TY - JOUR AU - Papp, Bálint AU - Istók, Balázs AU - Koren, Márton AU - Balczó, Márton AU - Kristóf, Gergely TI - Statistical assessment of the concentration fluctuations in street canyons via time-resolved wind tunnel experiments JF - JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS J2 - J WIND ENG IND AEROD VL - 246 PY - 2024 PG - 17 SN - 0167-6105 DO - 10.1016/j.jweia.2024.105665 UR - https://m2.mtmt.hu/api/publication/34742505 ID - 34742505 N1 - Export Date: 18 March 2024 Correspondence Address: Papp, B.; Department of Fluid Mechanics, Műegyetem rkp. 3, Hungary; email: papp.balint@gpk.bme.hu Funding details: European Commission, EC, VEKOP-2.3.3-15-2017-00017 Funding details: Gedeon Richter, PD 127919 Funding details: Richter Gedeon Talentum Alapítvány Funding details: Nemzeti Kutatási, Fejlesztési és Innovaciós Alap, NKFIA Funding details: Innovációs és Technológiai Minisztérium, ÚNKP-21-3-I-BME-252 Funding details: National Research, Development and Innovation Office, TKP-6-6 Funding text 1: The present study was funded by grant no. K 124439 from the National Research, Development, and Innovation Office, Hungary. Project no. TKP-6-6/PALY-2021 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021-NVA funding scheme. Bálint Papp's contribution to this paper was supported by the ÚNKP-21-3 New National Excellence Program of the Ministry for Innovation and Technology (Grant No. ÚNKP-21-3-I-BME-252), as well as by the Gedeon Richter Talent Foundation (registered office: Gyömrői út 19–21, 1103 Budapest, Hungary), established by Gedeon Richter Plc. within the framework of the Gedeon Richter PhD Scholarship. Márton Balczó gratefully acknowledges the support of project PD 127919 of the National Research, Development, and Innovation (NRDI) Fund, entitled “Application and validation of measurement techniques related to the physical modeling of the atmospheric boundary layer in a new boundary layer wind tunnel”. The authors wish to acknowledge the support of the European Union and of the Hungarian Government in the project VEKOP-2.3.3-15-2017-00017 "Establishment of a Laboratory for Atmospheric Flows". Funding text 2: The present study was funded by grant no. K 124439 from the National Research, Development, and Innovation Office, Hungary . Project no. TKP-6-6/PALY-202 1 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021-NVA funding scheme. Bálint Papp's contribution to this paper was supported by the ÚNKP-21-3 New National Excellence Program of the Ministry for Innovation and Technology (Grant No. ÚNKP-21-3-I-BME-252 ), as well as by the Gedeon Richter Talent Foundation (registered office: Gyömrői út 19–21, 1103 Budapest, Hungary), established by Gedeon Richter Plc., within the framework of the Gedeon Richter PhD Scholarship. Márton Balczó gratefully acknowledges the support of project PD 127919 of the National Research, Development, and Innovation (NRDI) Fund , entitled “Application and validation of measurement techniques related to the physical modeling of the atmospheric boundary layer in a new boundary layer wind tunnel”. The authors wish to acknowledge the support of the European Union and of the Hungarian Government in the project VEKOP-2.3.3-15-2017-00017 "Establishment of a Laboratory for Atmospheric Flows". AB - Time-resolved wind tunnel experiments are performed for three periodic street canyon configurations: one of uniform (H/W = 1) and two of variable building height (consisting of 0.5H and 1.5H tall towers in aligned and staggered arrangements) for perpendicular wind direction. The velocity field is mapped using Laser Doppler Anemometry (LDA), and the tracer gas concentration is sampled using Fast Flame Ionization Detection (FFID). The concentration field is characterized by the mean concentration and the characteristic percentiles of the concentration-time series, such as the median and the peak, represented by the 99th percentile, in a total of 1138 sampling points. The probability distribution of the concentration in each point is modeled using the gamma distribution, which is fitted based on the mean and the variance of the measured time series. The results show that the mean pedestrian exposure to air pollutants is significantly lower in the case of heterogeneous roof height, although the mean concentration at the leeward corner of the source canyon can