Experimental Study of Aerodynamics Around Co-Rotating Blades in a Lawn Mower Deck

1999 ◽  
Author(s):  
W. Chon ◽  
P. Tetzlaff ◽  
R. S. Amano ◽  
A. Triscari ◽  
J. Torresin ◽  
...  
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Feeding System ◽  
Velocity Measurements ◽  
Forward Scatter ◽  
Lawn Mower ◽  
High Speed Video ◽  
Computational Fluid Dynamics Cfd ◽  
Blade Model

Abstract A combination of computational and experimental studies was performed on a 1.1m wide side discharge double-spindle lawn mower deck. For the experimental portion of the study air velocities were measured by using a forward-scatter LDV system. Velocity measurements were collected at several different tangential and axial sections inside the deck. In order to simulate the flow in real operating conditions, a grass feeding system was constructed in the laboratory. LDV test data were also validated by the conducting high-speed video taping of the experiments in several different running conditions. In the computational fluid dynamics (CFD) work, 2-D blade shapes at several arbitrary radial sections have been selected for flow computations around the blade model. The 2-D computational results were compared with the experimental results obtained in this study.

scholarly journals Investigation of Flow Behavior around Corotating Blades in a Double-Spindle Lawn Mower Deck

2005 ◽  
Vol 2005 (1) ◽  
pp. 77-89 ◽  
Author(s):  
W. Chon ◽  
R. S. Amano
Keyword(s):  
Flow Pattern ◽  
High Speed ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Video Camera ◽  
Sound Level ◽  
Lawn Mower ◽  
Level Meter

When the airflow patterns inside a lawn mower deck are understood, the deck can be redesigned to be efficient and have an increased cutting ability. To learn more, a combination of computational and experimental studies was performed to investigate the effects of blade and housing designs on a flow pattern inside a1.1mwide corotating double-spindle lawn mower deck with side discharge. For the experimental portion of the study, air velocities inside the deck were measured using a laser Doppler velocimetry (LDV) system. A high-speed video camera was used to observe the flow pattern. Furthermore, noise levels were measured using a sound level meter. For the computational fluid dynamics (CFD) work, several arbitrary radial sections of a two-dimensional blade were selected to study flow computations. A three-dimensional, full deck model was also developed for realistic flow analysis. The computational results were then compared with the experimental results.

Experimental Investigation Into the High Altitude Relight of a Three-Cup Combustor Sector

2018 ◽  
Author(s):  
Michael J. Denton ◽  
Samir B. Tambe ◽  
San-Mou Jeng
Keyword(s):  
Pressure Drop ◽  
High Altitude ◽  
High Speed ◽  
Development Process ◽  
Recirculation Zone ◽  
Operating Conditions ◽  
Pressure Drops ◽  
High Speed Video ◽  
Air Jet ◽  
Flame Development

The altitude relight of a gas turbine combustor is an FAA and EASA regulation which dictates the successful re-ignition of an engine and its proper spool-up after an in-flight shutdown. Combustor pressure loss, ambient pressure, ambient temperature, and equivalence ratio were all studied on a full-scale, 3-cup, single-annular aviation combustor sector to create an ignition map. The flame development process was studied through the implementation of high-speed video. Testing was conducted by placing the sector horizontally upstream of an air jet ejector in a high altitude relight testing facility. Air was maintained at room temperature for varying pressure, and then the cryogenic heat exchanger was fed with liquid nitrogen to chill the air down to a limit of −50 deg F, corresponding with an altitude of 30,000 feet. Fuel was injected at constant equivalence ratios across multiple operating conditions, giving insight into the ignition map of the combustor sector. Results of testing indicated difficulty in achieving ignition at high altitudes for pressure drops greater than 2%, while low pressure drops show adequate performance. Introducing low temperatures to simulate the ambient conditions yielded a worse outcome, with all conditions having poor results except for 1%. High-speed video of the flame development process during the relight conditions across all altitudes yielded a substantial effect of the pressure drop on ignitability of the combustor. An increase in pressure drop was associated with a decrease in the likelihood of ignition success, especially at increasing altitudes. The introduction of the reduced temperature effect exacerbated this effect, further hurting ignition. High velocity regions in the combustor were detrimental to the ignition, and high area, low velocity regions aided greatly. The flame tended to settle into the corner recirculation zone and recirculate back into the center-toroidal recirculation zone (CTRZ), spreading downstream and likewise into adjacent swirl cups. These tests demonstrate the need for new combustor designs to consider adding large recirculation zones for combustor flame stability that will aid in relight requirements.

