The Effect of Scale and Working Fluid on Sweeping Jet Frequency and Oscillation Angle

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Brian T. Bohan ◽  
Marc D. Polanka
Keyword(s):  
High Speed ◽  
Working Fluid ◽  
Performance Parameters ◽  
High Speed Video ◽  
Video Recordings ◽  
Angle Measurements ◽  
Scale Models ◽  
Fluid Properties ◽  
Mass Flowrate ◽  
Parameters Of Interest

Abstract This study was conducted to quantify in a controlled manner the effect of oscillator scale and working fluid on oscillator performance. The performance parameters of interest include the oscillation frequency and oscillation spread angle. Three scale models were manufactured with model attributes identical except for scale with models at two times and three times a baseline scale. Four working fluids were tested including helium, ethylene, carbon dioxide, and propane to generate a range of densities and viscosities. The frequency and oscillation angle measurements were obtained using high-speed video recordings of visible schlieren imagery. Trends in frequency were observed and quantified for each oscillator scale and working gas as a function of mass flowrate. This paper shows that these values could all be nondimensionalized with the data collapsing to a single Strouhal number between 0.015 and 0.018 depending on surface roughness, independent of the Reynolds number. This result expands on the authors' previously published work and confirms the previous finding that reveals the geometry and fluid properties also scale and collapse.

Water skating in the larvae of dixella aestivalis (Diptera) and hydrobius fuscipes (Coleoptera)

1999 ◽  
Vol 202 (7) ◽  
pp. 845-853
Author(s):  
J. Brackenbury
Keyword(s):  
High Speed ◽  
The Body ◽  
Water Interface ◽  
Body Movements ◽  
Chironomid Larvae ◽  
High Speed Video ◽  
Adhesive Organ ◽  
Video Recordings ◽  
Air Water Interface

The kinematics of locomotion was investigated in the aquatic larvae of Dixella aestivalis and Hydrobius fuscipes with the aid of high-speed video recordings. Both insects are able to skate on the surface of the water using the dorso-apical tracheal gill as an adhesive organ or ‘foot’. Progress relies on the variable adhesion of the foot between ‘slide’ and ‘hold’ periods of the locomotory cycle. The flexural body movements underlying skating in D. aestivalis can be derived directly from the figure-of-eight swimming mechanism used in underwater swimming. The latter is shown to be similar to figure-of-eight swimming in chironomid larvae. This study shows how the deployment of a ‘foot’ enables simple side-to-side flexural movements of the body to be converted into effective locomotion at the air-water interface.

scholarly journals Debunking the viper's strike: harmless snakes kill a common assumption

2016 ◽  
Vol 12 (3) ◽  
pp. 20160011 ◽  
Author(s):  
David A. Penning ◽  
Baxter Sawvel ◽  
Brad R. Moon
Keyword(s):  
High Speed ◽  
Past Century ◽  
Loss Of Consciousness ◽  
Common Assumption ◽  
Motor Responses ◽  
High Speed Video ◽  
The Past ◽  
Venomous Snakes ◽  
Video Recordings ◽  
Very High

To survive, organisms must avoid predation and acquire nutrients and energy. Sensory systems must correctly differentiate between potential predators and prey, and elicit behaviours that adjust distances accordingly. For snakes, strikes can serve both purposes. Vipers are thought to have the fastest strikes among snakes. However, strike performance has been measured in very few species, especially non-vipers. We measured defensive strike performance in harmless Texas ratsnakes and two species of vipers, western cottonmouths and western diamond-backed rattlesnakes, using high-speed video recordings. We show that ratsnake strike performance matches or exceeds that of vipers. In contrast with the literature over the past century, vipers do not represent the pinnacle of strike performance in snakes. Both harmless and venomous snakes can strike with very high accelerations that have two key consequences: the accelerations exceed values that can cause loss of consciousness in other animals, such as the accelerations experienced by jet pilots during extreme manoeuvres, and they make the strikes faster than the sensory and motor responses of mammalian prey and predators. Both harmless and venomous snakes can strike faster than the blink of an eye and often reach a target before it can move.

Terrestrial locomotion in the black-billed magpie: kinematic analysis of walking, running and out-of-phase hopping

2000 ◽  
Vol 203 (14) ◽  
pp. 2159-2170 ◽  
Author(s):  
M. Verstappen ◽  
P. Aerts ◽  
R. Van Damme
Keyword(s):  
Kinematic Analysis ◽  
High Speed ◽  
Bird Species ◽  
Pica Pica ◽  
Terrestrial Locomotion ◽  
High Speed Video ◽  
Video Recordings ◽  
Flexion Extension

The inter-limb kinematic patterns of walking, running and out-of-phase hopping in black-billed magpies (Pica pica) were studied using high-speed video recordings. The flexion/extension patterns of the joints were similar between the gait types, suggesting that the within-leg control of the angular excursions is similar. This result is further supported by the fact that running and hopping are alternative gaits at speeds higher than walking; however, magpies show a preference for hopping. Moreover, only small differences occur between the kinematic patterns of the two limbs during out-of-phase hopping, during which the legs are believed to have different functions. The hindlimb kinematic patterns of magpies are like those of other flying and more terrestrial bird species; however, striking differences are found in comparison with humans at the level of the internal angles. This is probably due to the differences in the morphology and configuration of their legs.