locally exceed those of the uniform street canyons for both tower arrangements of variable building height. Moreover, it is shown that the concentration peaks for both tower configurations can significantly exceed those of the uniform canyons case, especially near the sources. © 2024 The Authors LA - English DB - MTMT ER - TY - JOUR AU - Shahzad, Hasan AU - Wang, Xinhua AU - Rasool, Ghulam AU - Lelkes, János AU - Majeed, Afraz Hussain AU - Li, Zhiyong AU - Raizah, Zehba TI - Entropy generation and advanced hydrothermal examination of ferrofluid confined within an irregular cavity under Lorentz forces JF - JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS J2 - J MAGN MAGN MATER VL - 593 PY - 2024 PG - 12 SN - 0304-8853 DO - 10.1016/j.jmmm.2024.171814 UR - https://m2.mtmt.hu/api/publication/34682341 ID - 34682341 N1 - Faculty of Energy and Power Engineering, School of Chemical Engineering and Energy Technology, Dongguan University of Technology, China College of Mechanical and Energy Engineering, Beijing University of Technology, China Department of Mechanical Engineering, Lebanese American University, Beirut, Lebanon Department of Fluid Mechanics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Budapest, Hungary Department of Mathematics, Air University, PAF Complex E-9, Islamabad, 44000, Pakistan Department of Mathematics, College of Science, Abha, King Khalid University, Saudi Arabia Export Date: 4 March 2024 CODEN: JMMMD Correspondence Address: Wang, X.; College of Mechanical and Energy Engineering, China; email: sunxhking@aliyun.com Funding details: National Natural Science Foundation of China, NSFC, 12202102 Funding text 1: This research was supported by National Natural Science Foundation of China (Grant No.12202102), The authors are grateful to the support from Guangdong Provincial key Laboratory of Distributed Energy Systems. LA - English DB - MTMT ER - TY - JOUR AU - Lelkes, János AU - Bak, Bendegúz Dezső AU - Kalmár-Nagy, Tamás TI - Vibrations and energy distribution in inhomogeneous rods with elastic and viscous boundary conditions JF - SCIENTIFIC REPORTS J2 - SCI REP VL - 14 PY - 2024 IS - 1 PG - 16 SN - 2045-2322 DO - 10.1038/s41598-024-52860-4 UR - https://m2.mtmt.hu/api/publication/34562518 ID - 34562518 N1 - Export Date: 19 February 2024 Correspondence Address: Lelkes, J.; Department of Fluid Mechanics, Műegyetem rkp. 3., Hungary; email: lelkes.janos@gpk.bme.hu Funding details: Nemzeti Kutatási, Fejlesztési és Innovaciós Alap, NKFIA, NKFI K 137726 Funding text 1: This work has been supported by the Hungarian National Research, Development and Innovation Fund under contract NKFI K 137726. The research reported in this paper and carried out at BME has been supported by the ÚNKP-22-3 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund. The authors acknowledge the help of Mr. Ádám Zsiros with the initial, as well as the reviewers for their useful comments. Funding text 2: The research reported in this paper is part of project no. TKP-6-6/PALY-2021. Project no. TKP-6-6/PALY-2021 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021-NVA funding scheme. AB - Functionally graded materials have broad engineering applications including mechanical engineering, electronics, chemistry, and biomedical engineering. One notable advantage of such materials is that their stiffness distribution can be optimized to avoid stress concentration. A novel approach for solving the equations describing the longitudinal vibration of functionally graded rods with viscous and elastic boundary conditions is proposed. The characteristic equation of the system is derived for the solution of the undamped case for the constant stiffness rod. Then, a homotopy method is applied to compute the eigenvalues and mode shapes of graded rods for viscoelastic boundary conditions. The changes of the eigenvalues and mode shapes as function of the damping parameters are investigated. The optimal damping of the system is computed. It is shown that the qualitative behavior depends on the relation between the actual damping and the optimal damping of the system. The energy density distribution of graded rods is also discussed. An energy measure, the mean scaled energy density distribution is introduced to characterize the energy distribution along the rod in the asymptotic time limit. The significance