Experimental Evaluation of Blasting Near Pipelines

2018 ◽  
Author(s):  
Justin Gossard ◽  
Steven A. Waters ◽  
Shane Finneran
Keyword(s):  
High Speed ◽  
Laser Scanning ◽  
Field Experiments ◽  
Separation Distance ◽  
Primary Objective ◽  
Operating Conditions ◽  
Soil Conditions ◽  
Exterior Surface ◽  
High Speed Video ◽  
Test Segment

Construction blasting was proposed as a technique to create a trench for a new pipeline within the right-of-way (ROW) of an existing vintage pipeline where soil conditions consisted primarily of rock. Several field experiments were conducted to assess the potential loading conditions that the vintage pipeline could experience due to various blasting configurations as part of the nearby construction process. Two test pipe segments were constructed from segments removed from the vintage pipeline for use in these experiments. Each test segment contained two vintage bell-bell chill ring girth welds (GW) and were pressurized to operating conditions of the vintage pipeline for the duration of all blasting. Groups of eight resistive strain gages were bonded around the exterior surface of three distinct locations on each test segment. The three locations include one pipe body location and each of the two welds on each segment. Four separate experiments were conducted with each experiment focusing on a unique combination of trench backfill material, compaction level and separation distance from the test pipe segments and the explosive charges. The primary objective throughout these four experiments was to monitor and record the behavior of buried test pipe sections due to nearby blasting activities. Long range 3-dimentional (3D) laser scanning equipment was used to track movement of each test segment from test to test. High-speed video equipment was also employed to capture each blast. The high-speed video provided additional details on the blast energy transfer, verification of individual charge initiation as well as pipeline test segment movement where each pipeline segment was exposed. Peak particle velocity measurements were taken during each test blast. Strain data collected during each test was used to assess potential damage to the vintage pipeline test segments as a result of blasting. The combined information collected from the in-field testing showed that elevated strains and stresses may be observed during blasting activities near pipelines.

Experimental Studies on Dry Gas Seals With Time-Resolved Film Thickness Measurements

2021 ◽  
Author(s):  
Jingjing Luo ◽  
Dieter Brillert
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Theory And Practice ◽  
Experimental Investigations ◽  
Hydrodynamic Effect ◽  
Outer Diameter ◽  
Mechanical Seals ◽  
Gas Seals ◽  
Sealing Gap

Abstract Dry gas lubricated non-contacting mechanical seals (DGS) are acknowledged as the sophisticated shaft end sealing solution which is most commonly found in turbo-compressors. Especially under demanding conditions where high speed is combined with high pressure, DGS becomes the preferred choice over other sealing alternatives. A reliable operation of DGS, due to the non-contact running between its rotating and stationary rings, is secured by the gas film in the region of a few microns in thickness. This paper presents the measurement method of obtaining the thickness of the running gap in two radial positions, namely the inner and outer diameter of the sealing gap, by integrating the proximity sensors in the stationary ring. The experimental investigations concerning film thicknesses, pressure distributions in the gas film and axial vibrations are carried out in an industry DGS up to 50 bar and 10,000 rpm, whereby a good insight into the dynamic behaviour of the sealing gap is provided. The results demonstrate the practicability of obtaining the gas film parameters in a grooved gas seal, bridging the gap between theory and practice. In combination with the experimental work presented in this paper, the numerical model for simulating the seal performance programmed in MATLAB is compared and validated. The comparisons for various operating conditions and groove profiles are discussed with the focus lying on the hydrodynamic effect in the gas film.

