SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Niklas Wingborg FOI, Energetic materials Chemical Rockets Performance and propellants

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Principle of rocket engines Combustion chamber Nozzle Throat Exit

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Principle of rocket engines De Laval nozzle M 1 T c T t <T c T e <T t

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Gustav de Laval, AB Separator → Alfa Laval 1893 AB de Lavals Ångturbin → Stal-Laval AB → ALSTOM Sverige AB

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Rocket propellant classification Propellant = fuel + oxidizer Liquid propellants – Bipropellant (storable, non-storable, hypergol) – Monopropellant Solid propellants Fuel + oxidizer  gas + energy

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Propulsion systems in the Ariane 5 Cryogenic main core stage Vulcain engine Upper stage with storable propellants and Aestus engine Solid propellant booster

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Propellant performnace Propellant content: up to 90% Not unusual with 50% The performance of the propellant very important Propellant figure of merit: Specific impulse, I sp I sp unit: Ns/kg, m/s or s

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Specific impulse, I sp Optimum mixture oxidizer/fuel  high T c High heat of formation, ΔH f  high T c High hydrogen content  low M CO 2 44 g/mol CO28 g/mol N 2 28 g/mol H 2 O18 g/mol H 2 2 g/mol

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Calculation of specific impulse Nozzle/chamber – Pressure in combustion chamber, p c – Nozzle expansion – Pressure ratio: p c /p e – Area ratio: A e /A t – Chemical equilibrium or frozen equilibrium Propellant – Chemical composition of fuel and oxidizer – Heat of formation of fuel and oxidizer – Mixing ratio fuel/oxidizer

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Thermochemical computation Computer programs for calculation of thermochemical equilibrium and I sp NASA CEA (chemical equilibrium with applications) – NASA Reference Publication 1311 (June 1996) Equation of state: ideal Chemical equilibrium  minimizing ΔG = ΔH-TΔS CEA can be obtained for free – –

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Liquid rocket propellants

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Common liquid rocket propellants Oxidizers – Liquid oxygen, O 2 – Dinitrogen tetroxide, N 2 O 4 – Nitric acid, HNO 3 – Hydrogen Peroxide, H 2 O 2 Fuels – Liquid hydrogen, H 2 – Hydrazine, N 2 H 4 – Monomethylhydrazine – Methane – Unsymetrical dimethylhydrazine – Kerosene – Ethanol

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Liquid oxygen (LOX), O 2 Non storable oxidizer Nontoxic Mp= -219 o C, Bp = -183 o C Used in combination with H 2, kerosene, ethanol Density = 1.14 g/cm 3

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Dinitrogen tetroxide (NTO), N 2 O 4 Widely used storable oxidizer Different percentages (1-3%) of nitric oxide, NO, added as stress corrosion inhibitor (MON-1 and MON-3) MON-1 and MON-3 are used more often than pure NTO Bp= 21°C, Mp=-11°C, dens=1.43 g/cm 3

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Dinitrogen tetroxide (NTO), N 2 O 4 Safety concerns Concern about reactivity of MON with titanium alloys, ignition by friction on freshly formed surfaces (e.g., pyrovalves). History of accidents Toxicity of vapor clouds in case of launch mishaps State governments impose restrictions on transportation of NTO/MON Space agencies have considered manufacturing NTO (and other toxic fuels) at the launch site to alleviate transportation restrictions

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Liquid hydrogen, H 2 Non storable cryogenic fuel, Mp= -259 o C, Bp = -253 o C Used in combination with LOX Density = 0.07 g/cm 3  bulky fuel tank Material problems  brittle at low temperature Air / H 2  explosive

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Hydrazine, N 2 H 4 Can be used as a bipropellant fuel and as a monopropellant Thermally unstable and cannot be used as a regenerative coolant in bipropellant engines As a fuel, it is hypergolic with many oxidizers Positive enthalpy of formation ( kJ/mol = kcal/mol, liquid at 298 K) Bp= 114°C, Mp=+2°C, dens= 1.00 g/cm3

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Hydrazine, N 2 H 4 Hydrazine toxicity concerns Acute toxicity: short-term exposure Chronic toxicity: long-term exposure Volatile Carcinogen

