Independent Field Validation of Real-Time Cylinder Peak Pressure Measurement Using a Single Sensor
Customer Profile
- Customer: International ship owner – Crude oil tanker fleet
- Asset: Auxiliary engines (two identical units)
- Engine make & model: CSSC MAN 6L23/30H
- Rated power: 960 kW @ 900 rpm
- Engine type: Four-stroke diesel generator
- Industry: Marine – Commercial Shipping
Context
Vib360 was installed on board as a Proof of Concept (PoC) to evaluate advanced condition-monitoring capabilities prior to potential fleet-wide deployment.
During normal vessel operation and routine daily use, the crew and technical management sought to validate the accuracy and repeatability of real-time cylinder-wise peak pressure values using a single sensor configuration.
The exercise was structured as an independent field validation under real operating conditions, rather than a controlled or laboratory test.
Problem Statement
Continuous cylinder-wise peak pressure monitoring is typically achieved using one pressure sensor per cylinder, resulting in higher hardware cost, installation complexity, and maintenance burden.
The customer required confirmation that Vib360 could reliably derive cylinder-wise peak firing pressure using a single reference sensor, while maintaining accuracy, repeatability, and operational relevance.
Objective of Vib360 Assessment
- Validate real-time derivation of cylinder-wise peak firing pressure using a single sensor
- Confirm repeatability across cylinders and engines
- Demonstrate physics-based measurement correlated to real combustion events
- Establish confidence for scalable deployment and routine operational use
Measurement Setup
- Flywheel-mounted Magnetic Pickup Unit (MPU)
- One cylinder peak pressure sensor used as a reference sensor
- Continuous torsional vibration and angular acceleration monitoring through Intelligent Controller
Validation was conducted at constant load to eliminate load-induced variability.
Two auxiliary engines at different maintenance stages were used:
- Recently overhauled engine (~1,300 running hours)
- Engine approaching major maintenance (~3,000 hours remaining)
Manual peak pressure measurements and Vib360-derived values were recorded in parallel with time synchronisation.
Physics-Based Findings
Vib360 analysed cycle-to-cycle torsional response and combustion-induced angular acceleration signatures.
Harmonic distortions associated with individual firing events were resolved to reconstruct cylinder-wise peak pressure.
The following observations were made:
- Vib360-derived peak pressure values matched manual measurements within agreed tolerances
- Cylinder-to-cylinder pressure relationships were accurately reproduced
- Results were repeatable across both engines and operating states
- Continuous peak pressure trends were stable and load-responsive
Mechanical / Operational Interpretation
The validation confirmed that combustion events generate distinct torsional signatures containing sufficient information to reconstruct cylinder-level pressure behaviour.
A single reference pressure sensor, combined with torsional physics, was shown to be adequate for decision-grade combustion monitoring.
Action Taken
Following successful validation:
- Peak pressure trends were incorporated into routine daily monitoring
- Manual peak pressure checks were retained only for periodic cross-verification
Outcome and Value
- Independent field validation of single-sensor peak pressure monitoring
- Improved crew and technical management confidence
- Reduced hardware and lifecycle cost compared with multi-sensor systems
- Retrofit-friendly architecture with minimal disruption
Technical Significance
This case establishes Vib360 peak pressure monitoring as a physics-based, repeatable, and scalable solution suitable for routine operational use and CBM-aligned maintenance decisions.
Note:
Similar trials were conducted on various other auxiliary Engine models such as: Hyundai-Himsen H21/32 (5 Cyl/6Cyl/ 8Cyl); Niigata 28HX (6Cyl/ 8Cyl); Niigata 28AHX(9Cyl); Bergen KRG (5Cyl/ 8Cyl); STX MAN 14V32/40; Wartsila-8L46B; MAK-6M43C; Yanmar8N21A.