Multi-Dimensional CFD Analysis of Rotating Blades in a Lawnmower Deck

2002 ◽  
Author(s):  
P. A. Hagen ◽  
W. Chon ◽  
R. S. Amano
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Flow Patterns ◽  
Cfd Analysis ◽  
Rotating Blades ◽  
Cfd Models ◽  
High Speed Video Camera ◽  
Computational Fluid Dynamics Cfd ◽  
And Behavior ◽  
Blade Model

Aerodynamic experimentation and investigation of rotating blades has pioneered the research necessary for innovative lawnmower design. In this study, Computational Fluid Dynamics (CFD) models are generated for single and triple-blade arrangements to analyze their flow patterns and behavior. For the 2-D CFD analysis, blade profiles at several arbitrary radial sections have been selected for flow computations around the blade model. Likewise, the 3-D CFD analysis effectively simulates the flow patterns inside the entire triple-blade mower deck, as well as in single-blade enclosures. The accuracy of the attained CFD solutions was determined through comparison with experimental data. The flow behaviors were observed using both Laser Doppler Velocimetry (LDV) and a high-speed video camera recording at 2000 frames per second. Strain gage and pressure transducer analysis also aided in the correlative effort. It has been observed that both the mower deck configuration and blade profile share equal significance in the resultant flow profiles.

Modeling and Experimental Investigation of Bubble Formation in Shear-Thinning Liquids

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Mohamad Taghi Esfidani ◽  
Mohammad Reza Oshaghi ◽  
Hossein Afshin ◽  
Bahar Firoozabadi
Keyword(s):  
Power Law ◽  
High Speed ◽  
Gas Flow ◽  
Bubble Formation ◽  
Experimental Studies ◽  
Methyl Cellulose ◽  
Operating Conditions ◽  
Wide Range ◽  
Bubble Sizes ◽  
Newtonian Liquids

This investigation presents both theoretical and experimental studies on the size of a growing bubble in power-law non-Newtonian liquids. At first, some previous works on the prediction of bubble size in Newtonian liquids have been extended by considering the balance of forces acting on the bubble at the moment of separation. Predicted bubble sizes were validated against the experimental results for a wide range of operating conditions, including different gas flow rates and needle diameters as well as a wide range of physical properties of the Newtonian liquids. Furthermore, in order to determine the size of the bubbles formed in power-law non-Newtonian liquids with a similar analysis, the effective shear rate of bubble growth was calculated in which the rheological properties of fluid were taken into account and subsequently the viscosity of the fluid was modified. Theoretically obtained bubble sizes for non-Newtonian liquids are in a good agreement with our experimental high-speed video observations of three carboxyl methyl cellulose (CMC) solutions.

The Effects of Different Support Forms on the Aerodynamic Characteristics of the High-Speed Train Model

2012 ◽  
Vol 246-247 ◽  
pp. 461-465
Author(s):  
Bao Yu Li ◽  
Xi Zhuang Shan ◽  
Zhi Gang Yang
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Aerodynamic Characteristics ◽  
Operating Conditions ◽  
High Speed Train ◽  
Reference Velocity ◽  
Computational Fluid Dynamics Cfd ◽  
Aerodynamic Parameters ◽  
Support Interference ◽  
Good Support

By the method of computational fluid dynamics (CFD), this paper calculates the aerodynamic parameters of one complex high-speed train model which adopts different support forms when the reference velocity is 70m/s under different operating conditions. It also analyses the support interference mechanism from the point of flow field structure. The results show that the distributed cylinder support form causes least interference on the model, while the single big cylinder support forms change the flow field structures much which leads to much change of the aerodynamic parameters of the model. The distributed cylinder support form can be applied as a good support form for the high-speed train wind tunnel tests.

scholarly journals DETERMINATION OF DYNAMIC LOADS IN TRANSMISSIONS TRACKED FOREST MACHINE WHILE OVERCOMING OBSTACLES

2017 ◽  
Vol 7 (1) ◽  
pp. 185-196
Author(s):  
Клубничкин ◽  
Vladislav Klubnichkin ◽  
Клубничкин ◽  
Evgeniy Klubnichkin ◽  
Бухтояров ◽  
...  
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Dynamic Loads ◽  
Pilot Studies ◽  
Torque Transmission ◽  
Characteristic Species ◽  
Final Drive

