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Wåhlin, Anders
Publications (10 of 23) Show all publications
Mattsson, R., Kupiainen, M., Gren, P., Wåhlin, A., Carlsson, T. & Fureby, C. (2004). Pulsed TV holography and schlieren studies, and large eddy simulations of a turbulent jet diffusion flame (ed.). Paper presented at . Combustion and Flame, 139(1-2), 1-15
Open this publication in new window or tab >>Pulsed TV holography and schlieren studies, and large eddy simulations of a turbulent jet diffusion flame
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2004 (English)In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 139, no 1-2, p. 1-15Article in journal (Refereed) Published
Abstract [en]

In the search for an improved understanding of jet-flame dynamics we here compare predictions from large-eddy simulations (LES) and measurements using schlieren and holographic interferometry of a round turbulent jet diffusion flame. The studies concern a turbulent propane-air (C3H 8-O2/N2) diffusion flame under ambient conditions at a Reynolds number of Re=104. The interferometric measurements were performed with an all-electronic method, pulsed TV holography, using a pulsed laser and a fast charge coupled device (CCD) camera. The LES calculations use the probability density function (PDF) flamelet approach with a beta function as the probability density function, whereas the subgrid turbulence is modeled with a one-equation eddy viscosity model. In order to validate the LES model quantitative comparisons of first-order statistical moments of the velocity were first made with available data for nonreactive jets. The LES model captures the statistics well. The next step in the validation process concerns comparing the jet-flame development between LES and the schlieren and pulsed TV holography data. To this end the results of the LES calculations were used to simulate instantaneous interference patterns using ray tracing. The LES model describes the overall behavior of the flame successfully

National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-11030 (URN)10.1016/j.combustflame.2004.06.005 (DOI)000224718400001 ()2-s2.0-4944240995 (Scopus ID)9ec8deb0-6f76-11db-962b-000ea68e967b (Local ID)9ec8deb0-6f76-11db-962b-000ea68e967b (Archive number)9ec8deb0-6f76-11db-962b-000ea68e967b (OAI)
Note
Validerad; 2004; 20060926 (cira)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mattsson, R., Gren, P. & Wåhlin, A. (2003). Laser ignition of premixed gases studied by pulsed TV holography (ed.). In: (Ed.), Kay Gastinger (Ed.), Speckle metrology 2003: proceedings ; 18 - 20 June 2003, Trondheim, Norway. Paper presented at Speckle Metrology Conference : 18/06/2003 - 20/06/2003 (pp. 285-290). Bellingham, Wash: SPIE - International Society for Optical Engineering
Open this publication in new window or tab >>Laser ignition of premixed gases studied by pulsed TV holography
2003 (English)In: Speckle metrology 2003: proceedings ; 18 - 20 June 2003, Trondheim, Norway / [ed] Kay Gastinger, Bellingham, Wash: SPIE - International Society for Optical Engineering, 2003, p. 285-290Conference paper, Published paper (Refereed)
Abstract [en]

Pulsed TV holography is an all-electronic version of pulsed holographic interferometry. Such a system was used to study ignition of pre-mixed flammable gases. The object was recorded in its undisturbed and disturbed state followed by an evaluation of the changes in refractive index field between those two states. The essential components of the set-up are an injection seeded, twin cavity double pulsed Nd:YAG laser and a CCD camera. A focused laser pulse from the same laser that was used for the recording of the digital hologram initiated the ignition of the pre-mixed gas. Results from the recordings show the ignition process. From the experimental phase maps the refractive index of the gas mixture could be determined. This method makes it possible to determine the proportion of components in a pre-mixed flammable gas in situ

Place, publisher, year, edition, pages
Bellingham, Wash: SPIE - International Society for Optical Engineering, 2003
Series
Proceedings of the Society of Photo-Optical Instrumentation Engineers ; 4933
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-30827 (URN)10.1117/12.516652 (DOI)000184179200046 ()2-s2.0-0242637508 (Scopus ID)4cc14e00-bb56-11db-b560-000ea68e967b (Local ID)0-8194-4728-5 (ISBN)4cc14e00-bb56-11db-b560-000ea68e967b (Archive number)4cc14e00-bb56-11db-b560-000ea68e967b (OAI)
Conference
Speckle Metrology Conference : 18/06/2003 - 20/06/2003
Note
Godkänd; 2003; 20061026 (cira)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Wåhlin, A. & Finnström, M. (2001). Mekanikundervisning i smågrupper (ed.). In: (Ed.), (Ed.), Kvalitetskonferens 2001: . Paper presented at Kvalitet och förbättringsarbete vid universitet och högskolor : 25/09/2001 - 27/09/2001. : Högskoleverket
Open this publication in new window or tab >>Mekanikundervisning i smågrupper
2001 (Swedish)In: Kvalitetskonferens 2001, Högskoleverket , 2001Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Högskoleverket, 2001
National Category
Fluid Mechanics and Acoustics Applied Mechanics
Research subject
Fluid Mechanics; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-40445 (URN)f968ad80-c4f9-11dc-af05-000ea68e967b (Local ID)f968ad80-c4f9-11dc-af05-000ea68e967b (Archive number)f968ad80-c4f9-11dc-af05-000ea68e967b (OAI)
Conference
Kvalitet och förbättringsarbete vid universitet och högskolor : 25/09/2001 - 27/09/2001
Note
Godkänd; 2001; 20080117 (ysko)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Li, X., Gren, P., Wåhlin, A. & Schedin, S. (1999). Pulsed TV holography and tomography for the study of transient waves in air (ed.). Paper presented at . Optics and Laser Technology, 31(1), 23-32
Open this publication in new window or tab >>Pulsed TV holography and tomography for the study of transient waves in air
1999 (English)In: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 31, no 1, p. 23-32Article in journal (Refereed) Published
Abstract [en]

