Study and Development of Throttleable Hybrid Rocket Motors

Transcription

1 Study and Development of Throttleable Hybrid Rocket Motors Alessandro Ruffin University of Padova Centro di Ateneo degli Studi e Attività Spaziali Giuseppe Colombo September 22 nd 2017 Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

2 Throttleable Hybrid Rocket Motors For a fixed nozzle throat, throttleability is achieved by controlling the oxidizer flow Flow control valve (FCV) Advantages Increase trajectory efficency Peculiar mission profiles requiring deep throttling Nammo test, Spartan Project Applications Launchers ADV Flying test beds Requires to control a single feeding line Disadvantages Increase system complexity o/f shifting Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

3 C Penalties Circular port Port fuel consumpion Marxman power law D port 2n 1 o/f = ṁ1 n ox 4 n π 1 n a ρ f L Characteristic velocity [m/s] HTP N 2 O LOX n = 0.5 no D port sensitivity n = 1 no ṁ ox sensitivity n [ ] o/f [] 90%HTP N 2 O LOX Maximum c [m/s] c Sensitivity [m/s] c Penalty TR=5 (balanced) 95.3% 95.9% 96.2% c Penalty TR=5 (fuel rich) 88.0% 84.5% 82.7% c Penalty TR=10 (balanced) 91.6% 92.8% 93.2% c Penalty TR=10 (fuel rich) 78.3% 78.5% 75.4% Arbitrary throttling o/f shift Performance reduction Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

4 FCV selection Techniques: Pure dissipative valve Variable area injection Parallel feeding lines Variable area cavitating venturi Peculiarities variable area flow control if p up > [ ] p down tank - combustion chamber uncoupling For a CV: Pressure [bar] cat postcc tank ox ṁ ox = C d A th 2 ρox (p p sat ) Time [s] Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

5 This year: Flow control valve design concluded Integration and testing Flow control valve characterization Static hybrid rocket motor fire tests Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

6 FCV: Design VALVE ACTUATION FCV Step DC Motor Encoder Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

7 FCV: Design Features Conical pintle/spike Manually moved pintle Pressure tap for feedback Minimum mass flow range Maximum mass flow range Maximum operating pressure Venturi throat diameter Upstream throat radius Venturi divergence angle Pintle apex angle Maximum pintle stroke Useful pintle stroke Alessandro Ruffin 30 [g /s] 300 [g /s] 80 [bar ] 2.2 [mm] 3.3 [mm] 10 [deg ] 10 [deg ] 11 [mm] 7 [mm] Throttleable Hybrid Rocket Motors September 22nd / 14

8 FCV characterization: Set-up Ptank Pup Pdown x PR1 PR2 VACV V05 Vc Vtes t Vdump To collector Vpurg e HTP tank N2 tank Vtank To collector Low pressure N2 Features HTP tank (piston separator) Flow control valve Catalytic bed (not shown) Test motor (not shown) Purging line Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd / 14

9 FCV characterization: Results H 2 O 91 % HTP bar 45 bar 60 bar bar 45 bar 60 bar Measured mass flow [g/s] Measured mass flow [g/s] Pintle stroke [mm] Pintle stroke [mm] Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

10 FCV characterization: Results H 2 O 91 % HTP Discharge coefficient [] bar 45 bar 60 bar fit Discharge coefficient [] bar 45 bar 60 bar fit Pintle stroke [mm] Pintle stroke [mm] C D,H2 0 = x x /x, R 2 = 0.93 C D,HTP = x x /x, R 2 = 0.86 Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

11 Test Motor: Fire test campaign A test campaign was conducted to characterize the test motor behavior with different mass flows. Tests were conducted in the fuel rich region. 30 post catalytic combustion chamber Pressure [bar] Test # ṁ HTP t b p cc [g/s] [s] [bar] Time [s] Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

12 Test Motor: Fire test campaign A test campaign was conducted to characterize the test motor behavior with different mass flows. Tests were conducted in the fuel rich region Combustion chamber pressure [bar] Test # ṁ HTP t b p cc [g/s] [s] [bar] Oxidizer mass flow [g/s] Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

13 Conclusion and Future work A variable area cavitating venturi to be used as flow control valve in hybrid rocket motors was developed and characterized Our test motor was tested with four different oxidizer mass flows reaching a 1:5 throttling ratio Automatically control the pintle stroke implementing a DC motor Characterize the dynamic behavior of flow control valve and test motor Throttling tests Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14

14 Conclusion Thank you! Any question? Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22 nd / 14