GTRE GTX-35VS Kaveri

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GTRE GTX-35VS Kaveri
GTRE GTX-35VS Kaveri

The GTX-35VS Kaveri is a low-bypass-ratio afterburning turbofan being developed by the Gas Turbine Research Establishment (GTRE) of Bangalore, India. The Kaveri engine is an indigenous Indian design intended to power production models of the HAL Tejas fighter, otherwise known as the "Light Combat Aircraft" (LCA) as well as the proposed Medium Combat Aircraft (MCA).

Contents

[edit] Design

The Kaveri is a low-bypass-ratio (BPR) afterburning turbofan engine featuring a six-stage core high-pressure (HP) compressor with variable inlet guide vanes (IGVs), a three-stage low-pressure (LP) compressor with transonic blading, an annular combustion chamber, and cooled single-stage HP and LP turbines. The development model is fitted with an advanced convergent-divergent ("con-di") variable nozzle, but the GTRE hopes to fit production Tejas aircraft with a multi-axis thrust-vectoring version.

The Kaveri engine has been specifically designed for the demanding Indian operating environment, which ranges from hot desert to the highest mountain range in the world. The GTRE's design envisions achieving a fan pressure ratio of 4:1 and an overall pressure ratio of 27:1, which it believes will permit the Tejas to "supercruise" (cruise supersonically without the use of the afterburner). The Kaveri is a variable-cycle, flat-rated engine and has 13% higher thrust than the General Electric F404-GE-F2J3 engines equipping the LCA prototypes. Plans also already exist for derivatives of the Kaveri, including a non-afterburning version for an advanced jet trainer, and a high-bypass-ratio turbofan based on the Kaveri core.[1] Another concept being considered is an enlarged version of the Tejas with two engines fitted with fully vectoring nozzles, which might make the vertical tail redundant (the Tejas has no horizontal tail).[2]

An indigenous Full-Authority Digital Engine Control (FADEC) unit has been developed for the Kaveri (KADECU) by the Defence Avionics Research Establishment (DARE) of Bangalore. The Central Vehicle Research and Development Establishment (CVRDE) of Avadi was responsible for the design and development of the Tejas' aircraft-mounted accessory gear box (AMAGB) and the power take-off (PTO) shaft.

The general arrangement of the Kaveri is very similar to other contemporary combat engines, such as the Eurojet EJ200, SNECMA M88, General Electric F414, and Pratt & Whitney F119. At present, the peak turbine inlet temperature is designed to be a little lower than its peers, but this is to enable the engine to be flat-rated to very high ambient temperatures. Consequently, the bypass ratio that can be supported, even with a modest fan pressure ratio, is only about 0.16:1, which means the engine is really a "'leaky' turbojet" like the F404.

[edit] History

In 1986, the Indian Defence Ministry's Defence Research and Development Organisation (DRDO) was authorized to launch a programme to develop an indigenous powerplant for the Light Combat Aircraft. It had already been decided early in the LCA programme to equip the prototype aircraft with the General Electric F404-GE-F2J3 afterburning turbofan engine, but if this parallel program was successful, it was intended to equip the production aircraft with this indigenous engine.

The DRDO assigned the lead development responsibility to its Gas Turbine Research Establishment (GTRE), which had some experience in developing jet engines. Its initial attempt, the GTX37-14U afterburning turbojet, was the first jet engine to be designed entirely in India and it first ran in 1977.[2] A turbofan derivative, the GTX37-14UB, followed; however, the GTRE returned to turbojet technology with the greatly redesigned, but unsatisfactory, GTX-35. For the LCA programme, the GTRE would again take up a turbofan design which it designated the GTX-35VS "Kaveri". Full-scale development was authorised in April 1989 in what was then expected to be a 93-month programme projected to cost 3.82 billion rupees (nearly US$82 million at the time). There has been much criticism of the degree of realism in the DRDO's planning schedules for various elements of the LCA programme, most particularly for the Kaveri development effort. France's SNECMA, with over half a century of successful jet engine development experience, took nearly 13 years to bring the Rafale fighter's M88 engine to low-volume production after bench testing had begun; a similar timespan for the less-experienced GTRE would see Kaveri production beginning no earlier than 2009.[3]

The original plans called for 17 prototype test engines to be built. The first test engine consisted of only the core module (named "Kabini"), while the third engine was the first example fitted with variable inlet guide vanes (IGV) on the first three compressor stages. The Kabini core engine first ran in March 1995. Test runs of the first complete prototype Kaveri began in 1996 and all five ground-test examples were in testing by 1998. The initial flight tests were planned for the end of 1999, with its first test flight in an LCA prototype to follow the next year. However, progress in the Kaveri development programme was slowed by both political and technical difficulties.