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Monomethylhydrazine (MMH), H 3 C-NH-NH 2 Frequently used storable, hypergolic bipropellant fuel for satellites and upper stages Can be used as a regenerative coolant in bipropellant engines Low freezing point (-52°C) Density = 0.87 Concern about toxicity of vapors (more volatile than hydrazine itself), Bp= +88°C

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 AMSAT P3-D Launch Campaign Kourou N 2 O 4 filling operationMMH filling operation

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Aestus: Ariane 5 upper stage engine Fuel: MMH Oxidizer: N 2 O 4 MMH regenerative cooling Multiple re-ignition capability Thrust: 3 tons Engine mass: 120 kg Length: 2183 mm

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Chamber LcLc Rocket engine design Injector AeAe AtAt

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Injector face Mass flow and mixing  diameter of chamber

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Characteristic velocity, c* Depends on the properties of the propellant Unit: m/s (but it is not a velocity) Independent of pressure (as long the reactions don't change) CEA  c* c*-efficency; ratio between calc. and measured c*

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 UDMH / HNO 3 Characteristic velocity, c*

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Propellant Thrust, pressure and A e /A t CEA  Isp, c* Massflow c* and massflow  A t  A e Injector and massflow  A c Propellant  L c Rocket engine design: summary

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Solid rocket motors

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Solid rocket motors Case with propellant Nozzle Igniter

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Solid propellants Solid mixture of oxidizer and fuel Oxidizer: Ammonium perchlorate (AP), NH 4 ClO 4 Rubber binder matrix: HTPB Fuel: Aluminium powder Burns on the surface Burn time determined by the smallest dimension

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Solid propellant geometry The case is protected by the propellant Shape of combustion channel  pre-programmed pressure and thrust profile

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 VEGA

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Combustion of solid propellants Piece of solid propellant: 10x20x50 mm

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Combustion of solid propellants Small pices of propellants

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Combustion of solid propellants Small pieces burn fast The combustion proceeds perpendicular to the surface Gas generation proportional to burning surface and burning rate, r

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 r measured at different pressures a and n calculated In this case at atmospheric pressure Combustion of solid propellants

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 n must be < 1, preferably 0.5 or lower Combustion of solid propellants

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 r is altered by the initial temperature. A warm propellant burn faster Combustion of solid propellants time pressure T1T1 T2T2 T 2 > T 1

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Solid propellant mechanical properties Cracks in the propellant  > A b  > p c Might lead to failure Good mechanical properties is important Must be elastic Tg < minimum service temperature Good bonding to case important Debonding  > A b  > p c

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Manufacturing composite solid propellants Liquid rubber (HTPB), AP and Al are mixed under vacuum When properly mixed a curing agent is added Continued mixing Cast in mould to obtain desired shape Cured at elevated temperatures Mould = rocket motor Machining Final charge X-rayed to detect cracks, voids etc

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Not possible to obtain maximum theoretical Isp Isp limited by viscosity AP particle size: bimodal or trimodal Manufacturing composite solid propellants % AP Isp (Ns/kg) ~80%

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Composite solid propellants Large amount of smoke is formed AP  HCL  hydrochloric acid Shuttle  ~600 tons conc. hydrochloric acid Ariane-5  ~300 tons conc. hydrochloric acid

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Current trends

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Current trends Green solid propellants to replace AP (ADN, AN, HNF) Green cryogenic solid propellants Green oxidizers (N 2 O, H 2 O 2 ) Hypergolic rocket fuels to replace hydrazine and MMH Green monopropellants to replace hydrazine Exotic molecules, HEDM (N 4, N 8 )

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Minimum smoke propellants

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Why is smoke a concern? NC-baseratAP/Al/HTPB

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Ammonium dinitramide, ADN NH 4 ·N(NO 2 ) 2 Solid white salt Intended for solid propellants No chlorine content Minimum smoke High performance Very soluble in water (80% at RT) Synthesis developed at FOI Produced on license by EURENCO Bofors in Sweden

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 ADN-based solid propellants

SWEDISH DEFENCE RESEARCH AGENCY Niklas Wingborg 2007 Solid propellant testing at FOI Testing of missiles for the Swedish defense