Article
Thermodynamics
R. J. Talapati, V. V. Katti, N. S. Hiremath
Summary: The experimental study focuses on the local heat transfer characteristics of synthetic air jet impinging on convex surface. The results show that the local heat transfer is strongly influenced by actuator frequency and jet to plate distance. The combination of an actuator frequency of 200 Hz and a lower jet to plate distance of 2 is observed to be effective across all conditions.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Engineering, Mechanical
Katherine Kokmanian, Diogo C. Barros, Marcus Hultmark, Pierre Dupont
Summary: The S-NSTAP probe was deployed in a supersonic wind tunnel to gather data on freestream and boundary layer measurements at M-infinity = 2, showing superior temporal resolution compared to conventional hot-wires. Sensitivity coefficients varied between probes, with the S-NSTAP exhibiting a coefficient half the size of the conventional probe, and experimental data were compared to numerically modeled results for turbulent boundary layers.
EXPERIMENTS IN FLUIDS
(2021)
Article
Mechanics
Jangyadatta Pasa, Samarendra Panda, Venugopal Arumuru
Summary: In this study, a novel technique is proposed and demonstrated to enhance the strength of a synthetic jet array (SJ array) by providing a non-linear phase delay between the actuators. The results show that the best focusing effect of the SJ array is achieved when the Strouhal number is 0.086 and the non-linear phase delay is 90 degrees.
Article
Thermodynamics
T. Helmig, R. Kneer
Summary: Heat transfer at moving bearing interfaces is crucial for the thermal design of high precision machine tools and electrical engines. Traditional methods using tactile sensors have limitations like measurement uncertainties and long investigation times. A novel approach using infrared thermography overcomes these limitations and provides more accurate and efficient results.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Engineering, Electrical & Electronic
Samarendra Panda, Jangyadatta Pasa, Venugopal Arumuru
Summary: This paper presents the hot-wire measurements of a novel coaxial synthetic jet (CSJ) actuator, which is formed by positioning two single-acting synthetic jet (SJ) actuators coaxially with their own flow actuation mechanism. The CSJ actuator utilizes periodic suction and expulsion of fluid through orifices to create flow, and the independent control of excitation voltage, frequency, and phase difference enhances its strength and spreading without additional power investment.
SENSORS AND ACTUATORS A-PHYSICAL
(2023)
Article
Thermodynamics
Joseph L. Pointer, Christopher A. Roseman, Brian M. Argrow, Dale A. Lawrence
Summary: A small-scale wind tunnel was developed to calibrate balloon-born fine-wire anemometers for stratospheric conditions. The system allows calibration of hotwire anemometers to test gases at specific flow velocities and pressures. Experimental testing and numerical simulations were conducted to validate the procedure for calibration of hotwire anemometers and heat transfer relations at stratospheric pressure conditions.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2023)
Article
Engineering, Chemical
Pietro Rando, Marco Ramaioli
Summary: Food 3D Printing is a novel technology that involves manufacturing edible objects with customized shape and structure. The study focuses on the interplay between the rheological and thermal properties of chocolate products, and printing conditions, in order to predict the stability of 3D printed structures. The research proposes a stability criterion based on the local yield stress to explain the stability or collapse of the 3D printed structures.
JOURNAL OF FOOD ENGINEERING
(2021)
Article
Mechanics
Udaysinh S. Bhapkar, Abhishek Mishra, Harekrishna Yadav, Amit Agrawal
Summary: This experimental study investigated the flow characteristics of synthetic jets emitted from different orifice shapes. The results showed that the wall jet from the elliptical orifice had higher energy-containing vortices and a delayed self-similarity compared to other orifice shapes. The elliptical orifice also had relatively higher normal and shear stresses. In addition, for a larger nozzle to surface spacing, the rectangular orifice shape resulted in a shifting of the self-similarity location.
Article
Thermodynamics
Kiyun Kim, Pravesh Pokharel, Taiho Yeom
Summary: This study investigates the convection heat transfer enhancement of a heated surface in an airflow channel using a synthetic jet. Numerical simulation and flow visualization experiments reveal that the vortex packets generated by the synthetic jet directly impact or sweep the heated surface, leading to significant heat transfer enhancement.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
V. V. Lemanov, M. A. Pakhomov, V. Terekhov, Z. Travnicek
Summary: Heat transfer in a synthetic impinging jet at different pulse frequencies is investigated experimentally and numerically. The study provides measurements and numerical predictions of average and fluctuating heat transfer, and analyzes the effects of various parameters.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
F. Todd Davidson, David Helmer, Collin Parker, Lee Cox, Kalen Kahn, Christopher J. Elkins, John P. Clark, Nathan Humbert, Bret P. Van Poppel, Michael J. Benson
Summary: This study reports the results of paired experiments for the aft section of a complex internal cooling flow within a gas turbine vane using Magnetic Resonance Velocimetry (MRV) and steady-state Infrared (IR) thermography. The results provide important information about flow distribution, impingement hole performance, and cross flow effects, which are crucial for the study of vane cooling.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Energy & Fuels
Jan Stasiek, Adam Stasiek, Marek Szkodo
Summary: The main goal of the research presented in this paper was to experimentally and numerically analyze heat enhancement and aerodynamic phenomena during airflow in a channel equipped with flow turbulators in the form of properly configured ribs. The use of ribs intensifies heat transfer while increasing flow resistance and energy costs. Optical tools such as Liquid Crystal Techniques, Particle Image Velocimetry, and Digital Image Processing are utilized to measure temperature, velocity, friction factor, and heat transfer coefficient.
Article
Engineering, Multidisciplinary
JunWen Tan, YuanWei Lyu, JingZhou Zhang, JingYang Zhang
Summary: A novel concept of improving square-array jet impingement heat transfer by integrating a synthetic jet actuator into the array unit is proposed and experimentally investigated. The results show that the synthetic jet has minor influence on the stagnation heat transfer of square-array jet but significantly improves the local heat transfer at the central zone of the array unit. Its potential is closely related to the array layout, Reynolds number, and impinging distance.
SCIENCE CHINA-TECHNOLOGICAL SCIENCES
(2023)
Article
Materials Science, Composites
Vahid Daghigh, Mohammad Naraghi
Summary: Infrared thermography is widely used for void and defect detection in materials, and the inverse heat transfer problem is solved using the k-nearest neighbors machine learning algorithm to predict defect attributes in composite laminates. The study uses simulated data from finite element analysis to train the ML algorithm.
COMPOSITES SCIENCE AND TECHNOLOGY
(2023)
Article
Energy & Fuels
Young Seo Kim, Jin Young Jeong, Jae Su Kwak, Heeyoon Chung
Summary: An experimental study investigated the effects of fan-shaped film cooling hole arrangement and density ratio on heat transfer coefficient augmentation. Results showed that smaller hole pitch and higher blowing ratio lead to increased heat transfer coefficient augmentation, while row-to-row distance and hole arrangement have negligible effects on heat transfer coefficient.
