utilize selective deployment of high-speed SSDs . SpanDB allows users to host the bulk of their data on cheaper and larger SSDs (and even hard disc drives with certain workloads), while relocating write-ahead logs (WAL) and the top levels of the LSM-tree to a much smaller and faster NVMe SSD. To better utilize this fast disk, SpanDB provides high-speed, parallel WAL writes via SPDK, and enables asynchronous request processing to mitigate inter-thread synchronization overhead and work efficiently with polling-based I/O. To ease the live data migration between fast and slow disks, we introduce TopFS, a stripped-down file system providing familiar file interface wrappers on top of SPDK I/O. Our evaluation shows that SpanDB simultaneously improves RocksDB's throughput by up to 8.8 \times and reduces its latency by 9.5–58.3%. Compared with KVell, a system designed for high-end SSDs, SpanDB achieves 96–140% of its throughput, with a 2.3–21.6 \times lower latency, at a cheaper storage configuration.

Simulations of flame propagation during the ignition process in an annular multiple-injector combustor

2019 ◽  
Vol 29 (6) ◽  
pp. 1947-1964 ◽  
Author(s):  
Dongmei Zhao ◽  
Yifan Xia ◽  
Haiwen Ge ◽  
Qizhao Lin ◽  
Jianfeng Zou ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Adaptive Mesh Refinement ◽  
High Speed ◽  
Early Stage ◽  
Adaptive Mesh ◽  
Critical Issue ◽  
Experimental Investigations ◽  
Ignition Process ◽  
High Speed Imaging ◽  
Content Type

Purpose Ignition process is a critical issue in combustion systems. It is particularly important for reliability and safety prospects of aero-engine. This paper aims to numerically investigate the burner-to-burner propagation during ignition process in a full annular multiple-injector combustor and then validate it by comparing with experimental results. Design/methodology/approach The annular multiple-injector experimental setup features 16 swirling injectors and two quartz tubes providing optical accesses to high-speed imaging of flames. A Reynolds averaged Navier–Stokes model, adaptive mesh refinement (AMR) and complete San Diego chemistry are used to predict the ignition process. Findings The ignition process shows an overall agreement with experiment. The integrated heat release rate of simulation and the integrated light intensity of experiment is also within reasonable agreement. The flow structure and flame propagation dynamics are carefully analyzed. It is found that the flame fronts propagate symmetrically at an early stage and asymmetrically near merging stage. The flame speed slows down before flame merging. Overall, the numerical results show that the present numerical model can reliably predict the flame propagation during the ignition process. Originality/value The dedicated AMR method together with detailed chemistry is used for predicting the unsteady ignition procedure in a laboratory-scale annular combustor for the first time. The validation shows satisfying agreements with the experimental investigations. Some details of flow structures are revealed to explain the characteristics of unsteady flame propagations.

The Effects of Inlet Boundary Layer Condition and Periodically Incoming Wakes on Secondary Flow in a Low Pressure Turbine Cascade

2021 ◽  
pp. 1-12
Author(s):  
Tobias Schubert ◽  
Silvio Chemnitz ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
Secondary Flow ◽  
High Speed ◽  
Low Pressure ◽  
Experimental Investigations ◽  
Turbine Cascade ◽  
Flow Conditions ◽  
Low Pressure Turbine ◽  
Speed Flow ◽  
Unsteady Inflow

Abstract A particular turbine cascade design is presented with the goal of providing a basis for high quality investigations of endwall flow at high-speed flow conditions and unsteady inflow. The key feature of the design is an integrated two-part flat plate serving as a cascade endwall at part-span, which enables a variation of the inlet endwall boundary layer conditions. The new design is applied to the T106A low pressure turbine cascade for endwall flow investigations in the High-Speed Cascade Wind Tunnel of the Institute of Jet Propulsion at the Bundeswehr University Munich. Measurements are conducted at realistic flow conditions (M2th = 0.59, Re2th = 200 000) in three cases of different endwall boundary layer conditions with and without periodically incoming wakes. The endwall boundary layer is characterized by 1DCTA measurements upstream of the blade passage. Secondary flow is evaluated by Five-hole-probemeasurements in the turbine exit flow. A strong similarity is found between the time-averaged effects of unsteady inflow conditions and the effects of changing inlet endwall boundary layer conditions regarding the attenuation of secondary flow. Furthermore, the experimental investigations show, that all design goals for the improved T106A cascade are met.

Significant Head Accelerations Can Influence Immediate Neurological Impairments in a Murine Model of Blast-Induced Traumatic Brain Injury

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
David M. Gullotti ◽  
Matthew Beamer ◽  
Matthew B. Panzer ◽  
Yung Chia Chen ◽  
Tapan P. Patel ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Shock Tube ◽  
High Speed ◽  
Biochemical Characterization ◽  
Chronic Traumatic Encephalopathy ◽  
Military Population ◽  
Pressure Transducers ◽  
Blast Overpressure ◽  
Blast Neurotrauma

Although blast-induced traumatic brain injury (bTBI) is well recognized for its significance in the military population, the unique mechanisms of primary bTBI remain undefined. Animate models of primary bTBI are critical for determining these potentially unique mechanisms, but the biomechanical characteristics of many bTBI models are poorly understood. In this study, we examine some common shock tube configurations used to study blast-induced brain injury in the laboratory and define the optimal configuration to minimize the effect of torso overpressure and blast-induced head accelerations. Pressure transducers indicated that a customized animal holder successfully reduced peak torso overpressures to safe levels across all tested configurations. However, high speed video imaging acquired during the blast showed significant head accelerations occurred when animals were oriented perpendicular to the shock tube axis. These findings of complex head motions during blast are similar to previous reports [Goldstein et al., 2012, “Chronic Traumatic Encephalopathy in Blast-Exposed Military Veterans and a Blast Neurotrauma Mouse Model,” Sci. Transl. Med., 4(134), 134ra160; Sundaramurthy et al., 2012, “Blast-Induced Biomechanical Loading of the Rat: An Experimental and Anatomically Accurate Computational Blast Injury Model,” J. Neurotrauma, 29(13), pp. 2352–2364; Svetlov et al., 2010, “Morphologic and Biochemical Characterization of Brain Injury in a Model of Controlled Blast Overpressure Exposure,” J. Trauma, 69(4), pp. 795–804]. Under the same blast input conditions, minimizing head acceleration led to a corresponding elimination of righting time deficits. However, we could still achieve righting time deficits under minimal acceleration conditions by significantly increasing the peak blast overpressure. Together, these data show the importance of characterizing the effect of blast overpressure on head kinematics, with the goal of producing models focused on understanding the effects of blast overpressure on the brain without the complicating factor of superimposed head accelerations.

scholarly journals Velocity Measurements of an Intermittent High-Speed Flow Inside a Micro Shock Tube

2006 ◽  
Vol 72 (713) ◽  
pp. 61-68 ◽  
Author(s):  
Mikiya ARAKI ◽  
Masaaki ARAI ◽  
Koji OKAMOTO ◽  
Tsuneaki ISHIMA ◽  
Tomio OBOKATA
Keyword(s):  
Shock Tube ◽  
High Speed ◽  
Velocity Measurements ◽  
High Speed Flow ◽  
Speed Flow
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