of such a measure is that it reveals how the energy tends to distribute along the rod. It is shown that the energy distribution can be manipulated by changing the damping parameters. Qualitative changes depending on the relation between the actual damping and the optimal damping are highlighted. LA - English DB - MTMT ER - TY - JOUR AU - Papp, Bálint AU - Kristóf, Gergely TI - Predicting Concentration Fluctuations of Locally Emitted Air Pollutants in Urban-like Geometry Using Deep Learning JF - PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING J2 - PERIOD POLYTECH MECH ENG VL - 68 PY - 2024 IS - 1 SP - 44 EP - 52 PG - 9 SN - 0324-6051 DO - 10.3311/PPme.23391 UR - https://m2.mtmt.hu/api/publication/34495646 ID - 34495646 N1 - Funding Agency and Grant Number: Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund [TKP-6-6/PALY-2021, TKP2021-NVA]; New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund [UNKP-22-3-II-BME-109]; Gedeon Richter Talent Foundation Funding text: Project no. TKP-6-6/PALY-2021 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021-NVA funding scheme. Balint Papp's contribution to this paper was supported by the UNKP-22-3-II-BME-109 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund; as well as by the Gedeon Richter Talent Foundation (registered office: Gyoemroi ut 19-21, 1103 Budapest, Hungary) , established by Gedeon Richter Plc., within the framework of the Gedeon Richter PhD Scholarship. AB - The accurate quantification of concentration fluctuations is crucial when evaluating the exposure to toxic, infectious, reactive, flammable, or explosive substances, as well as for the estimation of odor nuisance. However, in the field of Computational Fluid Dynamics (CFD), the industry currently relies predominantly on steady-state RANS turbulence models for simulating near-field pollutant dispersion, which are only capable of producing the time-averaged concentration field. This paper presents a regression relationship for calculating the standard deviation of the local concentration based on the mean concentration and the downstream distance from a point source, over a city-like surface, in the case of the wind direction perpendicular to the streets. The desired peak values and other statistical characteristics can be predicted by assuming a gamma distribution which is fitted based on the average and standard deviation. To obtain the regression function, a deep neural network model was used. The model was trained using time-resolved concentration data obtained from wind tunnel experiments. The validation results show that the concentration fluctuations predicted by the DNN-based model are in satisfactory agreement with the measurement data in terms of the skewness, the kurtosis, the median, and the peak concentrations. Furthermore, the present paper suggests a workflow for estimating the concentration fluctuations based on RANS CFD results, as well as recommendations for generating further training data for specific applications. LA - English DB - MTMT ER - TY - GEN ED - Vad, János ED - Horváth, Csaba ED - Benedek, Tamás TI - International Journal of Turbomachinery, Propulsion and Power. Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22 TS - Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22 PY - 2023 UR - https://m2.mtmt.hu/api/publication/34518816 ID - 34518816 LA - English DB - MTMT ER - TY - JOUR AU - Kocsis, Bálint AU - Horváth, Csaba TI - Further development of rotating beamforming techniques using asynchronous measurements JF - Journal of Theoretical and Computational Acoustics J2 - J THEOR COMPUT ACOUS VL - Online Ready PY - 2023 PG - 25 SN - 2591-7285 DO - 10.1142/S2591728523400066 UR - https://m2.mtmt.hu/api/publication/34518784 ID - 34518784 N1 - Correspondence Address: Kocsis, B.; Department of Fluid Mechanics, Muegyetem rkp. 3, Hungary; email: kocsis.balint@gpk.bme.hu AB - When rotating noise sources, such as turbomachinery, are investigated using phased microphone array measurements and beamforming, sidelobes appear on the resulting beamforming maps. Sidelobes can be decreased by increasing the number of microphones. However, if the investigated phenomenon is steady, then there is a cost-effective alternative: performing asynchronous measurements using phased arrays having a limited number of microphones. The single beamforming