Shadowgraph and Schlieren Techniques

Braeuer, Andreas

doi:10.1016/b978-0-444-63422-1.00004-3

Cited by 8 publications

(6 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Some other methods have been used in previous studies to achieve similar purpose, like the particle imaging velocimetry (PIV) [12,14] and using smoker subjects to visualize their breaths [13]. Schlieren imaging relies only on density differences to refract the light beam to visualize an airflow [44]. Human exhaled flow differs from the surrounding air in density, especially when air is immediately expelled from the mouth or nose [17,45].…”

Section: Introductionmentioning

confidence: 99%

Human exhalation characterization with the aid of schlieren imaging technique

Nielsen

Liu

et al. 2017

Building and Environment

109

View full text Add to dashboard Cite

a b s t r a c tThe purpose of this paper is to determine the dispersion and distribution characteristics of exhaled airflow for accurate prediction of disease transmission. The development of airflow dynamics of human exhalation was characterized using nonhazardous schlieren photography technique, providing a visualization and quantification of turbulent exhaled airflow from 18 healthy human subjects whilst standing and lying. The flow shape of each breathing pattern was characterized by two angles and averaged values of 18 subjects. Two exhaled air velocities, u m and u p , were measured and compared. The mean peak centerline velocity, u m was found to decay correspondingly with increasing horizontal distance x in a form of power function. The mean propagation velocity, u p was found to correlate with physiological parameters of human subjects. This was always lower than u m at the mouth/nose opening, due to a vortex like airflow in front of a single exhalation cycle. When examining the talking and breathing process between two persons, the potential infectious risk was found to depend on their breathing patterns and spatial distribution of their exhaled air. Our study when combined with information on generation and distributions of pathogens could provide a prediction method and control strategy to minimize infection risk between persons in indoor environments.

show abstract

Section: Introductionmentioning

confidence: 99%

Human exhalation characterization with the aid of schlieren imaging technique

Nielsen

Liu

et al. 2017

Building and Environment

109

View full text Add to dashboard Cite

show abstract

“…Schlieren imaging relies on thermal differences in the air to refract a light beam to visualize airflows. 16 Refraction due to inhomogeneity in air is made visible by a single-mirror Schlieren optics setup. No invasive or potentially irritant tracers are necessary, and human volunteers are required only to stand in front of a concave mirror and breathe (or talk, cough, and sneeze) across the illuminating light beam that is directed at the center of the mirror, to produce a real-time, visible image of their exhaled airflows and thermal plume.…”

Section: Discussionmentioning

confidence: 99%

“…If there is a change in the refractive index of the air in the test area, the image of the point light source will be deflected slightly. 16 If it is deflected past the edge of the light block, the additional light that enters the camera will appear as streaks of light originating from the area where there was a change in the index of refraction; this is the Schlieren effect. For this study, human volunteers attending the ophthalmology clinic and OR at Raghudeep Eye Hospital, India, between August 25 and 29, 2020, were included in the study.…”

Section: Schlieren Imaging Setup-how Does It Workmentioning

confidence: 99%

Real-time imaging of airflow patterns and impact of infection control measures in ophthalmic practice: a pandemic perspective

Srivastava¹,

Vasavada²,

Vasavada³

et al. 2021

J Cataract Refract Surg

View full text Add to dashboard Cite

show abstract

“…Oleh sebab itu, peneliti tertarik melakukan penelitian mengenai pengaruh bentuk turncated nozzle sudut luar dengan variasi lip thickness dengan harapan dapat diketahui prubahan luasan kestabilan api dan temperatur api. Visualisasi direct photograph dan shadow photograph akan menunjukkan gambaran nyata nyala api [12,13]. Untuk menunjang dan mempertegas hasil penelitian, selain menggunakan metode eksperimen dilakukan juga simulasi numerik (Finite Volume Method) [14,15,16].…”

Section: Pendahuluanunclassified

Pengaruh Lip Thickness Turncated Nozzle Sudut Luar terhadap Karakteristik Api Difusi Concentric Jet Flow

Huda

Widodo

Siswanto

2019

JRM

View full text Add to dashboard Cite

Diffusion combustion is a daily combustion process where is often used primarily in industrial systems. An optimal burner design is needed to get more efficient combustion results. Then the shape of the burner nozzle greatly affects the turbulence between the fuel and air which forms the flow recirculation zone. The flow recirculation zone functions to produce homogeneous mixing and get a more perfect combustion. Recirculation zones are formed to disrupt flow rates, causing vortices and backflow around the end of nozzle. This research uses burner concentric jet flow. The lip thickness of the outer angles turncated nozzle are used 16 mm, 12 mm, 8 mm, 4 mm, and 0 mm length variation To obtain flame stability, the lift off and blow off limits are used with variations in air velocity. Thermocouples are used to measure the flame temperature distribution. The numerical simulations are used to reinforce this study. The results showed that the characteristics of the concentric jet flow diffusion affected by the use of the lip thickness of the outer angles turncated nozzle. The highest concentric jet flow diffusion stability is at 16 mm nozzle. The highest concentric jet flow diffusion temperature is at 12 mm nozzle. Experimental and numerical simulations show the perfect combustion on the 12 mm lip thickness nozzle. This can be seen by direct photographs of blue-dominated flames and the visualization of the temperature contour distribution which is dominated by red.

show abstract

Shadowgraph and Schlieren Techniques

Cited by 8 publications

References 61 publications

Human exhalation characterization with the aid of schlieren imaging technique

Human exhalation characterization with the aid of schlieren imaging technique

Real-time imaging of airflow patterns and impact of infection control measures in ophthalmic practice: a pandemic perspective

Pengaruh Lip Thickness Turncated Nozzle Sudut Luar terhadap Karakteristik Api Difusi Concentric Jet Flow

Contact Info

Product

Resources

About