Transient waves in air are recorded and reconstructed using pulsed TV holography and computerized tomography (CT). Experiments are performed with an electrical discharge between two electrodes as the acoustic wave source. The free space wave-fronts and pressure fields are reconstructed. Waves reflected and diffracted by different obstacles are also recorded and reconstructed in three dimensions. Speckle averaging and image processing techniques are used to get the high quality projection fields needed for CT reconstruction.

National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-10998 (URN)10.1016/S0030-3992(99)00031-6 (DOI)000081812800021 ()2-s2.0-0032672090 (Scopus ID)9e46bf60-ff1e-11db-b19d-000ea68e967b (Local ID)9e46bf60-ff1e-11db-b19d-000ea68e967b (Archive number)9e46bf60-ff1e-11db-b19d-000ea68e967b (OAI)
Note
Godkänd; 1999; 20070510 (cira)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Li, X., Gren, P. & Wåhlin, A. (1998). Visualisation of transient waves in air by tomography and pulsed TV holography (ed.). In: (Ed.), (Ed.), International Conference on Optical Methods and Data Processing in Heat and Fluid Flow: 16 - 17 April 1998, City University, London, UK. Paper presented at International Conference on Optical Methods and Data Processing in Heat and Fluid Flow : 16/04/1998 - 17/04/1998. Bury St. Edmunds: Institution of Mechanical Engineers
Open this publication in new window or tab >>Visualisation of transient waves in air by tomography and pulsed TV holography
1998 (English)In: International Conference on Optical Methods and Data Processing in Heat and Fluid Flow: 16 - 17 April 1998, City University, London, UK, Bury St. Edmunds: Institution of Mechanical Engineers, 1998Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Bury St. Edmunds: Institution of Mechanical Engineers, 1998
Series
IMechE conference transactions ; 1998:2
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-35930 (URN)aa94a150-ff9c-11db-b19d-000ea68e967b (Local ID)1-86058-142-0 (ISBN)aa94a150-ff9c-11db-b19d-000ea68e967b (Archive number)aa94a150-ff9c-11db-b19d-000ea68e967b (OAI)
Conference
International Conference on Optical Methods and Data Processing in Heat and Fluid Flow : 16/04/1998 - 17/04/1998
Note
Godkänd; 1998; 20070511 (cira)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Urgela, S. & Wåhlin, A. (1997). Elastic constants of a wooden plates derived from transient bending wave holographic interferograms (ed.). Paper presented at . Wood research, 42(3), 23-36
Open this publication in new window or tab >>Elastic constants of a wooden plates derived from transient bending wave holographic interferograms
1997 (English)In: Wood research, ISSN 1336-4561, Vol. 42, no 3, p. 23-36Article in journal (Refereed) Published
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-13424 (URN)ca608ad0-02d0-11dc-ad0a-000ea68e967b (Local ID)ca608ad0-02d0-11dc-ad0a-000ea68e967b (Archive number)ca608ad0-02d0-11dc-ad0a-000ea68e967b (OAI)
Note
Godkänd; 1997; Bibliografisk uppgift: Tidskriften även med titel: Wood research (proceedings); 20070515 (cira)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Fällström, K.-E., Molin, N.-E., Olofsson, K., Schedin, S. & Wåhlin, A. (1997). Mechanical and thermal effects in a steel plate impacted by a focused laser pulse (ed.). Paper presented at . Nondestructive Testing and Evaluation, 13(5), 293-307
Open this publication in new window or tab >>Mechanical and thermal effects in a steel plate impacted by a focused laser pulse
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1997 (English)In: Nondestructive Testing and Evaluation, ISSN 1058-9759, E-ISSN 1477-2671, Vol. 13, no 5, p. 293-307Article in journal (Refereed) Published
Abstract [en]

A short laser pulse from a 1 J ruby laser is focused at a steel plate. The effect will be that the material surface at the impact point becomes very rapidly heated. Metal vapour leaves the surface at a very high velocity. That is, both a mechanical impulse and local thermal energy are transferred to the plate. The mechanical impulse creates propagating bending waves in the plate, which in turn creates transient sound waves in the surrounding air. The heated spot at the plate surface creates thermal stresses in the plate which give rise to an out-of-plane deformation of the plate. This deformation is added up to the propagating bending waves. These effects are studied in experiments using pulsed holographic interferometry.

