Problems: transmission errors, transmission errors, emissions of structure-borne noise and noise, mechanical wear on components
Goal: Optimal design of wind turbine gearboxes, reduction of structure-borne noise emissions
Each gearbox and the individual parts installed in it are subject to manufacturing tolerances that vary depending on the purpose and location of use of the entire assembly. Due to these manufacturing tolerances in combination with the temperature and load-dependent component elasticities as well as assembly influences, the transfer function of the rotational movement and the torque deviates from the ideal transfer function. This phenomenon is also known as TE (Transmission Error). The more complex a transmission is constructed, i.e. the more gear stages including shafts, wheels and bearings a transmission has, the larger the sum of the individual transmission errors becomes. The consequences of the transmission errors are manifested by increased macroscopic and microscopic wear on the components and component surfaces. Furthermore, they are acoustically perceptible to people due to the emission of structure-borne noise and noise. Therefore, a measurement of the transmission error is necessary. This ensures that the error of each individual gear stage can be quantified.
Consequently, design-related influences, which differ greatly between spur or planetary gears, for example, as well as tooth mesh errors can be analyzed using suitable measurement technology. Using powerful software, order and frequency spectra can be generated in two- and three-dimensional representation and correlations between transmission errors and structure-borne noise emissions can be found. In order to record measurement data, high-resolution incremental sensors are applied to the transmission input and output shafts. However, eccentricities or wave impacts cause measurement errors. Therefore, for large shaft diameters, two speed sensors offset by 180° can be used to eliminate measurement errors in the software. Depending on the shaft diameter, different types of sensors are available, such as one-piece hollow shaft encoders or a two-part sensor system with a separate sensor head and a magnetic tape that spans the shaft. In addition, ideally additional speed sensors are installed on the intermediate shafts inside the transmission. In parallel to the speed detection, structure-borne noise is measured using acceleration sensors at different points in the transmission.
The measured values recorded are evaluated in the time and spectral range.
ROTEC ENGINEERING also supports you with technical engineering knowledge on problems relating to vibration analyzes on engines, transmissions and drive trains. With our know-how, we make a valuable contribution to your product in the areas of timing train validation, valve train optimization, clutch design, transmission errors (TE), transmission and oil balance optimization, drive train measurement and optimization, current and voltage analysis as well as the application of measurement technology.
Analyzes in the time domain
- Dynamic twist angle between transmission input and output shafts
- Load-dependent gearbox stiffness
- Speed-independent vibration developments and structure-borne noise emissions
Analyzes in the spectral range
- Examination of tooth meshing by forming order or frequency spectra
- Representation of 3D sequences by linking the spectra from several individual measurements, e.g. via load or speed
- Creation of 2D sectional representations over load or speed to select individual orders or frequencies 2D representation to investigate correlations between transmission errors and structure-borne noise emissions
Problems: Mechanical damage to the system, broken shaft of the turbine
Goal: Optimal design of the turbines, prevention of superimposition of torsional vibrations due to frequency fluctuations in the network
Turbines for generating energy can be designed as gas or steam turbines. The increasing development of turbines is moving towards larger and more efficient rotating machines. Due to the enormous mass and speed during operation, the turbines have enormous energy. Critical torsional vibrations can occur both during planned ramp-up and shutdown of turbines for maintenance (“outage season”) and during continuous operation. They lead to mechanical damage, including shaft breakage, and should therefore be avoided. Mains frequency fluctuations in particular can cause torsional vibrations in the turbine during continuous operation. A torsional vibration analysis makes it possible to avoid critical operating points and ensure safety. The aim here is to prevent the torsional vibration from being superimposed by frequency fluctuations in the network, feedback effects and the natural frequency of the system.
The speed measurement of turbines is usually carried out using magneto-resistive sensors on gears. This involves measuring variables such as single-channel variables such as the oscillation angle and using the angular velocity key figure. It is also possible to measure the twist angle between the start and end of the rotor during operation in order to be able to view the dynamic torsion. Measurements over a longer period of time allow insights into the endurance capability under different load conditions to be obtained. These arise from loads from the energy network.
The measured values recorded are evaluated in the spectral range.
ROTEC ENGINEERING also supports you with technical engineering knowledge on problems relating to vibration analyzes on engines, transmissions and drive trains. With our know-how, we make a valuable contribution to your product in the areas of timing train validation, valve train optimization, clutch design, transmission errors (TE), transmission and oil balance optimization, drive train measurement and optimization, current and voltage analysis as well as the application of measurement technology.
Frequency spectra/spectrogram
- Series of high-resolution frequency spectra;
- Frequency resolution: 1/40 Hz, 1/100 Hz, …
- Individual speed measuring points (oscillation angle and angular acceleration) as well as the difference between two speed measuring points (twisting angle, dynamic torsion)
- Even very small oscillation angles (< 1/1000 degree) because of the 12.3 GHz counter on the ROTEC speed measurement card
- Identification of resonance points during acceleration and coasting down
