Dantec Dynamics as we know it today has its roots in the “Electronics Department” established by Dansk Industri Syndikat (DISA) in 1947.
DISA became interested in electronics – a completely new field in those days – as early as the 1930s. A few years later, in 1943, four Danmarks Radio employees set up a laboratory to undertake development projects in the field of low-current electronics.
DISA became interested in the laboratory’s activities, which complemented the work that it was itself involved in, as well as its future plans. The four colleagues moved their laboratory to DISA’s premises. The company’s electronics activities were gathered in the Electronics Department in 1947 – now considered the year Dantec Dynamics was born.
The department very soon began to develop a wide range of high-quality products for use both in medicine and the measurement of pressure and rotation. One of these early products, DISATAC, measures rotation in turbochargers and is still sold to the marine and offshore industries.
During the 1950s, the company developed its knowledge and expertise in flow measurement – know-how that provided the foundations for Dantec Dynamics’ current position as the world’s leading supplier of instrumentation for flow measurement and particle characterisation.
Since then, Dantec Dynamics has continued to innovate and deliver groundbreaking products to companies and institutions around the world. Some key milestones:
1958 – Constant Temperature Anemometry (CTA)
Point measurement of turbulence
The company launched the world’s first commercial Constant Temperature Anemometer (CTA) in 1958.
1971 – Laser Doppler Anemometry (LDA)
From intrusive to non-intrusive measurement of turbulence
DISA Elektronik was the first company to launch a commercial LDA system in 1971.
A frequency tracker was used to process the signal.
1978 – Towing Tank (LDA)
In 1978, a 3D towing tank LDA system was delivered to the Hamburg Ship Model Basin, HSVA. The optomechanical system included an Argon-Ion laser, beams splitting and frequency shifting optics, prisms guiding the laser beams into a streamlined strut, and a submerged housing with focusing optics, receiving optics and photo-detectors.
1982 – Fiber Optics (LDA)
From bulky to compact and flexible LDA solutions
When fiber optics technology became available, it became possible to decouple the heavy and bulky Argon-Ion lasers from the rest of the optics in LDA systems. Thanks to this development, miniaturization of the optics became possible.
1987 – Particle Dynamics Analysis (PDA)
From velocity only to velocity and particle size
A new product line, Particle Dynamics Analysis (PDA), was launched. It was an extension of the LDA technology, adding particle size to the measurable quantities.
1987 – Burst Spectrum Analyzer (BSA)
A new signal processor using hardware-based FFT analysis of LDA signals significantly improved the robustness of the results when measuring on noisy signals.
1994 – Particle Image Velocimetry (PIV)
Real-time planar turbulence measurements
Where CTA and LDA describe the flow at a single point, PIV provides information about how the velocity is distributed in a plane.
Digital PIV surfaced seriously for the first time at the end of the 1980s, using wet film as the recording medium. The “Data rate” was 1-2 measurements per day. Double exposures of particle images had to be scanned into digital form for processing on a computer. The digitized images were then processed using autocorrelation techniques. This technique could find the magnitude and direction of the velocity, but not the sign. To get the sign as well, two separate images are required and the processing is done by cross-correlation.
CCD cameras were the disruptive technology that made it possible to skip the time- consuming wet film development and acquire double images on-line. With advances in computer speed, it became viable to even process the data on-line. Building on these technological developments, Dantec began to develop a PIV product. At the 1994 Lisbon conference, real-time PIV results from a wind tunnel measurement were shown for the first time.
1996 – Traverse System for Full-scale Automotive Wind Tunnel
Dantec developed a number of large custom-built traverse mechanisms for full scale automotive wind tunnels. State-of-the-art Finite Elements Simulations made it possible to optimize the design for high stiffness and low flow disturbance.
1997 – Submersible Towing Tank (PIV)
The pulsed lasers used for PIV became smaller and cheaper, making it possible to make submersible PIV solutions for water tanks. The world’s first towing tank PIV system was delivered in 1997.
This has since been followed by many other submersible PIV systems installed in towing tanks and wave basins.
2000 – Time-resolved PIV
From Hz to kHz acquisition rates
Camera, laser, and computer technologies continued evolving. In 2000, Dantec launched the first commercial Time-Resolved PIV (TR-PIV) system with frame rates greater than 1,000 frames per second. Today, it possible to acquire 1 MegaPixel images at rates up to more than 25,000 frames per second, and reduced resolution images at up to more than 1 million frames per second, moving the bottleneck from the acquisition of images to the processing of the data.
2000s – Combustion Diagnostics and Spray Imaging
From velocity only to temperature, species concentration, particle size, mixing phenomena, spray analysis
In this millennium, imaging techniques have diversified into other applications such as combustion diagnostics using Laser Induced Fluorescence (LIF) and spray diagnostics, which can be combined with PIV to make multi-parameter measurements.
This helps researchers understand the interaction between fluid dynamics, thermodynamics, and chemical reactions in combustion processes, fuel injection spray interactions with the flow in combustion engines, and many other applications.
2010 Volumetric Velocimetry (VV)
From planar to volumetric PIV
PIV started as a 2D2C technique: measurement in a plane (2D) of two velocity components (2C). This soon evolved into 2D3C, stereo PIV, measuring 3 velocity components in a plane.
The latest evolution of the technique is volumetric velocimetry, also known as tomographic PIV. With this technique, particle positions are reconstructed in a volume based on images from at least two but typically four cameras. This technique sets puts new demands on laser power because a whole volume rather than a plane must be illuminated. With several cameras and computationally heavy reconstruction algorithms, computing power is challenged as well.
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