The theoretical analysis of dynamic phenomena in transmission tracked forest machine is much more difficult in the absence of experimental data on the effects of the input characteristic of the machine. The most characteristic species in the transmission effects that arise under real operating conditions allow to evaluate the results of experimental studies, they also provide an opportunity to assess the quality of theoretical studies. To determine the loading of the transmission in the experiment involves the measurement of a number of kinematic and power parameters characterizing the speed and stress state of the transmission. In the course of the research used a special measuring equipment made in Germany includes the high-speed digital telemetry system for strain "TEL1-PCM-HS" company KMT. This article describes how to determine the dynamic load transmission elements tracked forest machine LZ-5 in overcoming individual barriers in experimental studies (tests). The paper presents a program of pilot studies tracked forest machine. Presented curves change the time settings on the final drives and cardan shaft, depending on the speed of the engine and drive sprockets in overcoming obstacles GLZM with different gears. histograms were constructed on the distribution of the torque transmission shafts for various modes of overcoming obstacles in order to analyze the influence of operational factors on the magnitude of dynamic loads. The article presents the distribution curve of the moments on the driven shaft final drive to overcome obstacles tracked forest machine with a pack assortments in the volume of 12m3. It was noted that there are no less than 20 times the dynamic point values, which exceed the estimated time for the overcoming of obstacles. From the studies that the transmission level of at least dynamic forces having height obstacles.

Numerical and Experimental Studies of Collapsing Cavitation Bubbles for Ballast Water Treatment

2018 ◽  
Author(s):  
Chang-Wei Kang ◽  
Tandiono Tandiono ◽  
Xin Lu ◽  
Cary K. Turangan ◽  
Hafiiz Osman ◽  
...  
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Hydrodynamic Cavitation ◽  
High Speed Photography ◽  
Gas Bubble ◽  
Liquid Pressure ◽  
Cfd Simulations ◽  
Bubble Cloud ◽  
Computational Fluid Dynamics Cfd ◽  
Sudden Jump

In this paper, we report both experimental and computational studies of hydrodynamic cavitation generated by accelerating liquid through a series of constrictions. The detailed process of cavitation generation is visualized using a high-speed photography. The cavitation is initiated when a gas bubble moves towards the constrictions. The gas bubble initially accelerates, expands and then splits into smaller bubbles when it moves along the constriction. As these bubbles migrate into a large liquid compartment, they collapse violently to form a bubble cloud, owing to a sudden jump in liquid pressure in the compartment. The experimental observation is further confirmed using computational fluid dynamics (CFD) simulations. We also present experimental evidence showing a significant reduction in gram-negative Escherichia coli concentration after it passes through the constrictions.

scholarly journals A Parallel CFD Tool to Produce Faulty Blade Signatures for Diagnostic Purposes

1998 ◽  
Author(s):  
D. G. Koubogiannis ◽  
V. P. Iliadis ◽  
K. C. Giannakoglou
Keyword(s):  
High Speed ◽  
Unstructured Grids ◽  
Fast Response ◽  
Operating Conditions ◽  
Pressure Measurements ◽  
Diagnostic Systems ◽  
Compressor Cascade ◽  
Computational Fluid Dynamics Cfd ◽  
Response Pressure ◽  
The One

In the turbomachinery field, many diagnostic systems utilize databases with symptoms corresponding to the most frequent operation faults. Thanks to Computational Fluid Dynamics (CFD), databases can be created without costly experiments, whereas the use of unstructured grids in combination with parallel processing makes the whole task easy and fast to accomplish. In this paper, a procedure that builds up a database for gas-turbine fault diagnosis is demonstrated. Advanced CFD tools that operate concurrently on multi-processor platforms are used. The so-prepared database contributes to the identification of faults through the analysis of the unsteady pressure signals that correspond to hypothetical sensors located in the inter-blade region. The pressure signals are post-processed in a similar way to the one experimentalists employ for fast-response pressure measurements. Symptoms related to displaced and/or twisted blades in an industrial high-speed compressor cascade, at design and off-design operating conditions, are analyzed.

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