EXPLORATORY STUDY ON AIRBAG SUITABILITY FOR LOW ENGINE CAPACITY MOTORCYCLES

2016 ◽  
Vol 78 (4) ◽  
Author(s):  
Aqbal Hafeez Ariffin ◽  
Mohd Syazwan Solah ◽  
Azhar Hamzah ◽  
Mohd Hafzi Md Isa ◽  
Zulhaidi Mohd Jawi ◽  
...  
Keyword(s):  
Exploratory Study ◽  
High Speed ◽  
Side Impact ◽  
Test Results ◽  
Passenger Cars ◽  
High Speed Video ◽  
Video Recordings ◽  
Motorcycle Crashes ◽  
Crash Tests ◽  
Engine Capacity

Motorcyclist constituted more than 50% of road deaths in Malaysia. Statistics showed that most fatal motorcyclist crashes involved passenger cars: with sideswipe or side impact reported to be the most frequent crash configurations. Many related studies have been performed to completely understand such motorcycle crashes which resulted in many safety inventions. These include installation of airbag onto motorcycle to study its effectiveness in potentially reducing motorcyclist’s injury. However, previous related studies known mainly dealt airbag’s effectiveness for large cc motorcycles. Hence, an exploratory study was conducted to study airbag’s suitability in mitigating rider’s injury during collision for motorcycle with low engine capacity (cc). Two different full-scale crash tests of motorcycle (with and without mounted airbag) side-impacting passenger car were conducted in accordance to ISO 13232. The test results in terms of high-speed video recordings (crash kinematics), motorcycle damage profiles and dummy injuries were analysed and discussed. It could be suggested from the results obtained that an airbag system for low cc motorcycle is feasible and further study is needed for better airbag concept and design which could reduce motorcyclist injury during collision.

Characteristics of Swirl Effervescent Atomizer Spray Angle

2014 ◽  
Vol 607 ◽  
pp. 108-111
Author(s):  
Zulkifli Abdul Ghaffar ◽  
Salmiah Kasolang ◽  
Ahmad Hussein Abdul Hamid
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Spray Angle ◽  
Working Fluid ◽  
Intensity Effect ◽  
Video Recordings ◽  
High Speed Video Camera ◽  
Swirl Intensity ◽  
Effervescent Atomizer ◽  
Vane Angle

In the application of sprays produced by an atomizer, spray angle is one of key performance parameters. A larger spray angle is often required in providing a better spray dispersion. Swirl effervescent atomizer is one of the existing atomizers with the capability to produce a large spray angle. The formation of spray angle from this atomizer however is hardly understood. A newly-designed swirl effervescent atomizer was developed and tested with different swirl-generating vane angle in order to understand the swirl intensity effect on the spray angle. Experiments were carried out based on a cold flow test approach using water as the working fluid and nitrogen gas as the atomizing agent. High-speed shadowgraph technique was deployed to record the resultant sprays produced. Video recordings, acquired using a high-speed video camera, were converted to a sequence of images for further analysis using an image processing software. It was found that the spray angle increases with the swirl-generating vane angle. Specifically, the spray angle shows an abrupt increase for the case of swirl-generating vane angle changing from 30° to 45° but visualizes only a gradual increase in the case of swirl-generating vane angle changing from 45° to 60°.

scholarly journals Refrigeration Process With High Speed Technology

1998 ◽  
Author(s):  
Maunu Kuosa ◽  
Jari Backman ◽  
Timo Talonpoika ◽  
Petri Sallinen ◽  
Jaakko Larjola ◽  
...  
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Cooling Capacity ◽  
Working Fluid ◽  
Pascal Program ◽  
Two Stage ◽  
Program Unit ◽  
Fluid Properties ◽  
Industrial Refrigeration ◽  
Process Calculation

The aim of this study was to make a computer program that simulates a standard refrigeration process, and a process provided with a bubble intercooler. A further object of the study was to establish the suitability of a turbocompressor for small refrigeration plants. Firstly the fundamentals of refrigeration machines and industrial refrigeration systems are discussed. An iteration procedure of steady state refrigeration process calculation is introduced. Fluid properties are calculated with the program units created for the modelling of an ORC power plant. Specific input files were made for 6 process fluids R134a, R123, isopentane, isobutane, toluene and ammonia. The compressor program is linked to the refrigeration process simulation program in order to model single stage and two stage radial compressors. The Turbo Pascal program made for microcomputers is modular, which makes it possible to develop and test the program unit by unit. The maximum deviations of fluid properties from those in tables was found to be less than 1 per cent. To simulate tailor-made refrigeration plants, a simple model is required. On nominal loads the program estimates an optimum intermediate pressure for the bubble process and optimum rotational speed for the radial compressor(s). The lowering of the rotational speed by an inverter gives high COP-values on partial loads of the plant. Based on the example calculation, a two stage turbocompressor calculated with isopentane as the working fluid, a cooling capacity of 1200 W seems to be feasible.

Sign in / Sign up

Export Citation Format

Share Document