The embargo imposed by the U.S. following India's May 1998 nuclear weapons tests forced General Electric to suspend delivery of the F404 engines that were to power the prototypes after only 11 F404's had been supplied.[4] Alternative engines were considered — including the Rafale's SNECMA M88-2, the Eurofighter's Eurojet EJ200, and the RD-93 variant of the MiG-29's Klimov RD-33 — but no decision had been made by the time sanctions were lifted in September 2001.[5] In February 2002, the U.S. government agreed to supply an additional 40 F404-F2J3 engines to permit flight testing of several previously engineless LCA prototypes to begin.[6]

Little information has been publicly released to date concerning the nature of the Kaveri's technical challenges, but it is known that the Kaveri has had a tendency to "throw" turbine blades, which required securing blades from SNECMA (as well as digital engine control systems).[7] Continuing development snags with the Kaveri resulted in the 2003 decision to procure the uprated F404-GE-IN20 engine for the eight pre-production Limited Series Production (LSP) aircraft and two naval prototypes. The ADA awarded General Electric a US$105 million contract in February 2004 for development engineering and production of 17 F404-GE-IN20 engines, delivery of which is to begin in 2006. In mid-2004, the Kaveri failed its high-altitude tests in Russia, ending the last hopes of introducing it with the first production Tejas aircraft.[8] This unfortunate development led the Indian Ministry of Defence (MoD) to order 40 more IN20 engines in 2005 for the first 20 production aircraft, and to openly appeal for international participation in completing development of the Kaveri. In February 2006, the ADA awarded a contract to SNECMA for technical assistance in working out the Kaveri's problems.[9] The DRDO currently hopes to have the Kaveri engine ready for use on the Tejas by 2009-10.

[edit] Development costs

Development of the Kaveri engine was projected in 1989 to cost Rs. 382.81 crores (nearly US$82 million). In Dec. 2004, it was revealed that the GTRE had spent over Rs. 1,300 crores (around US$295 million) on developing the Kaveri. Furthermore, the Cabinet Committee on Security judged that the Kaveri would not be installed on the LCA before 2012, and revised its estimate for the projected total development cost to Rs. 2,839 crores (more than US$640 million).[10] The DRDO, however, currently hopes to have the Kaveri engine ready for use on the Tejas by 2009-10.

[edit] Applications

[edit] Specification (GTX-35VS Kaveri)

General characteristics

  • Type: Afterburning turbofan
  • Length: 137.4 in (3490 mm)
  • Diameter: 35.8 in (910 mm)
  • Dry weight: 2,427 lb (1,100 kg) [Production model goal: 2,100 lb (950 kg)]

Components

  • Compressor: two-spool, with low-pressure (LP) and high-pressure (HP) axial compressors:
    • LP compressor with 3 fan stages and transonic blading
    • HP compressor with 6 stages, including variable inlet guide vanes and first two stators
  • Combustors: annular, with dump diffuser and air-blast fuel atomisers
  • Turbine: 1 LP stage and 1 HP stage

Performance

  • Thrust:
    • Military thrust (throttled):11,687 lbf (52.0 kN)
    • Full afterburner:18,210 lbf (81.0 kN) [Goal: 20,200 lbf (90.0 kN)]
  • Specific fuel consumption:
    • Military thrust: 0.78 lb/(lbf•h) (79.52 kg/(kN·h))
    • Full afterburner: 2.03 lb/(lbf•h) (207.00 kg/(kN·h))
  • Thrust-to-weight ratio: 7.8 (76.0 N/kg)

[edit] Engine cycle

  • Airflow: 172 lb/s (78.0 kg/s)
  • Bypass ratio: 0.16:1 (i.e., "leaky" turbojet)
  • Overall pressure ratio: 21.5:1 [Goal: 27:1]
  • LP compressor pressure ratio: 3.4:1 [Goal: 4:1]
  • HP compressor pressure ratio: 6.4:1
  • Turbine entry temperature: 2,218-2,601 °F (1,214-1,427 °C; 1,487-1,700 K) [Goal: 3,357 °F (1,847 °C; 2,120 K)]

[edit] References

  1. ^ Mama, Hormuz (Nov. 1998). LCA Update. Flight International via Bharat-Rakshak.com.
  2. ^ a b Gunston, Bill (Ed.) (June 15, 2006). "GTRE Kaveri" in Jane’s Aero-Engines, Issue 14. Coulsdon, Surrey, UK: Jane's Information Group Limited. ISBN 0710614055.
  3. ^ Reddy, C. Manmohan (Sep. 16, 2002). LCA economics. The Hindu.
  4. ^ Iype, George (March 2000). 'The LCA won't take off in the near future'. Rediff.com.
  5. ^ Reddy, C. Manmohan (Aug. 9, 2001). Saving the light combat aircraft. The Hindu.
  6. ^ Bedi, Rahul (Dec. 17-30, 2005). Weighed down by history. Frontline.
  7. ^ Anon. (May 30, 2002). Snecma Aerospace India: a new stage in cross-border collaboration. SAFRAN Group website Le Webmag. Retrieved from "Military Aviation and Defense" section Sep. 14, 2006.
  8. ^ Since India does not possess suitable aircraft, the high-altitude testing of the Kaveri is contracted to Russia, which uses a Tu-16 bomber for the purpose. Another Kaveri engine was delivered to Russia for further flight testing from June to September 2006, but on an Il-76 testbed instead of a Tu-16.
  9. ^ Jackson, Paul; Munson, Kenneth; & Peacock, Lindsay (Eds.) (2005). "ADA Tejas" in Jane's All The World's Aircraft 2005-06. Coulsdon, Surrey, UK: Jane's Information Group Limited. p. 195. ISBN 0710626843.
  10. ^ Pandit, Rajat (July 16, 2006). IAF may not get to fly LCA before 2010. The Times of India.

[edit] See also

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