maps can be combined in order to arrive at results that are superior in resolution and sidelobe levels. This technique has been investigated in the literature, but according to the authors’ best knowledge, has not yet been applied to turbomachinery. This article introduces a means for applying the asynchronous measurement technique and the combination methods for rotating noise sources. The combination methods are demonstrated on two rotating point sources (both in simulations and measurements), and then on an axial flow fan test case. In the case of the two rotating point sources, the achievable improvement in resolution, average-, and maximum sidelobe levels are shown as compared to the single results. In the case of the axial flow fan, it is demonstrated that the combination methods provide more reliable noise source locations and reveal further noise sources. LA - English DB - MTMT ER - TY - CHAP AU - Koren, Márton AU - Kristóf, Gergely ED - Molnár, Dániel ED - Molnár , Dóra TI - Mezoskálás hatások szerepe az áramlási térre és a terjedésre explicit érdességi rétegben T2 - XXVI. Tavaszi Szél Konferencia 2023 PB - Doktoranduszok Országos Szövetsége (DOSZ) CY - Budapest SN - 9786156457370 PY - 2023 SP - 501 EP - 519 PG - 19 UR - https://m2.mtmt.hu/api/publication/34499886 ID - 34499886 LA - Hungarian DB - MTMT ER - TY - CHAP AU - Horváth, Dávid András AU - Kalmár-Nagy, Tamás ED - Csüllög, Mihály ED - Mankovits, Tamás TI - ‪Semi-Empirical Method to Approximate the Poincaré-Lyapunov Constant for the Delayed-Liénard Equation‬ T2 - Book of Abstracts from 9th International Scientific Conference on Advances in Mechanical Engineering PB - University of Debrecen CY - Debrecen SN - 9783036414454 PY - 2023 SP - 39 UR - https://m2.mtmt.hu/api/publication/34496635 ID - 34496635 LA - English DB - MTMT ER - TY - JOUR AU - Lendvai, Bálint AU - Benedek, Tamás TI - Experimental and numerical investigation of the blade tip-related aeroacoustic sound source mechanisms of a ducted low-speed axial flow fan JF - APPLIED ACOUSTICS J2 - APPL ACOUST VL - 215 PY - 2023 SN - 0003-682X DO - 10.1016/j.apacoust.2023.109705 UR - https://m2.mtmt.hu/api/publication/34299741 ID - 34299741 N1 - Export Date: 24 November 2023 CODEN: AACOB Correspondence Address: Lendvai, B.; Department of Fluid Mechanics, Bertalan Lajos Street 4-6, Hungary; email: lendvai.balint@gpk.bme.hu LA - English DB - MTMT ER - TY - JOUR AU - Kovács, Kinga Andrea AU - Balla, Esztella Éva TI - Parameter Identification of the Lagrangian-averaged Vorticity Deviation Vortex Detection Method Through the Investigation of Fluid Flow Around Solid Bodies JF - PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING J2 - PERIOD POLYTECH MECH ENG VL - 67 PY - 2023 IS - 4 SP - 293 EP - 302 PG - 10 SN - 0324-6051 DO - 10.3311/PPme.22874 UR - https://m2.mtmt.hu/api/publication/34234013 ID - 34234013 N1 - Funding Agency and Grant Number: Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund [143204]; Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund [TKP-6-6/PALY-2021] Funding text: Project no. 143204 has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, financed under the OTKA K 22 funding scheme. Project no. TKP-6-6/PALY-2021 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021-NVA funding scheme. AB - The main focus of the current paper is the detection of vortices in fluid flow around a circular cylinder and a square cylinder, with an emphasis on the identification of the parameters used for vortex detection. The authors aim to enhance the practicality of an existing vortex detection method (Lagrangian-averaged vorticity deviation) by providing recommendations for the settings of the vortex detection parameters. The simulations were carried out using ANSYS Workbench 2022 R2, encompassing Reynolds numbers between 12 and 140, and angles of incidence from 0(degrees) to 45(degrees). The vortex detection was performed using MATLAB R2020b. The paper provides a comprehensive description of the parameters involved in the detection process and their significance, as well as the implementation of the parameter identification. The study results in the determination of the suggested parameter ranges, and a comparative analysis of different vortex detection methods is also presented for the case of the circular cylinder. LA - English DB - MTMT ER -