By : Shreedhar Singh
GTRE is implementing several critical upgrades to enhance the performance, reliability, and efficiency of the Kaveri engine. These improvements aim to make it viable for integration with modern fighter platforms and unmanned systems.
1. Thermal Capability Upgrade with CMSX-4 Turbine Blades
GTRE is replacing the current directionally solid turbine blades—which handle up to 1050°C—with second-generation single crystal blades (CMSX-4). These blades can operate at 1080°C, and when combined with thermal barrier coatings and advanced cooling hole designs, the engine’s Turbine Entry Temperature (TET) will rise from 1450°C to 1500°C. This change significantly improves the thermal efficiency and durability of the engine.
2. Enhanced Thrust-to-Weight Ratio
GTRE is working to increase the engine’s thrust-to-weight ratio from 6.5 to 8. To reduce overall weight:
- GTRE is introducing blisks (bladed disks) in the 3 Low-Pressure Compressor (LPC) stages and 6 High-Pressure Compressor (HPC) stages. This design reduces component weight by 25% to 30% compared to conventional blade-disc assemblies.
- On the turbine side, GTRE is adopting a boltless blade arrangement, further contributing to weight reduction and increased structural integrity.
3. Polymer Matrix Composite (PMC) By-Pass Duct
GTRE has developed a Polymer Matrix Composite-based by-pass duct for the Kaveri engine. It offers a significant weight advantage—6 kg lighter than its metallic counterpart—without compromising structural performance. This lightweight component enhances the overall thrust-to-weight ratio and contributes to better fuel efficiency.
4. New Fan Design for Better Distortion Tolerance
To address the high inlet pressure distortion caused by serpentine intakes used in stealth aircraft, GTRE has designed a new fan with high tolerance to pressure fluctuations:
- The fan provides a 25% surge margin, improving operability under distorted flow conditions.
- GTRE has incorporated Variable Inlet Guide Vanes (VIGVs) with wide-chord blades to suppress flutter and enhance stability.
- A 3D stacking technique is used to reduce aerodynamic losses and manage secondary flow interactions.
Fan Specifications:
- Bypass Ratio: 3.4:1
- Mass Flow Rate: 78 kg/s
- Efficiency: 86%
5. Powder Metallurgy Discs for Hot Section Durability
GTRE, in collaboration with DMRL, is developing Powder Metallurgy (PM) turbine discs to withstand high thermal and mechanical stresses in the engine’s hot section. PM discs offer improved creep resistance and mechanical strength, essential for long-term performance. For this, India is setting up a 50,000-tonne forging press—a key enabler for indigenous high-performance aerospace components.
6. Resolving the Afterburner Deficiency
The afterburner has long been a limiting factor in the Kaveri engine. While the dry version produces 49 kN of thrust, the afterburner fails to deliver even 30 kN. GTRE has partnered with BrahMos Aerospace to develop a new afterburner based on GTRE’s design. This collaboration is expected to finally address the afterburner shortfall and unlock the engine’s full potential for combat aircraft applications.