Technical Description WT410S

     1. General Description

The WT410S (S = “Slim”) is a more compact variant of the standard model WT410. By reducing the width of the settling chamber (also “Settling Chamber”), the entire system can be transported in a high-cube container and operated directly within it. This design is particularly interesting for applications where mobility, compact dimensions, and worldwide usability are the main focus – for example, in university or industrial environments.

Operation inside the container is generally possible; however, the front and rear doors must be opened, as there is not enough space for air circulation when closed.

Assembly can be carried out by technically skilled personnel without requiring specific expert knowledge. This makes the WT410S particularly attractive for educational or research institutions.

 

Datasheet WT410S

 

Technical Data

Design Type		Open loop
Measuring cross section	mm	1000 x 1000
Measuring length	mm	1500
Max. windspeed	m/s	40
Turbulence	%	0.7
Contraction		4.6

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     2. Basic Structure

The WT410S is built in a modular way. All main components are designed to be bolted and disassembled if necessary. The basic structure consists of the following modules:

• Settling chamber with honeycomb straightener and multiple screens for flow smoothing

• Nozzle for flow acceleration

• Measurement chamber with access points and viewing windows

• Diffuser for wake relaxation

• Fan assembly with vibration isolation

Additionally, the system includes power electronics as well as a control unit with a touch display for regulating and monitoring the airflow.

For mobile applications, the wind tunnel can be equipped with rollers and divided into three functional assemblies:

• • Assembly 1: Settling chamber, nozzle, and control unit (touch display)

  • Assembly 2: Measurement chamber

  • Assembly 3: Diffuser 1 and fan with mounted power electronics

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     3. Flow Conditioning and Turbulence Level

The flow conditioning of the WT410S is designed for a low turbulence intensity while maintaining a compact build. The settling chamber contains honeycombs to align swirl and skewed flows, followed by several screens arranged from coarse to fine mesh for further flow smoothing.

The air then passes through an aerodynamically shaped nozzle that accelerates the flow. The transitions between components – particularly between flow straightener, nozzle, and diffuser 1 – are optimized to create thin boundary layers and prevent flow separation.

A crucial factor in flow quality is the fan assembly. For the WT410S, blade configuration and settings are individually tested and adjusted to match the intended operating conditions.

As a compromise wind tunnel, the WT410S uses a contraction ratio of 4.6, balancing transportability and flow quality. By comparison, high-performance fixed installations typically have contraction ratios of 9 or higher.

An optional integrated turbulence measurement system can be added, directly connected to the control system, enabling continuous monitoring of turbulence levels during operation. This allows early detection and analysis of structural vibrations or model interactions.

For advanced applications, an optional turbulence optimization system can be installed in the first diffuser (Diffuser 1), further reducing residual flow disturbances and minimizing turbulence.

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     4. Drive Concept

The WT410S uses an axial fan mounted with vibration isolation on a spring-supported system. The connection to the rest of the tunnel structure is via a flexible coupling, preventing mechanical vibrations from transferring to other components.

The fan is controlled by frequency-regulated power electronics, including a frequency inverter, line chokes, and filters. This allows smooth operation from around 10 % to full load. An optional low-speed version enables precise control starting from about 2 % of maximum speed, ideal for low-velocity applications.

Integrated line filters and chokes protect sensitive environments, particularly where delicate measurement equipment is used, preventing electrical feedback into the power grid and minimizing interference.

The drive system is linked to the control unit, which handles airflow setpoint input and regulation. Operation is possible via the local touch display or remotely through dedicated software.

Alternatively, the WT410S can operate without the control unit, with direct regulation via the power electronics. A 0–10 V analog interface allows control via a potentiometer or an external customer control system, ideal for simple test setups or integration into existing control architectures.

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     5. Control, Regulation, and Software

The WT410S comes standard with a control unit featuring a touch display. This display provides real-time wind tunnel operating data, collected from a separate sensor box measuring barometric pressure, dynamic pressure via Pitot tubes, air temperature, and humidity. From these values, the current wind speed is continuously calculated and displayed.

Users can set desired flow speeds directly on the display, and the control system automatically adjusts the fan speed accordingly. Remote operation via software is also available.

The software offers extended functions, such as data logging and customizable automated test sequences (e.g., ramps, steps, or cyclic programs), particularly useful for experimental applications and endurance testing.

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     6. Detailed Module Descriptions

• • Settling Chamber: Steel frame construction with galvanized sheet panels, honeycomb flow straightener, and three tensioned stainless-steel screens. Access panels allow easy cleaning without disassembly.

  • Nozzle: Galvanized sheet metal, polynomially shaped (7th or 9th order), with slight convergence for optimal acceleration and integrated Pitot tube port. Contraction ratio 4.6 for compactness and reduced turbulence.

  • Test Section: Galvanized steel on a welded frame, large glass windows on sides and top (optional Plexiglas), optional hinged openings, optional removable floor inserts for scales, turntables, tilt rigs, or custom mounts.

  • Diffuser: Galvanized sheet steel, optimized gradient to avoid separation, optional flow-optimizing elements or safety grating.

  • Fan Assembly: Galvanized steel fan, vibration-isolated mounting, safety screen at outlet.

  • Coating: Internal surfaces coated with 2-component polyurethane paint, standard color telegray (RAL 7047). Optional matte black coating for optical or photographic measurements.

  • Stainless Steel Option: Complete stainless steel construction available for special applications involving water or chemical exposure.

  • Mobility and Quick-Connects: Optional industrial castors and quick-release connections for fast assembly/disassembly, ideal for mobile setups.

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      7. Test Section Size and Blockage

The WT410S has a 1000 mm × 1000 mm test section, allowing tests with larger models or components. The blockage factor (model frontal area relative to test section area) should be considered:

• • For general experimental research, blockage factors of 20 % or more can be acceptable if effects are understood and corrected for.

  • For high-accuracy calibration (e.g., anemometer calibration under MesNet standards), maximum blockage is 5 %.

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      8. Noise Levels

Measurements taken 2 m from the wind tunnel outlet (comparable model WT404):

Flow speed [m/s]	Sound level [dB(A)]
10	64
15	76
20	81
25	87
30	93
35	97
40 (v_max)	102

At full speed (40 m/s), the sound level reaches approx. 102 dB(A), requiring hearing protection. Lower speeds result in significantly reduced noise levels.

Optional soundproofing in the first diffuser and additional silencers can reduce noise by up to 12 dB(A).

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      9. Development History

The WT410S evolved from earlier WT409 series models. The new WT4xxS series (WT409S, WT410S, WT411S, WT412S) was developed to create high-performance wind tunnels that are globally shippable and mobile. The main challenge was the size of the settling chamber, which exceeded container dimensions in earlier models.

The S-series addresses this with a more compact settling chamber and reduced contraction ratio, enabling full transport in high-cube containers. This feature later inspired container-based operation, including in refrigerated or climate-controlled containers, making the WT410S a mobile, container-ready precision wind tunnel.

 

 

Accesories

Power electronics

Windtunnel control

⚠️ Note: Any power electronics or control units shown in images are not included in the base price and must be purchased separately.