National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-11165 (URN)a11f5b90-bb56-11db-b560-000ea68e967b (Local ID)a11f5b90-bb56-11db-b560-000ea68e967b (Archive number)a11f5b90-bb56-11db-b560-000ea68e967b (OAI)
Note
Godkänd; 1997; 20061026 (cira)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Jansson, E., Moral, A., Frydén, L., Niewczyk, B., Molin, N.-E., Runnemalm, A., . . . Wåhlin, A. (1997). On the acoustical function of the violin (ed.). In: (Ed.), 25. Congresso nazionale : Perugia, 21-23 maggio 1997 : atti / Associazione italiana di acustica: . Paper presented at Congresso nazionale (Associazione italiana di acustica) : 21/05/1997 - 23/05/1997.
Open this publication in new window or tab >>On the acoustical function of the violin
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1997 (English)In: 25. Congresso nazionale : Perugia, 21-23 maggio 1997 : atti / Associazione italiana di acustica, 1997Conference paper, Published paper (Refereed)
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-28489 (URN)24e1c070-020c-11dc-ad0a-000ea68e967b (Local ID)24e1c070-020c-11dc-ad0a-000ea68e967b (Archive number)24e1c070-020c-11dc-ad0a-000ea68e967b (OAI)
Conference
Congresso nazionale (Associazione italiana di acustica) : 21/05/1997 - 23/05/1997
Note

Godkänd; 1997; 20070514 (cira)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-02-05Bibliographically approved
Schedin, S., Gren, P. & Wåhlin, A. (1997). Shock waves in an elliptical cavity with varying height (ed.). Paper presented at . Shock Waves, 7(6), 343-350
Open this publication in new window or tab >>Shock waves in an elliptical cavity with varying height
1997 (English)In: Shock Waves, ISSN 0938-1287, E-ISSN 1432-2153, Vol. 7, no 6, p. 343-350Article in journal (Refereed) Published
Abstract [en]

Transient shock waves in a confined elliptical chamber are experimentally investigated. Quantitative results of the pressure distribution are obtained for an air-filled cavity. Lower bounding surfaces of different geometrical shapes can be inserted making it possible to get chambers with varying height. An electrical discharge across a pair of electrodes inside the cavity gives rise to the shock waves. Double pulsed holographic interferometry is used to study the propagation and focusing process of the waves. The results are quantitatively evaluated by using the method of two-reference-beam holography. The angular pressure distribution behind the converging wave front is presented for different geometries of an air-filled cavity. The pressure distribution is non-homogeneous but symmetric along the wave front. The pressure level is higher for the geometry where the height of the chamber decreases with the radial distance from the outgoing focus and lower for increasing height of the chamber. In addition, shock waves in a water-filled cavity are studied. In this case qualitative results are obtained.

National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-9770 (URN)10.1007/s001930050089 (DOI)000071011800004 ()8737f1d0-02bc-11dc-ad0a-000ea68e967b (Local ID)8737f1d0-02bc-11dc-ad0a-000ea68e967b (Archive number)8737f1d0-02bc-11dc-ad0a-000ea68e967b (OAI)
Note
Godkänd; 1997; 20070515 (cira)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Fällström, K.-E., Olofsson, K., Sarady, I. & Wåhlin, A. (1996). Generating and recording transient bending waves in plates by pulsed lasers (ed.). Paper presented at . Experimental techniques (Westport, Conn.), 20(1), 15-19
Open this publication in new window or tab >>Generating and recording transient bending waves in plates by pulsed lasers
1996 (English)In: Experimental techniques (Westport, Conn.), ISSN 0732-8818, E-ISSN 1747-1567, Vol. 20, no 1, p. 15-19Article in journal (Refereed) Published
Abstract [en]

We have presented a method to generate bending waves in a plate by focusing a Q-switched Nd:YAG-laser pulse on its surface. These waves are recorded by double pulsed hologram interferometry. Evaluation of the interferograms show that the bending wave pattern is very similar to what is predicted by the Kirchhoff plate equation assuming a point impact of infinitesimally short duration. This indicates that a short Nd:YAG-laser pulse may be considered as a Dirac pulse in space and time. Future investigations will be performed with a more powerful and "cleaner" laser to get a higher energy and impulse transfer to the plate thus giving bending waves of larger amplitude. Promising preliminary experiments have also begun using a double pulsed ruby laser both for generating and recording of bending waves

National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-3573 (URN)16645fa0-bb56-11db-b560-000ea68e967b (Local ID)16645fa0-bb56-11db-b560-000ea68e967b (Archive number)16645fa0-bb56-11db-b560-000ea68e967b (OAI)
Note
Godkänd; 1996; 20061026 (cira)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
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