exp 1 - hot water rocket (full report)

8/10/2019 EXP 1 - Hot Water Rocket (Full Report)

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KULLIYAH OF ENGINEERING

INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA

AEROSPACE ENGINEERING LAB IV

MEC 4760

SEMESTER 1, 2013/2014

HOT ATER ROCKET!

NAME AN" MATRIC NO#

MOHAMA" BASHIR BIN MOH" HAFI"$

1014407

LECTURER#

"R% RAE" ISMAIL KAFAFY


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ABSTRACT

Basically, this experiment is to study the performance of hot water rocket by evaluating its

temperature, exit velocity, mass flow rate, thrust and specific impulse. It is being done by

heating of the water to form steam that exits through the nozzle after activating the

solenoid valve to produce thrust. Throughout the experiment, the nozzle exit temperature,

nozzle inlet temperature and thrust is recorded by a relay connected to the computer. This

is essential in order to prove the theory behind the experiment stand correct. However, due

to its relatively simple and basic construction of the rocket, there may be have few

circumstances that can occur which will or may interrupt the result, causing errors to occur.

This set-up although simple is an effective way to achieve the experiment objectives.

OBJECTIVE

To study the performance of hot water rocket by evaluating its temperature, exit

velocity, mass flow rate, thrust and specific impulse.

To study the performance of simple hot water rocket.

INTRODUCTION

Hot Water Rocket (HWR) is a chemical and thermal rocket that uses water as a

propellant that is contained in a pressure vessel at a high temperature. It is being done this

way such that its saturated vapor pressure is significantly greater than ambient pressure.

HWR is categorized as to be part of a non-breathing engine. The water is allowed to

escape as steam through a rocket nozzle, by activating the solenoid valve through the

computer, to produce thrust. As the hot water goes through the nozzle and the pressure

reduces, the water flashes to steam pressing on the nozzle, and leaving at high speed. By


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the recoil the rocket accelerates in the opposite direction to the steam. The nozzle of hot

water rockets must be able to withstand high pressure, high temperatures and the

particularly corrosive nature of hot water.

For this experiment, we will undergo the process of a simple HWR to understand

the principle mechanism of the process. Specifically, the water is heated up to (120 C).

Figure 1: Hot Water Vapor release from Tank

Experiment Setup and Initial Condition Information

Specifications Values

Dt=0.02m Dt=0.018m Dt=0.010m

Diameter inlet, Di(m) 0.025 0.0254 0.0254

Area inlet, Ai(m2) 5.067 x 10

-45.067 x 10

-45.067 x 10

-4

Throat diameter, Dt(m) 0.020 0.018 0.010

Throat area, At(m2) 3.142 x 10

-42.54 x 10

-47.85 x 10

-5

Exit diameter, De(m) 0.0500 0.0256 0.0142

Exit area, Ae(m2) 2.00 x 10

-35.14 x 10

-41.59 x 10

-4

Nozzle area expansion ratio 6.371 2.02 2.02

Nozzle contraction ratio 1.613 1.991 6.452

Table 1.1: the dimensions of the nozzle inlet throat and exit


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PROPERTIES VALUES

Diameter of Tank, D (m) 0.2

Length of Tank, L (m) 1

Slenderness Ratio, L/D 5Volume of Tank, V (m

3) 0.00314

Maximum Mass of Water (L) 31.416

Table 1.2: Tank dimensions and specification

Initial tank temperature, Ti= 298.15K

Initial tank pressure, Pi= 1002.69 kPa

Initial mass of water, mi= 22378 kg

Gas constant, R = 461.5 J/kgK

K = Cp/Cv= 1.327


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Figure 2: Circuit setup for hot water rocket


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Figure 3: Hot Water Tank Figure 4: Data Acquisition


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Figure 5: Spring Balance Figure 6: Solenoid Valve

Figure 7: Pressure and Temperature Sensor


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PROCEDURE

1. We fill the tank with 32 litres of water.

2. Once filled the tank with the water, we heat the tank using heater to a temperature

approximately 120 C.

3. Then, we checked all the sensors functionality and calibrate the spring balance that

is used to measure thrust to zero values.

4. Once prepared, we activate the solenoid valve to release the steam.

5. The nozzle inlet, exit and tank temperatures are recorded into the computer and the

thrust is video recorded throughout the steam released.

RESULTS

Time (s) Mass (kg) Force (N) Tank Temperature

1 0.10 94.3766

2 1.10 94.3958

3 1.38 94.3821

4 1.36 94.3672

5 1.16 94.3711

6 1.16 94.3608

7 1.16 94.3688

8 1.16 94.3751

9 1.16 94.3553

10 1.16 94.3453

11 1.16 94.3443

12 1.16 94.3295

13 1.16 94.3114

14 1.16 94.3134

15 1.16 94.3300

16 1.16 94.3211

17 0.82 94.3384

18 0.44 94.3323

19 0.44 94.3257

20 0.44 94.321321 0.20 94.3184

22 0.15 94.3044


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Time (s) Mass (kg) Force (N) Tank Temperature

23 0.06 94.3012

24 0.04 94.2922

Table 1: Tabulated Result


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Figure 10: nozzle temperature and tank temperature


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DISCUSSIONS

From going through the experiment and result obtained, we are unable to

determined the performance of the hot water rocket. This is due to that the nozzle exitvelocity cannot be calculated as the exit temperature of the nozzle was not properly

recorded. According to the result obtained in Figure 10, we could observe that the exit

temperature starts with zero and decreases over time.

Theoretically, the exit temperature at the nozzle should have an initial value to be

more than zero, roughly at room temperature and due to the nature of the water vapor

being at high temperature released through the nozzle, the exit nozzle temperature should

gradually increase over time. This explained since enthalpy is constant during the flow, thetemperature will increase as the velocity decreasing. Therefore, the result obtained is in

fact, irrelevant.

The problem is probably due to the sensors at the nozzle not being properly

installed or maybe unknown problem occurred to the sensor. The Figure 11 below shows

us the data obtained from same experiment done in the past before us:

Figure 11: nozzle temperature vs time from previous experiment data

The graph clearly shows that the temperature keeps on increasing over time. Thus, the

data that we get from this experiment is not valid for further calculations of exit velocity,

thrust and the specific impulse. Below are the formulas to calculate the mentionedparameters:


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cp(T1 T2) = 1/2(v22 v12)

Assuming that we determined the flow rate 1st, the calculations are as follow:

=

However, the temperature in the tank is in constant after the vapor is released. We could

observe from Figure 8 that the maximum thrust is about 14N. From the calculation above,

the specific impulseis quite low. This value is invalid as the Figure 9 shows the rocket

sustain a constant thrust about 12s.

CONCLUSIONS

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exp 1 - hot water rocket (full report)

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