SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  A10-034 (Army)
Title:  Unmanned Aerial Vehicle (UAV) Engine Innovative and Durable Sealing Techniques for Increased Power and Efficiency
Research & Technical Areas:  Air Platform

Acquisition Program:  PEO Aviation
 The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.
  Objective:  Develop and/or demonstrate durable, innovative engine combustion area/hot section sealing techniques that will overcome sealing losses associated with loss of power and efficiency relative to any variety of Unmanned Aerial Vehicle (UAV) heavy fuel engines in the 30 to 150 horsepower class to include but not be limited to turbine, rotary, reciprocating, and non-standard (experimental and non-production) types.
  Description:  It is well known that loss of power and efficiency in internal combustion engines can be a direct result of combustion area (and associated surrounding areas in turbine engines) losses. By minimizing these losses, power and efficiency can be greatly improved. This effort seeks to establish implementation of novel sealing methods/materials to minimize these losses for a candidate engine (30 to 150 horsepower class heavy fuel engine selected by offerer) and derived estimates of improvements to power and efficiency. Dependent upon the engine/engine cycle selected, it is anticipated that this sealing technology would be applicable to combustion pressures in the 8:1 up to 30:1 compression ratio (up to 6:1 pressure ratio for turbine engines) and up to 2500 degree farenheit combustion temperatures. Proposed sealing techniques must also be durable, long life designs which retain good sealing throughout the life of the engine. Some examples of these losses are as follows: Reciprocating Engines: Piston ring blowby, piston ring gap losses, valve/valve seat interface leakage. Ring sealing continues to be an area of ever changing technology. Frictional losses both by the pistons and rings as well as crankcase pressure build-up are known power and efficiency robbers. Rotary Engines: Apex seal leakage and failure, case leakage. Rotary engines Achilles heel are the apex seals. Wear at higher horsepower to weight ratios continues to be a problem and detract from the reliability and longevity of the engines especially in heavy fuel variants required by the military. Turbine Engines: For small turbine engines, hot section sealing requirements involve improved sealing of the turbine blades with advanced shroud designs (minimize blade-to-shroud clearance while retaining durability) and durable sealing techniques to improve air to oil sealing of hot bearing sumps in order to minimize use of secondary air flow (which produces a loss to the cycle) for sump pressurization. Experimental and Non-Standard: Apex seals, sealing vanes. There are numerous experimental concept engines in existence that are either variants on the pistonless rotary concept or are totally in a design class all by themselves. Invariably though, they all must compress an air/fuel mixture in a sealed or momentarily sealing combustion area. Any pressure losses in this area due to insufficient sealing adds to efficiency and power losses.

  PHASE I: Offerer will investigate methods and materials required for improved combustion area/hot section sealing for a selected engine. Implementation of said concept(s) should be well thought out. Laboratory testing of coupon samples or small scale application is encouraged. Based on analysis and testing, a quantifiable measure of improvement to efficiency and power shall be presented.
  PHASE II: Offerer will apply the methods/materials developed in Phase I to a full scale selected engine. Rig testing and data acquisition will be conducted to determine the actual benefits derived from the improved sealing. Offerer will demonstrate the durability/life capability, validity and versatility of the sealing concept/technique and its ability to be utilized on a large scale production basis.

  PHASE III: Offerer will make any final adjustments to the product and look towards mass producing, on a small scale basis, the product and applications of the product to a small engine fleet for long term field evaluation. This will serve to finalize the products final form as well as to validate the life and realized benefits of the product.

  References:   1. Car Craft Magazine-Piston and Ring Technology-by Marlon Davis and various manufacturers ( 2. Advances in Piston Ring technology-by Larry Carley-June 1, 2006.( 3. Experimental and Analytical Study of Ceramic Coated Tip Shroud Seals for Small Turbine Engines-Jan 1985-USAAVSCOM TR 84-C-19 and NASA TM 86881 4. The Development of a Stratified Charge Rotary Engine Apex Seal Material, February 1991,by G S Revankar-Deere and Co. Document No. 910627 5. The Impact of Oil and Sealing Airflow, Chamber Pressure, Rotor Speed, and Axial Load on the Power Consumption in an Aeroengine Bearing Chamber, Journal of engineering for Gas Turbines and Power-January 2005, Issue 1, 182, By Michael Flouros

Keywords:  Combustion area sealing,hot section sealing,apex seals,vane seals,piston and ring technology

Questions and Answers:
Q: The RFP specifically asks for new material seals to improve engine efficiency for UAVs. Without any such new material, would the Army be interested in a UAV propulsion system with an engine that burns heavy fuel and produces about 1 hp per lb. with BSFC of less than 0.45?
A: Since the intent of the subject SBIR topic is to improve sealing on a candidate engine (offeror's choice), and not on development or integration of a complete engine propulsion system (as you have correctly surmised), it doesn't appear as if your offer is a good fit for this effort.

However, the Unmanned Aerial Vehicle (UAV) Program Managers Office at AMRDEC in Huntsville, Alabama is in the UAV propulsion system business and they may provide a better venue to explore the attributes of your product.

Thank you for your interest in this area.
Q: We would like to propose a material approach to the RFP. In Phase II, would the Army provide the test rig for performance and life testing of the seals in a full scale engine?
A: Thank you for your interest in the subject SBIR topic.

Because the nature of the SBIR topic allows the offeror to choose the type of engine the sealing technology will be applicable to, we naturally cannot anticipate what the engine selection would be and therefore cannot provide the test rigs for the wide variety of engines that could be selected.

Rig testing arrangements will have to be made by the successful offeror.

Q: For the rotary UAV engines & Apex Seals, which material is currently being used?
A: Over the years different seal designs and materials have been used and it varies engine to engine.

Q: Would an investigation of piston seals applicable to a low-heat-rejection compression-ignition piston engine of novel construction qualify inder this solicitation?
An engine requiring such seals was investigated for NASA HALE UAV application fifteen years ago. A theory and design approach was developed. Applicable Materials and structures were defined. An engine test bed and coupon wear machine was constructed and tested. Would a proposal to rehab this work be acceptable. Full documantation is available.
A: The focus of the proposed effort is to improve and "push" the combustion area sealing technology for candidate (user selected) engines already developed or as a minimum, having been operated long enough to be able to demonstrate an improvement in efficiency, power, and reduction in emissions through before and after comparisons of operational data.
While we do not specify or have in mind one particular engine(s), we do see this effort as an opportunity to push engine sealing technology, not develop or showcase a new engine or engine design.

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