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Woodward 9902-332

Product Name:​ VSV (Variable Stator Vane) Hydraulic Control Mechanism
Product Introduction:​ The 9902-332 is a classic model within Woodward’s VSV variable stator vane control series, designed for non-aviation gas turbines. Its function belongs to the same product family as 9902-337, used for positioning compressor variable stator vanes, preventing compressor stall, and ensuring efficient operation under partial-load conditions. This model is described alongside 9902-405 and 9902-406 in Manual 40110.
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Detailed content

Technical Specifications:
  • Inlet pressure: 138–586 kPa (20–85 psig)
  • Outlet pressure: 4654–5000 kPa (675–725 psig)
  • Drive speed: 0–5980 rpm
  • Rotation: Clockwise (CW)
  • Speed sensing range: 2400–6100 rpm
  • Hydraulic fluid: MIL-L-23699 or MIL-L-7808, filtration 10 µm
  • Normal oil temperature: 4 to 82 °C
  • Normal ambient temperature: –7 to +93 °C; extreme –29 to +121 °C (≤ 2% of service life)
  • Dry weight: 12 kg (26 lb)
  • Compliance: GEAE Spec M50TF1994
Functional Features:​ Precise compressor VSV angle control; prevention of low-condition compressor surge; improved engine start and variable-load performance; integrated tachometer pump for speed feedback.
Application Scenarios:​ GE LM series aeroderivative gas turbine VSV regulation; industrial gas turbine compressor variable geometry control; gas turbine systems requiring anti-surge optimization.
Structural Characteristics:​ Mechano-hydraulic integrated structure with tachometer pump serrated drive shaft; clearly labeled hydraulic ports; similar external appearance to 9902-405/406 but differing in rotation direction and pressure parameters.
Working Principle:​ Same as 9902-337 — electronic controller outputs hydraulic command → servovalve regulates hydraulic oil → drives actuator piston → rotates VSV vanes. The tachometer pump provides real-time speed feedback, forming a closed loop.
Installation Requirements:
  • Use lifting equipment for placement
  • Correctly align the tachometer pump serrated drive shaft for unimpeded rotation
  • Connect hydraulic lines per drawing
  • Perform calibration per manual after installation
Usage Precautions:
  • Do not interchange with 9902-337/405/406 based on appearance alone; must compare outlet pressure, rotation direction, and compliance standards
  • Confirm independent overspeed protection is in place before startup
  • Maintain hydraulic oil cleanliness; replace filter elements periodically
  • Complete zero and stroke calibration before commissioning
  • Comply with ESD protection procedures

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